National Electrical Code Forum. Your Questions Answered

National Electrical Code Forum Your Questions Answered

Meet Your Distinguished Experts Moderator: Lloyd Osborn- Cheyenne, Wyoming Tom Lichtenstein Republican Organizer-Chicago, IL Tim McClintock NFPA Regional Representative-Wooster, OH Marcus Sam Sampson Western Section 1 st Vice President, CMP 15-St Paul, MN Vince Saporita Cooper/Bussmann, CMP 10 & 11, NEC Correlating Committee-St Louis, MO Phil Simmons Simmons Electrical Service, CMP 5-East Olympia, WA Christine Porter Intertek Field Evaluator, CMP 5-Seatle, WA

Recessed Fluorescent Troffer Securement 1. Do the factory wings that many fluorescent troffers have designed to fold out over the grid meet the requirements for securely fastened to the framing? Reference: NEC 410.16(B) Answer: No, 410.36(B) Requires as bolts, screws, or rivets or Listed clips identified for use with the type of ceiling framing member and luminaire. See FLUORESCENT RECESSED LUMINAIRES (IEVV) located on page 174 in the 2012 UL White Book. States Recessed luminaires intended for use in suspended ceilings and provided with integral clips are marked for use with particular grid systems. Separate Clips Listed under Luminaire Fittings (IFFX) on page 187 in UL White Book

Emergency Lights: Unit Equipment 2) Is it a code violation to have general purpose receptacles on the same lighting circuit that has required battery backed up emergency lights Reference: NEC 700.12 Answer: No 700.12 (in part): Last paragraph: 700.12 General Requirements: Unit equipment in accordance with 700.12(F) shall satisfy the applicable requirements of this article. 700.12(F): Flexible cord-and-plug connection shall be permitted, provided that the cord does not exceed 900 mm (3 ft) in length. 700.12(F): The branch circuit feeding the unit equipment shall be the same branch circuit as that serving the normal lighting in the area and connected ahead of any local switches.

3. Is it allowed to use the grounding grid of the pools patio as the grounding electrode system for a separate structure s pool equipment? Answer: No Reference: 680.26(B)(2) Equipotential Bonding and 250.52 Grounding Electrodes

680.26 Equipotential Bonding (A) Performance. The equipotential bonding required by this section shall be installed to reduce voltage gradients in the pool area.

680.26 Equipotential Bonding (B) Bonded Parts. The parts specified in 680.26(B)(1) through (B)(7) shall be bonded together using solid copper conductors, insulated covered, or bare, not smaller than 8 AWG or with rigid metal conduit of brass or other identified corrosion-resistant metal. (2) Perimeter Surfaces. The perimeter surface shall extend for 1 m (3 ft) horizontally beyond the inside walls of the pool and shall include unpaved surfaces, as well as poured concrete surfaces and other types of paving.

680.26 Equipotential Bonding

250.52(A) Electrodes Permitted for Grounding (1) Metal Underground Water Pipe in direct contact with the earth for 3.0 m (10 ft) (2) Metal Frame of the Building or Structure in direct contact with the earth for 3.0 m (10 ft) or more (3) Concrete-Encased Electrode at least 6.0 m (20 ft) encased by at least 50 mm (2 in.) of concrete (4) Ground Ring at least 6.0 m (20 ft) of bare copper conductor at a depth not less than 750 mm (30 in.) (5) Rod and Pipe Electrodes not be less than 2.44 m (8 ft) in length (6) Other Listed Electrodes Man-made (7) Plate Electrodes not less than 0.186 m2 (2 ft2) of surface to exterior soil (8) Pool perimeter equipotential bonding grid

3. Is it allowed to use the grounding grid of the pools patio as the grounding electrode system for a separate structure s pool equipment? Answer: No

Generator/ Loading 4. A 3-phase 120/208-volt generator nameplate shows the rating to be 275KW and 285KVA. The load calculation by the engineer shows the load on the generator to be 790-amperes. Is this acceptable? Reference: Article 445 Generators, 110.3(B) Answer: There is nothing in Article 445 that limits a generator to 80% of its rating. Therefor it can be utilized at 100% of its rating. 285,000/(1.732X208) = 791.1 amperes = FLA of generator. The load on the generator is 790 amperes. Therefore, this is acceptable.

Grounding & Bonding, More than One Bldg 5. 2011 NEC 250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s) requires that an EGC be installed with the feeder conductors and bonded to the subpanel in the outbuilding. In addition, a GEC is to be installed to all available electrodes at the separate structure. If there are no available electrodes and a ground rod is driven and an appropriately sized GEC installed, is it required that this ground rod be supplemented as required in 250.53(A)(2) or can the one ground be considered supplemented by the main electrode system using the EGC to bond them together Reference: NEC 250.32; 250.53(A)(2) Answer: Treat each building or structure as an Island so far as grounding electrode systems are concerned. Two ground rods are required at the building or structure supplied by a feeder unless a single rod meets the 25 Ohm rule in 250.53(A)(2) Exception.

PVC expansion fittings 6) A 200 ampere, 277/480 volt feeder is installed in 50 feet of 2½", Schedule 80, PVC Rigid Nonmetallic Conduit on the south side of a steel building. During the winter months, the outdoor temperature differs by as much as 50 degrees ( F). How much will the conduit expand in length with this change of temperature? And would an expansion type of fitting be required? Reference: NEC 352.44 and Table 352.44 Answer: 1.015 inches, and YES fitting is required A fitting is to be used whenever the length change is expected to be equal to or greater than 6mm (1/4 ) Straight runs between anchored points No difference between Schedule 40 & Schedule 80 conduits

Table 352.44 (in part) 6) continued

Compact Fluorescent Lamps 7. Is it permissible to install compact fluorescent lamps in existing 6-inch recessed luminaires? Reference: 110.3(B) Answer: Yes, see Self Ballasted Lamps and Lamp Adapters (OOLR) on page 278 in the 2012 UL White Book. The OOLR Guide Information states These products have been investigated for use in the smaller of a 6- or 8-in. diameter, totally enclosed, recessed luminaire, if they will physically fit, unless marked not for use in a totally-enclosed luminaire.

GFCI Requirements for Basements 8) A basement is finished except for the concrete floor which remains original. Is GFCI protection required for all 120volt outlets in this area?

GFCI Requirements for Basements 8) A basement is finished except for the concrete floor which remains original. Is GFCI protection required for all 120volt outlets in this area? Reference: NEC 210.8(A)(5) & 90.4 Answer: 210.8 requires ground-fault circuit-interruption for personnel shall be provided as required in 210.8(A) through (C). 210.8(A)(5) Unfinished basements for purposes of this section, unfinished basements are defined as portions or areas of the basement not intended as habitable rooms and limited to storage areas, work areas, and the like. GFCI protection would be an AHJ call for the receptacle outlets located in this basement. The term unfinished first appeared in the 1990 NEC. CMP 2 formulated a panel statement in Comment 2-647 of the 1989 TCR that stated Determination of whether a basement is finished or unfinished is subject to the authority having jurisdiction.

9. A hot tub is surrounded by a wooden fence with metal poles that are within 5 of the water s edge. Do all of the metal poles within the 5 need to be to be bonded to the equipotential bonding grid? Reference: 680.26(B)(7) Answer: Yes

680.26 Equipotential Bonding (A) Performance. The equipotential bonding required by this section shall be installed to reduce voltage gradients in the pool area.

680.26 Equipotential Bonding (B)(7) Fixed Metal Parts. All fixed metal parts shall be bonded including, but not limited to, metal-sheathed cables and raceways, metal piping, metal awnings, metal fences, and metal door and window frames.

9. Do all of the metal poles within the 5 need to be to be bonded to the equipotential bonding grid? Answer: Yes

Circuit Breakers/ Handle Ties 10. Can two outside breakers of adjacent four pole, common trip, breakers be utilizes as a common trip breaker, for 240 volt loads, if they are tied with an approved handle tie? Reference: 240.15(B)(1) & (2) Answer: No. 240.15(B)(1) states that Individual single-pole circuit breakers, with identified handle ties, shall be permitted as the protection for each ungrounded conductor of multi-wire branch circuits that serve only single-phase line-to-neutral loads. These are not single pole circuit breakers, therefore, handle ties are not allowed.

Bonding Jumper Required? 11. Is an equipment bonding jumper required between a cable tray and free standing switchgear when uncoated type MC cables drop from the tray to the switchgear? Reference: NEC 392.60(C) Answer: Yes, a bonding jumper is required. It is to be sized in accordance with 250.102. 250.102(C) Supply-Side Bonding Jumper applies if there is no overcurrent protection on the supply side. 250.102(D) Equipment Bonding Jumper on Load Side of an Overcurrent Device applies if there is overcurrent protection on the supply side.

T-Grid Mounting of Outlet Boxes 12) Does the NEC allow a 4 square box for t-grid lighting fixture branch Circuit conductor to be attached to the t-grid if a support bracket made for this purpose Reference: NEC 314.22(D) Answer: Yes - 314.22(D) (in part) (D) Suspended Ceilings. An enclosure mounted to structural or supporting elements of a suspended ceiling shall be not more than 1650 cm3 (100 in.3) in size and shall be securely fastened in place in accordance with either (D)(1) or (D)(2). (1) Framing Members. An enclosure shall be fastened to the framing members by mechanical means such as bolts, screws, or rivets, or by the use of clips or other securing means identified for use with the type of ceiling framing member(s) and enclosure(s) employed.

Lighting Fixtures and Listing 13. Are all lighting fixtures required to be listed and labeled? Reference: NEC 410.6 Answer: Yes, see NEC 410.6 which states All luminaires and lampholders shall be listed. This went into effect in the 2008 NEC. For the 2014 NEC all retrofit kits will also be required to be Listed.

GFCI Requirements for Vending Machines 14) Is it a violation to install a GFCI receptacle for the vending machine behind the vending machine indoors in a hallway of a commercial building? Reference: NEC 210.8 & 422.51 Answer: No it would not be a violation. The change in the 2011 NEC to require GFCIs to be readily accessible only includes those under the purview of 210.8. 2005 NEC section 422.51 added requirements for GFCI protection of cord-andplug-connected vending machines. 2008 NEC was revised to include a description of a vending machine, with a FPN on the applicable product standards. 2011 NEC was revised by was relocating the definition to 422.2 2014 NEC will include a new requirement for accessibility to devices providing GFCI protection where such protection is specified by an Article 422 requirement.

15. Is NM-B cable allowed in any areas of a dwelling unit that has been converted to a dental office? Reference: 517.10(B) Answer: Yes

ICC Building Code SECTION 908 ELECTRICAL 908.1 Special occupancies Where the occupancy of an existing building or part of an existing building is changed to one of the following special occupancies the electrical wiring and equipment of the building or portion thereof that contains the proposed occupancy shall comply with the applicable requirements of the International Code Council Electrical (National Electrical Code )

908.1 Special Occupancies 1. Hazardous locations. 2. Commercial garages, repair, and storage. 3. Aircraft hangars. 4. Gasoline dispensing and service stations. 5. Bulk storage plants. 6. Spray application, dipping, and coating processes. 7. Health care facilities. 8. Places of assembly. 9. Theaters, audience areas of motion picture and television studios, and similar locations. 10. Motion picture and television studios and similar locations

517.2 Definitions Health Care Facilities. Buildings or portions of buildings in which medical, dental, psychiatric, nursing, obstetrical, or surgical care are provided Patient Care Area. Any portion of a health care facility wherein patients are intended to be examined or treated.

517.10 Applicability (A) Part II shall apply to patient care areas of all health care facilities. (B) Not Covered. Part II shall not apply to: (1) Business offices, corridors, waiting rooms, and the like in clinics, medical and dental offices, and outpatient facilities

517.13 Grounding of Receptacles and Fixed Electrical Equipment in Patient Care Areas Wiring in patient care areas shall comply with 517.13(A) and (B)

517.13 Grounding of Receptacles and Fixed Electrical Equipment in Patient Care Areas (A) Wiring Methods. All branch circuits serving patient care areas shall be provided with an effective ground-fault current path by installation in a metal raceway system, or a cable having a metallic armor or sheath assembly. The metal raceway system, or metallic cable armor, or sheath assembly shall itself qualify as an equipment grounding conductor in accordance with 250.118.

517.13 Grounding of Receptacles and Fixed Electrical Equipment in Patient Care Areas (B) Insulated Equipment Grounding Conductor. (1) General. The following shall be directly connected to an insulated copper equipment grounding conductor that is installed with the branch circuit conductors in the wiring methods as provided in 517.13(A). (1) The grounding terminals of all receptacles. (2) Metal boxes and enclosures containing receptacles. (3) All non current-carrying conductive surfaces

15. Is NM-B cable allowed in any areas of a dwelling unit that has been converted to a dental office? Answer: YES

Photovoltaic/ Overcurrent Protection 16. Are the conductors from a photovoltaic array required to have overcurrent protection when they enter a building? What if the modules are AC modules? Reference: 690.9 and 690.11 Answer: Requirements for overcurrent protection are independent of whether or not the conductors enter a building. 690.9 (A) Circuits and Equipment. Photovoltaic source circuit, photovoltaic output circuit, inverter output circuit, and storage battery circuit conductors and equipment shall be protected in accordance with the requirements in Article 240. Overcurrent protection whether for AC or DC has nothing to do with whether or not the conductors enter the building. The question may be confusing AFCI protection, which is not overcurrent protection. Per 690.11, DC AFCI protection is required where photovoltaic systems are installed on or penetrate a building

Size of GEC Related to Voltage Drop 17. A 200-amp circuit is increased from 3/0 copper to 500 kcmil copper to compensate for voltage drop. What size copper equipment grounding conductor would be required for this circuit? Reference: NEC 250.122(B) increased in proportion to the increase of the ungrounded conductors Answer: 500,000 cm = 2.98 (Ratio of increase) 167,800 cm 26,240 cm (6 AWG EGC) X 2.98 = 78,195 cm = 1 AWG EGC

MC cable horizontally run through studs 18) Is it required to maintain 1 ¼ or use a nail plate when running MC horizontally through shallow metal studs? Reference: NEC 330.17 Answer: No 330.17 (in part): 330.17 Through or Parallel to Framing Members. Type MC cable shall be protected in accordance with 300.4(A), (C), and (D) where installed through or parallel to framing members. (A) refers cables & raceways routed through wood framing members (C) refers to NM cables and ENT routed through metal framing members (D) refers to cables and raceways routed parallel to framing members

HVAC RTU Receptacle 19. If a rooftop unit comes with a built in GFCI receptacle on the face of the unit that comes with the old wet location trim cover. Is it within the AHJ s jurisdiction to require an in-use cover and WR type receptacle? Reference: 90.4, 90.7, 300.1(B), 406.9(B)(1), LZFE pg. 239 UL WB Answer: Yes and No. AHJ always has the jurisdiction to accept or deny per 90.4. 406.9(B)(1) requires the WR receptacle and the bubble cover for premise wiring receptacles. However, Listed HVAC equipment, NEC does not apply to the construction of the RTU, this is governed by the safety standard. See 90.7 and 300.1(B). These products are Listed under (LZFE) on page 239 in the 2012 UL White Book, evaluated to the Standard for Safety for Heating and Cooling Equipment, UL 1995. Presently, UL 1995 does not require the a WR receptacle or a bubble cover. Effective October 2014, Listed HVAC units with receptacles will have to be WR have a bubble cover or pass the rain test and the receptacle provided with a separate disconnect. This information can be found in the UL Question Corner of the latest March April IAEI News magazine.

Grounding Requirements for PV Systems 20) Is it legal to use the AC equipment grounding conductor as the grounding electrode conductor for the DC side grounding point in a solar photovoltaic system? Reference: NEC 690.47(C)(3) Answer: 690.47(C) Systems with Alternating-Current and Direct-Current Grounding Requirements. Photovoltaic systems having dc circuits and ac circuits with no direct connection between the dc grounded conductor and ac grounded conductor shall have a dc grounding system. The dc grounding system shall be bonded to the ac grounding system by one of the methods in (1), (2), or (3). (3) Combined Direct-Current Grounding Electrode Conductor and Alternating-Current Equipment Grounding Conductor. An unspliced, or irreversibly spliced, combined grounding conductor shall be run from the marked dc grounding electrode conductor connection point along with the ac circuit conductors to the grounding busbar in the associated ac equipment. This combined grounding conductor shall be the larger of the sizes specified by 250.122 or 250.166 and shall be installed in accordance with 250.64(E). 250.121 new for the 2011 NEC prohibits an equipment grounding conductor from being used as a grounding electrode conductor. However that is a general rule (90.3) modified by 690.47(C)(3).

21. In a 22 pole light, is it required to connect the auxiliary grounding electrode conductor going to the lug in the hand hole to the equipment grounding conductors by means of a wire nut or split bolt? Reference: 250.54 Answer: NO

250.54 Auxiliary Grounding Electrodes One or more grounding electrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.118

250.54 Auxiliary Grounding Electrodes and shall not be required to comply with the electrode bonding requirements of 250.50 or 250.53(C) or the resistance requirements of 250.53(A)(2) Exception

Service Entrance/ Feeder Tap 22. I have installed a 200 ampere, 120/240 volt, single phase, rain-tight, meter/main breaker panel with eight breaker spaces and 200 ampere rated, feed-thru lugs on the exterior of a dwelling unit. I have terminated 2/0 aluminum, SER cable on the feed-thru lugs and ran 20 feet (total wire length) of this cable through a non-insulated basement ceiling and into a 125 ampere main breaker panel located in the basement. The inspector wrote that the feeder cable has to be rated for 200 amperes. I believe that I have installed this feeder to meet the requirements of the tap rules of Article 240.21(B)(2) and that the installation should be approved. Who is correct? Reference: Table 310.15(B)(16), 310.15(B)(7), Table 310.15(B)(7), Definition of Tap in 240.2, 240.21(B)(2) Answer: The inspector is always right. The ampacity for 75 degree C 2/0 aluminum is 135 amperes, but Table 310.15(B)(7) would allow 2/0 aluminum to serve a 150 ampere service/feeder if it meets the requirements of 310.15(B)(7). Note that it must serve the entire building load, so there can be no other loads fed from the 200 ampere panel. So, it looks as if the ampacity of the cable is adequate. But, now it needs to be protected. I tried using the 25 foot tap rule, but cannot, because the conductors terminate in a 150 ampere CB which is greater than the ampacity of the conductor, and you can t round up when using the tap rules. In this case, going to a 3/0 would have increased the ampacity to 155 amperes, so termination in a 150 ampere CB would be OK.

Size of GEC to Ground Ring Electrode 23. What is the minimum size copper grounding electrode conductor allowed to connect to a ground ring that is specified to be a 250 kcmil cu and the service is a 400A fed with 4-500 kcmil cu Reference: NEC Table 250.66 and 250.66(C) Answer: 500 kcmil X 4 = 2,000 kcmil Table 250.66 requires a 3/0 AWG copper GEC 250.66(C) does not directly apply as the 250 kcmil Ground Ring is larger than the largest GEC required by Table 250.66,

FPLP installed in wet locations in PVC 24) In a power limited fire alarm system is it a code violation to install FPLP (which is not listed for wet locations) in PVC conduit underground from building 1 to building 2? Reference: NEC Art 100 Definitions, 760.3(D), 760.179(D) Answer: YES - 760.3(D) and 760.179 (in part) 760.3 Other Articles (D) Corrosive, Damp, or Wet Locations. Sections 110.11, 300.6, and 310.10(G), where installed in corrosive, damp, or wet locations.

FPLP installed in wet locations in PVC 24) continued 760.179 Listing & Marking of PLFA Cables and Insulated Continuous Line-Type Fire Detectors. (in part) (D) Type FPLP. Type FPLP power-limited fire alarm plenum cable shall be listed as being suitable for use in ducts, plenums, and other space used for environmental air and shall also be listed as having adequate fire-resistant and low smoke producing characteristics. Underground locations are wet locations Cables in wet locations must be a type listed for wet locations

Maximum Number of Smoke Alarms 25. How does one calculate the maximum number of multiple single station smoke alarms that can be interconnected in a building? Reference: 110.3(B), NFPA 72, (UTGT) Pg. 378 UL WB Answer: You don t calculate the number of smoke alarms that can be interconnected, you look in the installation instructions provided with the Listed detectors and NFPA 72 the National Fire Alarm Code which limits them to 12.

AFCI Requirements for Dwelling Units 26) Is the washer outlet branch circuit in a laundry room required to be AFCI protected? Is the entire laundry room required to be AFCI protected? Reference: NEC 210.12(A) Answer: No 210.12(A) does not include a requirement for laundry rooms. 210.12 (A) Dwelling Units. All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arcfault circuit interrupter, combination-type, installed to provide protection of the branch circuit. 2014 NEC : Revised to expand AFCI protection requirement to kitchens and laundry areas and to specify AFCI protection is required for branch circuits supplying outlets and devices.

27. If an electric water fountain uses a GFCI receptacle for protection, is it required to be readily accessible? Reference: 422.52; 210.8 & Article 100 Answer: YES

ARTICLE 422 Appliances IV. Construction 422.52 Electric Drinking Fountains. Electric drinking fountains shall be protected with ground-fault circuit-interrupter protection. The GFCI protection may be an integral part of the fountain, may be provided at the receptacle for the fountain, or on the branch circuit feeding the fountain.

210.8 Ground-Fault Circuit-Interrupter Protection for Personnel The ground-fault circuit-interrupter shall be installed in a readily accessible location.

100. Definitions Accessible, Readily (Readily Accessible). Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth.

27. If an electric water fountain uses a GFCI receptacle for protection, is it required to be readily accessible? Answer: YES

Fire Pump/ Switch Location 28. If we have a 125HP fire pump that is located in another room from the fire pump control (not within sight), do I need to install another disconnect for the pump if the fire pump controller disconnect is lockable? If I do install a disconnect switch, what is the rating of the switch? Reference: 695.4(B)(1)(a) General. A single disconnecting means and associated overcurrent protective device(s) shall be permitted to be installed between the fire pump power source(s) and one of the following: Answer: Not only is the disconnect not needed, per 695.4(B)(1), it is not allowed. The disconnect at the controller is sized to carry the locked rotor current of all the permitted motors plus the sum of any other fire pump auxiliary loads.

Insulating Restrictions 29. Where the utility company installs 1/0 aluminum service conductors instead of the 4/0 AL that are required per NEC for a 200 amp service is it compliant to install a 8 AWG GEC per 250.66 Reference: NEC Table 250.66 Note 2 Answer: The conductors installed by the utility would be either a service lateral or service drop, neither of which are covered by the NEC. The size of conductors required by the NEC would require a 4 AWG GEC unless the exception of 250.66(A) applies.

Bonding Low Voltage Enclosures 30) Is it required to ground or bond all metal low voltage enclosures throughout a commercial building? Reference: NEC 250.96(A), 250.112(I) Answer No 250.96 Bonding Other Enclosures. (in part) (A) General. Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal non current-carrying parts that are to serve as equipment grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be bonded where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed on them.

Bonding Low Voltage Enclosures 30) Continued 250.112(I) Specific Equipment Fastened in Place (Fixed) or Connected by Permanent Wiring Methods (in part) (I) Remote-Control, Signaling, and Fire Alarm Circuits. Equipment supplied by Class 1 circuits shall be grounded unless operating at less than 50 volts. Equipment supplied by Class 1 powerlimited circuits, by Class 2 and Class 3 remote-control and signaling circuits, and by fire alarm circuits shall be grounded where system grounding is required by Part II or Part VIII of this article. Does the system require grounding? Are there special requirements such as for Haz Loc installations or electric signs, etc.? If so, the answer may change to Yes

Emergency Lights Battery Back-up 31. Do emergency lights with individual battery back-up require a test switch and a charging indicator light? If yes, do they have to be visible?? Reference: FTBR, Pg. 158 UL White Book, UL 924 Answer: Yes and Yes. Listed under Emergency Lighting and power Equipment (FTBR), see pg. 158 in the 2012 UL White Book. The Standard for Safety for Emergency Lighting and Power Equipment UL 924. requires equipment incorporating storage batteries and battery-charging means shall provide audible or illuminated visible indicator(s) detectable to facility occupants without the need to adjust or remove any equipment covers or parts they also need a test switch or provision to connect a test switch (which can be mounted remote from the equipment, for easier access).

GFCI Breaker Requirements 32) The 2-pole 50-amp GFCI breaker for a hot tub is installed in the disconnect 6 feet from the tub. It is a 240-volt 3-wire hot tub. Is a neutral required to be brought to the disconnect for the reference of the GFCI breaker? Or can the factory white neutral reference from the breaker be terminated on the equipment ground bar? Reference: NEC 680.44 & 110.3(B) Answer: 680.44: specifies the outlet(s) that supplies a self-contained spa or hot tub, a packaged spa or hot tub equipment assembly, or a field-assembled spa or hot tub shall be protected by a ground-fault circuit interrupter.

33. Where conduit is required for life safety & critical branch circuits, is it a violation to use factory fixture whip taps for the 6 termination to a 2 x4 emergency light?

517 Part III Essential Electrical System 517.30(B) (2) Emergency Systems. The emergency system shall be limited to circuits essential to life safety and critical patient care. These are designated the life safety branch and the critical branch.

517.30(C)(3) Mechanical Protection of the Emergency System. The wiring of the emergency systems in hospitals shall be mechanically protected. The following wiring methods shall be permitted: (3) Listed flexible metal raceways and listed metal sheathed cable assemblies in any of the following:

a. Where used in listed prefabricated medical headwalls

b. In listed office furnishings

c. Where fished into existing walls or ceilings, not otherwise accessible and not subject to physical damage

d. Where necessary for flexible connection to equipment

33. Where conduit is required for life safety & critical branch circuits, is it a violation to use factory fixture whip taps for the 6 termination to a 2 x4 emergency light? Answer: NO

Sizing Motor Circuits/ Fuse, EGC, and Conductors 34. A 100 hp, 3-phase, 480 volt motor is fed with #2/0 AWG, Type THHN/THWN, copper conductors protected with Type Non-400 ampere fuses and a #6 AWG copper EGC. Are the motor circuit conductors, EGC, and fuses properly sized? Reference: Table 430.52 (and Exception No. 1), 240.6), Table 430.250, 430.22, Table 310.15(B)(16), 250.122, and Table 240.122. Answer: From Table 430.52 a non-time delay fuse can be sized as high as 300% of FLA, which is 124 amperes from Table 430.250. 3 X 124 = 372 amperes. Exception No. 1 allows the next standards size, which 240.6 shows as a 400 ampere fuse, which agrees with the question. However, the fuse in question is only a 250 volt fuse, so it would be a violation of 110.3(B) to use the 250 volt fuse on a 480 system. An NOS 400 fuse would be required for this application. 430.22 requires that the motor circuit conductor have an ampacity of at least 1.25 X 124 = 155 amperes. Table 310.15(B)(16) shows a 2/0, 75 degree C conductor to have an ampacity of 175 amperes. Table 250.122 would indicate that a 3 AWG conductor is adequate for the EGC, so the 6 AWG conductor would also be in violation.

GEC Connection to Ufer GEC 35. Why is a UFER connection required to be accessible? Reference: NEC 250.68(A) Exception Answer: The connection is not required to be accessible due to the nature of the connection inside poured concrete.

Bushing on RMC nipple? 36) I installed a short rigid nipple out the back of a panel to an LB that has a 5 length of EMT to a disconnect switch for an AC unit. It only has #10 copper wires in the conduit and the inspector wants a bushing on the inside of the panel. Is he correct? Reference: NEC 310.4(G) and 344.46 Answer - No unless fitting or raceway does not provide smooth edge 310.4(G) Insulated Fittings. (in part) Where raceways contain 4 AWG or larger insulated circuit conductors, and these conductors enter a cabinet, a box, an enclosure, or a raceway, the conductors shall be protected by an identified fitting providing a smoothly rounded insulating surface, unless the conductors are separated from the fitting or raceway by identified insulating material that is securely fastened in place.

Bushing on RMC nipple? 36) Continued 310.4(G) Exception: Where threaded hubs or bosses that are an integral part of a cabinet, box, enclosure, or raceway provide a smoothly rounded or flared entry for conductors. 344.46 Bushings. Where a conduit enters a box, fitting, or other enclosure, a bushing shall be provided to protect the wires from abrasion unless the box, fitting, or enclosure is designed to provide such protection. If the nipple is listed, it is required by UL 6 to provide the smooth edge, and would meet the requirement in 344.46. If the nipple was manufactured in the field then it would be up to the AHJ to determine if the nipple provides a smoothly rounded edge for the conductors to pass over.

Grounding Lug to Painted Box 37. I have a junction box that is 1/16th of an inch thick that is painted. I drilled and tapped that box for a 10/32 screw for bonding the box. Do I need to remove the paint or will the thread contact be sufficient for making contact between the lug and the box? Reference: 250.12 Answer: Yes, you need to remove the paint. 250.12 states Nonconductive coatings (such as paint, lacquer, and enamel) on equipment to be grounded shall be removed from threads and other contact surfaces to ensure good electrical continuity or be connected by means of fittings designed so as to make such removal unnecessary.

Ground Bushings 38) Are ground bushings listed for a choke on the GEC when installed in a ferrous raceway? Reference: Answer: NEC 250.64(E) & 250.92(B) 250.64(E) Ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made electrically continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor. Bonding methods in compliance with 250.92(B) for installations at service equipment locations and with 250.92(B)(2) through (B)(4) for other than service equipment locations shall apply at each end and to all intervening ferrous raceways, boxes, and enclosures between the cabinets or equipment and the grounding electrode. Grounding bushings are Listed under Grounding and Bonding Equipment, (KDER) These bonding connections are necessary so that the ferrous raceway does not create an inductive choke on the grounding electrode conductor. By virtue of the bonding connection, there is no choke.

39. Is it compliant to run health care facility cable through PVC in the concrete floor as long as it is not slab on grade for dental chair receptacles? Reference 517.13 Answer: Maybe

517.13 (A) Wiring Methods The metal raceway system, or metallic cable armor, or sheath assembly shall itself qualify as an equipment grounding conductor in accordance with 250.118.

300.5(C) Underground Cables Under Buildings Underground cable installed under a building shall be in a raceway. Exception No. 2: Type MC Cable listed for direct burial or concrete encasement shall be permitted under a building without installation in a raceway in accordance with 330.10(A)(5) and in wet locations in accordance with 330.10(A)(11).

330.10 Uses Permitted (A) General Uses. Type MC cable shall be permitted as follows: (1) For services, feeders, and branch circuits. (2) For power, lighting, control, and signal circuits. (3) Indoors or outdoors. (4) Exposed or concealed. (5) To be direct buried where identified for such use. (6) In cable tray where identified for such use. (7) In any raceway. (8) As aerial cable on a messenger.

314.3 Nonmetallic Boxes Nonmetallic boxes shall be permitted only with open wiring on insulators, concealed knob-and-tube wiring, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways. Exception No. 1: Where internal bonding means are provided between all entries, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables

330.40 Boxes and Fittings Courtesy Thomas & Betts Fittings used for connecting Type MC cable to boxes, cabinets, or other equipment shall be listed and identified for such use.

39. Is it compliant to run health care facility cable through PVC in the concrete floor as long as it is not slab on grade for dental chair receptacles? Answer: Maybe, if the MC cable can be properly terminated to a listed box or assembly at or beneath the dental chair

Sizing Motor Circuits/ Use of the Tables 40. When determining the Maximum Rating or Setting of Motor Branch-Circuit Short-Circuit and Ground-Fault Protective Device using Table 430.52, do I use the motor amperages shown in Tables 430.247 through 430-250 for all type of motor applications or the nameplate rating on the motor(s)? and why? Reference: 430.6(1) Table Values. Other than for motors built for low speeds (less than 1200 RPM) or high torque, and for multi-speed motors, the values given in Table 430.247, Table 430,248, Table 430.249, and Table 430.250 shall be used to determine the ampacity of conductors or ampere ratings of switches, branch-circuit short-circuit and ground-fault protection, instead of the actual current rating marked on the motor nameplate. Answer: Use the tables for all but low speed, high torque and multi-speed motors. Tables are used because motors need to be changed out at times and the branch circuit components need to be large enough to handle the new motor that is being installed to replace the old motor. If motor nameplate were used and a very high efficiency motor were installed the first time, the motor branch circuit components might not be rated high enough if a standard motor were installed in place of the high efficiency motor.

Support Pillars Acceptable as Ufer GEC? 41. Can the concrete pillars used to support a manufactured home be used for the UFER grounding electrode? Reference: NEC 250.52(A) Answer: Probably not if the pillars are installed in the usual manner, that is, from concrete blocks on the earth surface. To qualify, a pillar would need to meet the description of a grounding electrode in 250.52(A).

MC and outlet boxes in raised floor of IT room 42) For power distribution units (PDU s) inside a room designated information technology with field installation using MC to 4plex receptacle boxes under the floor, is it required to secure and support the boxes and wiring methods as stated in 645.5(E)(2)? Or, would this installation meet the requirements in 645.5(F)? Reference: NEC 645.5 (E)(2) and 645.5(F) and 300.11 Answer: Possibly If the assembly is not listed as IT Equipment or for IT Equipment the MC cable and boxes must be secured in place in accordance with 300.11. 300.11 requires them to be fastened in place without using ceiling/floor support wires as the means of support. If the assembly is listed as IT Equipment or for IT Equipment the assembly is not required to be secured in place.

PV Inverters with AFCI Protection 43. Since there is only one inverter that is third party listed as being arc-fault protected, should the requirements of NEC 690.11 be enforced for all inverters therefore only approving 1 type that has many restrictions? IE.. Only 3-5kws are listed? Reference: 690.11, 90.4, (QIDC) Pg. 325 UL WB Answer: Actually up to 11 KW are Listed for SMA Solar under the product category PHOTOVOLTAIC DC ARC-FAULT CIRCUIT PROTECTION (QIDC) located on page 325 in the 2012 UL White Book. If there aren t sizes available for an installation under 90.4 the AHJ under special permission may permit products that complied with the previous version of the Code.

Aircraft Hangars 44) In a small aircraft hanger where the aircraft has its fuel tanks in its wings is it allowed to have electrical outlets on the side walls by the wings for servicing the aircraft? Reference: NEC 513.3 & 513.4 Answer: Yes see section 513.3 & 513.4 513.3 Classification of Locations: (A) Below Floor Level Class I, Division 1 or Zone 1 (B) Areas Not Cut Off or Ventilated. The entire area Class I, Division 2 or Zone 2 location up to a level 18 in. above the floor. (C) Vicinity of Aircraft.

513.3(C) Vicinity of Aircraft: (1) Aircraft Maintenance and Storage Hangars. The area within 1.5 m (5 ft) horizontally from aircraft power plants or aircraft fuel tanks shall be classified as a Class I, Division 2 or Zone 2 location that shall extend upward from the floor to a level 1.5 m (5 ft) above the upper surface of wings and of engine enclosures.

Aircraft Hangars 44) In a small aircraft hanger where the aircraft has its fuel tanks in its wings is it allowed to have electrical outlets on the side walls by the wings for servicing the aircraft? 513.4 Wiring and Equipment in Class I Locations. Requires all wiring and equipment installed in or operating within Class I locations defined in 513.3 are required to meet the applicable provisions of Article 501 or Article 505 for the division or zone in which they are used. Attachment plugs and receptacles in Class I locations shall be identified for Class I locations or shall be designed such that they cannot be energized while the connections are being made or broken.

45. In an operating room that has been identified as a wet procedure location can a regular receptacle trim plate be used? Reference: 517.19(A) Answer: YES

517.2 Definitions: Critical Care Areas Those special care units, intensive care units, coronary care units, angiography laboratories, cardiac catheterization laboratories, delivery rooms, operating rooms, and similar areas in which patients are intended to be subjected to invasive procedures and connected to line-operated, electro-medical devices.

517.2 Definitions: Wet Procedure Locations Those spaces within patient care areas where a procedure is performed and that are normally subject to wet conditions while patients are present. These include standing fluids on the floor or drenching of the work area, either of which condition is intimate to the patient or staff.

517.19 Critical Care Areas (A) Patient Bed Location Branch Circuits Emergency system receptacles shall be identified and shall also indicate the panelboard and circuit number supplying them.

2014 NEC 517.19(C) (new) (C) Operating Room Receptacles. (1) Minimum Number and Supply. Each operating rooms shall be provided with a minimum of thirty six receptacles

45. In an operating room that has been identified as a wet procedure location can a regular receptacle trim plate be used? Answer: YES

Tap Rules/ No Rounding up 46. Is it permissible to use 240.4(b) and round up to the next standard size over current device on a feeder tap? Example; Can 23 feet of 500 kcmil, Type THHN/THWN copper conductors be tapped off of a 1200 ampere feeder and terminated on a 400 amperes main breaker in a subpanel? Reference: 240.21(B) Feeder Taps. Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1) through (B)(5). The Provisions of 240.4(B) shall not be permitted for tap conductors. Answer: No. Ampacity of 500 kcmil is 380 amperes, so it cannot be used to terminate into a 400 ampere main breaker for either the 10 foot tap or the 25 foot rule.

Use of Dusttight J-Boxes on Class II, Div 1 Areas 47. Are dusttight Hoffman type junction boxes with Meyers Hubs listed for use in a Class II Division I location approved for use in a Class II, Division I location as a pull through only box when sized correctly even though the box is not identified for use in a Class II location, but listed dusttight only? Reference: 502.10(A)(4) (Class II, Div. 1) Fittings and boxes shall be provided with threaded bosses for connection to conduit or cable terminations and shall be dusttight. Fittings and boxes in which taps, joints, or terminal connections are made, or that are used in Group E locations, shall be identified for Class II locations. Answer: A pull box without taps, joints, or terminal connections, is acceptable in the Class II Division 1 area if dusttight.

Show window at a Bank? 48) Where a freestanding bank is built having about 75% full length windows mostly for security reasons. Is it required to have the contractor install show window receptacles? Reference: NEC 100 (Definitions) and 210.62 Answer Maybe Show Window. Any window used or designed to be used for the display of goods or advertising material, whether it is fully or partly enclosed or entirely open at the rear and whether or not it has a platform raised higher than the street floor level 210.62 Show Windows. At least one receptacle outlet shall be installed within 450 mm (18 in.) of the top of a show window for each 3.7 linear m (12 linear ft) or major fraction thereof of show window area measured horizontally at its maximum width Will they use reader boards, or other signage in the windows? Do they advertise using the windows?

Cord Connected Water Heater 49. Can a 30-amp water heater use a cord connector and receptacle as the disconnecting means? Reference: 110.3(B),(KSDT) Pg. 235 UL White Book, UL 174 Answer: No, see Household Water Heaters, Storage Tank (KSDT) which states that these water heaters are intended for household use and permanent connection to the supply source in accordance with the NEC. UL 174, permits only small capacity water heaters (5 gal. or less) to be cord and plug connected.

Sunroom AFCI Requirements 50) Why are sunrooms specifically listed to be AFCI protected but not an enclosed porch or patio? Reference: NEC 210.12(A) Answer: 210.12(A) Dwelling Units. All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arcfault circuit interrupter, combination-type, installed to provide protection of the branch circuit. 210.52(A) General Provisions. In every kitchen, family room, dining room, living room, parlor, library, den, sunroom, bedroom, recreation room, or similar room or area of dwelling units, receptacle outlets shall be installed in accordance with the general provisions specified in 210.52(A)(1) through (A)(3). IRC: Sunroom Addition: A one-story structure added to an existing dwelling with a glazing area in excess of 40 percent of the gross area of the structure s exterior walls and roof.

National Electrical Code Forum Your Questions Answered

Meet Your Distinguished Experts Moderator: Mike Forister Cheyenne, Wyoming John Benson Electrical Engineer-Ft Collins, CO Steve Conrad Program Administrator DORA-Denver, CO Don Iverson Midwest Field Rep, NEMA, CMP 1-Mason, MI Alan Manche Schneider Electric-, CMP 10, Lexington, KY Chuck Mello Underwriters Laboratories, CMP 5-Milwaukie, OR John Stacey Western Section President, CMP 6-St Louis, MO

Junction Box Size 51. What is the minimum size of junction box that can be installed to enclose a power distribution block that measures 6 x 6 and has two parallel 3/0 AWG copper conductors per phase terminated on both sides of the block? Reference: NEC 314.28(E) with 314.28(A)(2) and Table 312.6(A) Answer: NEC 314.28(E) permits power distribution blocks in boxes over 100 cubic inches with wiring handling, routing, and termination restrictions per 312.6. Table 312.6(A) requires minimum bending space of 4 inches for the #3/0 conductors. With the 6 inch power distribution block and with conductors terminated at both sides, the minimum width of the box would be 6+4+4 = 14 inches. Also note that dimensions must meet installation instructions for the power distribution block.

Water Pipe Bonding Methods 52. Can I bond the waterline to a sub panel ground bar and not at the main panel if the incoming waterline is plastic and the house waterline is copper? If so, what size wire do I need to bond it with if I ve fed the house with 4/0 aluminum? Reference; 250.104(A)(1)(2)(3) No, (1) states the water line must be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to one or more grounding electrodes used. #(2) and #(3) do not apply to the installation described. The bonding conductor is sized per 250.66 (4 AWG cu. Or 2 AWG al.)

Question #53 AFCI Protection A Proven Safety Device. 550.25 states that AFCI protection is required and shall comply with 210.12. Why then do these leave the factory without the AFCI protection installed in the panels? Answer: NO. Title 24 HUD 3280.801 Scope. (a) Subpart I of this part and Part II of Article 550 of the National Electrical Code (NFPA No. 70 2005) cover the electrical conductors and equipment installed within or on manufactured homes and the conductors that connect manufactured homes to a supply of electricity.

Question #53 AFCI Protection Answer Continued: (b) In addition to the requirements of this part and Part II of Article 550 of the National Electrical Code (NFPA No. 70 2005), the applicable portions of other Articles of the National Electrical Code must be followed for electrical installations in manufactured homes. The use of arc-fault breakers under Articles 210.12(A) and (B), 440.65, and 550.25(A) and (B) of the National Electrical Code, NFPA No. 70 2005 is not required. However, if arc-fault breakers are provided, such use must be in accordance with the National Electrical Code, NFPA No. 70 2005. Wherever the requirements of this standard differ from the National Electrical Code, these standards apply.

Question #54 Fire Pumps If I have a separate underground service for a fire pump entering the fire pump controller at the nearest point of entry and the controller has a disconnecting means built into it (they are all service rated by code), do I need a additional disconnecting means ahead of the controller?

Question #54 Fire Pumps Answer: 2011 NEC: An additional disconnect means is not required. The connection being described is considered a direct source connection per 695.4(A). See below. Article 695 permits fire pump source connections to be either direct or through a disconnecting means (695.4(B)). 695.4(A) Direct Connection. The supply conductors shall directly connect the power source to either a listed fire pump controller or listed combination fire pump controller and power transfer switch. Note: Fire pumps are typically considered three wire motor loads so be sure the fire pump controller is ordered with a neutral if installed on a grounded system. NEC 250.24(C) requires the grounded conductor be brought to the service equipment

Size of Grounded Service Conductor 55. What would be the minimum size of grounded service conductor that would be required for an industrial facility with a 2000 ampere service consisting of 5 parallel runs in 5 conduits of 600 kcmil Type THWN- 2 copper conductors? (there are no neutral loads on the system).

Size of Grounded Service Conductor Answer - Based on the information in the question the minimum required size would be 1/0 copper or 3/0 aluminum in each raceway. Even though there are no phase to neutral loads from the service, 250.24(C) would require the installation of grounded service conductors (neutrals) to the service equipment. Again since there are no neutral loads, then calculation of neutral conductor size from 220.61 would not be required. Section 250.24(C) does specify a minimum sizing in accordance with (C)(1) or (C)(2) for either single raceway or multiple raceways respectfully. With multiple raceways 250.24(C)(2) would require the size be based on the size of the ungrounded conductors in each raceway using Table 250.66 and not smaller than 1/0 AWG.

Main Power Feeder / Paralleled? 56. Is it permissible to utilize Table 310.15(B)(7) and install two parallel runs of 4/0 aluminum SER cable for a 400 ampere main power feeder for a single family dwelling? Reference: NEC 310.15(B)(7) Answer: No, this section requires that the conductors be the main power feeder (not feeders) A 400 ampere service requires 400 kcmil copper or 600 kcmil aluminum as provided in the Table 310.15(B)(7).

Disconnect Access 57. An RTU is placed on a metal frame for weight dissipation & built up to where the controller and the breaker (disconnect) is now 8 AFF. Is it required to install a working platform 30 x 36 or is a ladder to access and service the unit NEC compliant using the exception to 404.8 exception (2) & 240.24(a)(4) Reference: NEC 404.1 with 404.8, Exception No. 2 Answer: The circuit breaker disconnect location for the RTU is governed by NEC Article 404 per NEC 404.1. With the disconnect mounted at the elevated RTU equipment, access by portable means (ladder) is allowed by NEC 404.8, Exception No. 2 in lieu of a service platform.

58. I have two Islands in my house, one is for the kitchen and one is for my wet bar in another room. They both have a receptacle within 6 of the sink installed on the back side of the island. The inspector is requiring that the one for the wet bar be GFCI protected and not requiring that for the kitchen. Is that a proper interpretation of the 2011 NEC? Reference: GFCI PROTECTION NEC 210.8 (A)(6)(7) Answer: It depends on the placement of the island outlet in the kitchen area. If the outlet is located low and is NOT intended to serve the countertop surfaces the inspectors interpretation is correct per 210.8(A)(6). The island outlet for the other wet bar must be GFCI protected per 210.8(A)(7).

Question #59 Commercial Garages Can PVC conduit be installed under the floor of a Commercial Garage (NEC 511) and if so with what restrictions?

Question #59 Commercial Garage Answer: Yes. In 511.4 (A) Wiring and Equipment in Class I Locations shall conform to the applicable provisions Art 501. 501.10 Wiring Methods (A) (1) (a) Exception; Type PVC conduit and type RTRC conduit shall be permitted where encased in a concrete envelope a minimum of (2 in.) thick and provided with not less than (24 in.) of cover measured from the top of the conduit to grade. Where this exception is used, threaded rigid metal conduit or threaded steel intermediate metal conduit shall be used for the last (2ft) of the underground run to emergence or to the point of connection to the aboveground raceways, and a equipment grounding conductor shall be included to provided electrical continuity of the raceway system and for grounding of non-current-carrying metal parts

Question #60 Can a service be located beneath the down spout or over flow scupper of a building? Answer: No. See NEC 230.54(G). (G) Arranged That Water Will Not Enter Service Raceway or Equipment. Service-entrance and overhead service conductors shall be arranged so that water will not enter service raceway or equipment.

Conductors Withstand Ratings 61. How is it NEC compliant to have a #8 Supply side bonding jumper and 4-#3cu on the line side of a 100a service disconnect (which may be one of 6 justifying the large transformer)being fed from a 500kva 13.2 KV to a 208v utility transformer? Would any of these conductors hold up in a ground fault or short circuit situation? Is this an area that requires a code change?

Conductors Withstand Ratings Answer - Assuming a transformer impedance of 5 percent and an unlimited supply the available 3 phase short circuit current at the transformer is 27,750 Amps. This would be reduced to some lower value at the service equipment based on the length and size of the service conductors. For estimating purposes, the ground fault current imposed on the 8 AWG copper supply side bonding jumper would be about 33% of the 3-phase value or about 9000 Amps. The current withstand rating of 8 AWG copper for 9000 Amps is 2 to 3 cycles and fuses or circuit breakers rated 100 Amps would clear this level of fault in 1 to 2 cycles. The 3 AWG copper conductors would withstand the 27,000 Amps for 2 to 3 cycles so the same would apply to these conductors under full bolted fault short circuit conditions. This is already covered by the requirements in 110.9 and 110.10.

Ampacity/Adjustment/Correction/Termination 62. What is the maximum allowable ampacity for (6) 3 AWG THHN copper current-carrying conductors installed in EMT in an ambient temperature of 110 F. and terminated in 60 C. lugs? Reference: NEC 110,14(C), 310.16(B)(16) 310.15(B)(2)(a) and (3)(a) 110.14(C) states that we can use the rating of the conductor (THHN is 90 degree) ampacity for adjustment and correction factors however the final ampacity cannot exceed the lowest temperature rating of any connected termination. Since the terminations are 60 degree the ampacity is limited to 85 amperes in Table 310.15(B)(16) in the 60 degree column. 310.15(B)(16) allows 115 amps for a 3 AWG THHN in the 90 degree column. 310.15(3)(a) requires an 80% ampacity adjustment for 6 current carrying conductors. 115 x.80 = 92 amperes. 310.15(B)(2)(a) requires a correction factor of.87 for 110 degree ambient temperature in the 90 degree column..87 x 92 = 80 as the maximum allowable ampacity. 80 amps are less than 85 amps therefore meeting the 60 degree requirement of 110.14(C)

Farm Demand Load 63. What is the total demand load in kva for a farm with a 30 kva dwelling, a 10 kva barn and a 3 kva storage shed? Reference: NEC 220.103 with Table 220.103 Answer: For farm load calculation on a common electrical service with a dwelling, Table 220.103 may be used for the farm loads that are added to the 30 KVA dwelling demand load. The resulting calculation will be : 30 KVA + (10 KVA x 1.00) + (3.0 x 0.75) = 30+10+2.25 = 42.25 KVA

Smoke Detector Requirements 64) Do wireless interlocked smoke detectors meet the building code requirement for interlocking smoke detectors in dwelling units, or must they be hard wired? Smoke detector requirements are not in the NEC. Placement, power supply, and interconnection requirements are in the building code.

Smoke Detector Requirements SECTION R314 SMOKE ALARMS R314.1 Smoke detection and notification. All smoke alarms shall be listed in accordance with UL 217 and installed in accordance with the provisions of this code and the household fire warning equipment provisions of NFPA 72. R314.2 Smoke detection systems. Household fire alarm systems installed in accordance with NFPA 72 that include smoke alarms, or a combination of smoke detector and audible notification device installed as required by this section for smoke alarms, shall be permitted. The household fire alarm system shall provide the same level of smoke detection and alarm as required by this section for smoke alarms. Where a household fire warning system is installed using a combination of smoke detector and audible notification device(s), it shall become a permanent fixture of the occupancy and owned by the homeowner. The system shall be monitored by an approved supervising station and be maintained in accordance with NFPA 72.

Smoke Detector Requirements Exception: Where smoke alarms are provided meeting the requirements of Section R314.4. R314.3 Location. Smoke alarms shall be installed in the following locations: 1. In each sleeping room.2. Outside each separate sleeping area in the immediate vicinity of the bedrooms.3. On each additional story of the dwelling, including basements and habitable attics but not including crawl spaces and uninhabitable attics. Indwellings or dwelling units with split levels and without an intervening door between the adjacent levels, a smoke alarm installed on the upper level shall suffice for the adjacent lower level provided that the lower level is less than one full story below the upper level. When more than one smoke alarm is required to be installed within an individual dwelling unit the alarm devices shall be interconnected in such a manner that the actuation of one alarm will activate all of the alarms in the individual unit.

Smoke Detector Requirements R314.3.1 Alterations, repairs and additions. When alterations, repairs or additions requiring a permit occur, or when one or more sleeping rooms are added or created in existing dwellings, the individual dwelling unit shall be equipped with smoke alarms located as required for newdwellings. Exceptions: 1. Work involving the exterior surfaces of dwellings, such as the replacement of roofing or siding, or the addition or replacement of windows or doors, or the addition of a porch or deck, are exempt from the requirements of this section. 2. Installation, alteration or repairs of plumbing or mechanical systems are exempt from the requirements of this section.

Smoke Detector Requirements R314.4 Power source. Smoke alarms shall receive their primary power from the building wiring when such wiring is served from a commercial source, and when primary power is interrupted, shall receive power from a battery. Wiring shall be permanent and without a disconnecting switch other than those required for overcurrent protection. Smoke alarms shall be interconnected. Exceptions: 1. Smoke alarms shall be permitted to be battery operated when installed in buildings without commercial power. 2. Interconnection and hard-wiring of smoke alarms in existing areas shall not be required where the alterations or repairs do not result in the removal of interior wall or ceiling finishes exposing the structure, unless there is an attic, crawl space or basement available which could provide access for hard wiring and interconnection without the removal of interior finishes.

Question #65 AFCI Protection An old interior service panel is used as a junction box. The branch circuits are extended to a new exterior service panel. Are the branch circuits identified in NEC 210.12(A) required to be arcfault protected?

Question #65 AFCI Protection Answer: Yes 210.12 (B) Branch Circuit Extensions or Modifications Dwelling Units. In any areas specified in 210.12(A), where branch-circuit wiring is modified, replaced, or extended, the branch circuit shall be protected by one of the following: (1) A listed combination-type AFCI located at the origin of the branch circuit. (2) A listed outlet branch-circuit type AFCI located at the first receptacle outlet of the existing branch circuit.

Question #66 Is it a violation to install a bollard for protection of a panel which violates the working clearances while the bollard is in place but where the nuts can be removed with a simple tool to work on the panel and have the required clearances while you are servicing the panel?

Question #66 Answer: The AHJ will have to decide if the bollard and steps to remove it, allow access to the working space. NEC 110.26(E)(2) recognizes that such protection is required for outdoor equipment. NEC 110.26(E)(2) Outdoor. Outdoor electrical equipment shall be installed in suitable enclosures and shall be protected from accidental contact by unauthorized personnel, or by vehicular traffic, or by accidental spillage or leakage from piping systems. The working clearance space shall include the zone described in 110.26(A). No architectural appurtenance or other equipment shall be located in this zone. 110.26 Spaces About Electrical Equipment. Access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment.

Garage PV System 67. A solar photovoltaic system is installed on a detached garage which has a 30A sub-panel and 3-wire feeder so the grounded conductor is bonded to the grounding electrode system (ground rod) at the garage. The PV system is larger than the conductors can carry for a grid-tie system so the PV grid-tie conductors were run back to the main structure s main panel. The PV inverter is grounded to the grounding electrode system of the detached garage. Since the garage has only a 3-wire system the grounded conductor was isolated to avoid a parallel path and the equipment ground with the PV grid-tie conductors was upsized to accommodate the two systems. Is this legal?

Garage PV System Answer - Maybe. With the feeder from the inverter back to the main building and service having an equipment grounding conductor the exception in 250.32(A) is no longer valid. The connection of the inverter grounding electrode conductor to the garage grounding electrode would be required by 250.58. Therefore the neutral in the garage panel would have to be isolated from the enclosure and the grounding electrode conductor. The only way the single equipment grounding conductor can serve both the inverter feeder and the garage feeder is if it was installed in the same raceway or trench using 250.122(C). If the feeders are in separate raceways then the neutral would have to be isolated and an equipment grounding conductor from the service panel to the garage panel would have to be installed per 250.32(A).

Cords in Class 1 Locations 68. Can car lifts in a commercial garage be wired with cords? Reference: NEC 511.4 501.140 Answer: Not unless there is a reason for flexibility or portability

Luminaire Construction 69. Is a sconce with an open top considered guarded? Reference: NEC 100 Guarded Answer: No, the open-top sconce would not be considered guarded. While the specific application is not indicated, the definition of guarded in Article 100 requires items to be Covered, shielded or otherwise protected to remove the likelihood of approach or contact by persons or objects to a point of danger. The open top on the sconce would not meet that requirement of protection.

Carbon monoxide Detector Requirements 70) In Colorado, where are carbon monoxide detectors required in a dwelling unit and must they be 120-volt with battery back-up. Also, are they required to be interlocked with other interlocked smoke detectors in a dwelling unit? Carbon monoxide detector requirements are not in the NEC. Placement, power supply, and interconnection requirements are in the building code.

Carbon monoxide Detector Requirements SECTION R315 CARBON MONOXIDE ALARMS R315.1 Carbon monoxide alarms. For new construction, an approved carbon monoxide alarm shall be installed outside of each separate sleeping area in the immediate vicinity of the bedrooms in dwelling units within which fuel-fired appliances are installed and in dwelling units that have attached garages. R315.2 Where required in existing dwellings. Where work requiring a permit occurs in existing dwellings that have attached garages or in existing dwellings within which fuel-fired appliances exist, carbon monoxide alarms shall be provided in accordance with Section R315.1.

Carbon monoxide Detector Requirements R315.3 Alarm requirements. Single station carbon monoxide alarms shall be listed as complying with UL 2034 and shall be installed in accordance with this code and the manufacturer's installation instructions.

Question #71 Smoke Alarms What is the minimum distance a smoke detector may be installed from the door of a bathroom containing a shower in a dwelling unit?

Question #71 Smoke Alarms Answer: NEMA Standard SB 11 2011 provides general guidance. In damp or excessively humid areas, or next to bathrooms with showers. Tiny droplets can accumulate inside the sensing chamber and make the detector overly sensitive. A tremendous amount of humid air is produced during a hot shower. The moisture in this humid air can enter the sensing chamber as water vapor, then cool and condense into droplets that can cause a nuisance alarm. NFPA 72-2010 and 2013 prohibits a smoke alarm or detector from being installed within 36 inches from a door leading to a bathroom containing a shower or tub.

Question #72 Circuit Breakers Are branch circuit breakers marked SWD and rated for 480 volts suitable for switching fluorescent lighting loads? Answer: Yes, see NEC 240.83(D). (D) Used as Switches. Circuit breakers used as switches in 120-volt and 277-volt fluorescent lighting circuits shall be listed and shall be marked SWD or HID. Circuit breakers used as switches in high-intensity discharge lighting circuits shall be listed and shall be marked as HID. UL Whitebook - CIRCUIT BREAKERS, MOLDED CASE AND CIRCUIT- BREAKER ENCLOSURES (DIVQ) - Circuit breakers marked "SWD" and rated 347 V or less are suitable for switching fluorescent lighting loads on a regular basis at their rated voltage.

Installation of MRI Equipment 73. Manufactures of MRI machines have been adamant about there not being any metallic pathways out of the MRI room that could cause interference with the imaging. They spec an isolation coupling in the conduit of the branch circuits into the room. How are inspectors supposed to deal with this issue in regards to 517.13?

Installation of MRI Equipment Answer - The only circuits that should be going into the shielded MRI room are those directly related to the MRI equipment. Generally all the MRI circuits go through a special isolation panel in the wall of the special room to shield any outside coupling that could create interference to the magnetic imaging equipment as well as any of the magnetic energy to leave the room. Lighting circuits in the ceiling should be higher than where these would fall under 517.13. If the circuits are those related to the MRI equipment assembly directly, that equipment is covered under its listing and these are not building construction circuits that would be subject to 517.13 just as internal wiring in other medical equipment in a patient care area are not subject to this provision. That listing includes specific provisions for assurance of equipment grounding to the single point grounding reference to assure proper operation of the MRI equipment.

Wet Location / Weather-Resistant Receptacle? 74. A low volt panel installed outside has a receptacle inside; does this receptacle need to be WR Reference: 406.9(B)(1) Answer: Yes, 15- and 20-ampere, 125- and 250-volt receptacles installed in a wet location shall have an enclosure that is weatherproof whether or not the attachment plug cap is inserted. All 15- and 20-ampere, 125- and 250-volt nonlockingtype receptacles shall be listed weather-resistant type.

Range Demand Load 75. What is the demand load for (20) 8 kw ranges installed in a multi-family dwelling? Reference: NEC 220.55 with Table 250.55. Answer: Use of Column C in Table 220.55 is to be utilized for determination of loads. Note 3 permits exception primarily for loads on multiple cooking units within dwelling units. The demand load for 20 ranges rated at 8 KW is 35 KW as indicated in Column C.

Equipotential bonding in livestock containment areas. 76) Are the stock holding pens (with concrete floors) of a slaughter house facility required to have the equipotential plane bonded? There are stock tank heaters in the pens and chutes. The rails and posts are steel. Article 547.10 (A)(B) As there are electrical devices and concrete floors in the livestock containment area equipotential plane bonding is required. Minimum 8 AWG SOLID conductor required.

Question #77 Barriers Answer: 300.3(C) (1) Conductors of Different Systems. (1) 600 Volts, Nominal, or less. Conductors of ac and dc circuits, rated 600 volts, nominal or less shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway. Informational Note #1: See 725.136(A) for class 2 and Class 3 circuits conductors.

Question #77 Barriers Answer Continued: Art. 725.136(A) Separation from Electric Light, Power, Class 1 ect. (A) General: Cables and conductors of Class 2 and Class 3 circuits shall not be placed in any cable, cable tray, compartment, enclosure, manhole, outlet box, raceway, or similar fitting with conductors of electric light, power, Class 1, non-powered broadband communications circuits unless permitted by 725.136(B) through (I).

Question #77 Barriers Answer continued: Art. 725.136(B) Separated by Barriers. Class 2 and Class 3 circuits shall be permitted to be installed together with the conductors of electric light, power, Class 1, non-power-limited fire alarm and medium power networkpowered broadband communications circuits where they are separated by a barrier.

Question #78 690.14 states that the ac disconnect is not required to be suitable for service equipment. Would the AC disconnect for a line side tap be required to be suitable for service equipment? Answer: No. SUSE is not required. If this is a utility interactive application the requirements for the point of connection are found in NEC 690.64. In the 2011 NEC, these requirements were appropriately moved to Article 705 such that NEC 690.64 simply sends you to NEC 705.12.

Question #78 Answer Continued: 690.64 Point of Connection. Point of connection shall be in accordance with 705.12. 705.12(A) Supply Side. An electric power production source shall be permitted to be connected to the supply side of the service disconnecting means as permitted in 230.82(6). The sum of the ratings of all overcurrent devices connected to power production sources shall not exceed the rating of the service. Also see 705.20,21.22 for the disconnect requirements SUSE is not a requirement.

Transformer Feeder Installation 79. We have a facility that owns the 13k step down to 208v transformer that is normally owned by the utility. The transformer is located in the basement of the building in a retirement center. With fault currents over 30k, Is it legal to use the 25 tap rule per 240.21(C)( 6) and run EMT over head to the 208v MDP or should these secondary conductors be treated as service conductors and installed to be outside the building by a permitted method?

Transformer Feeder Installation Answer - The transformer as described as owned by the facility would mean this is a separately derived system and that there is a service to the facility at 13KV with all related service equipment. The wiring from the transformer to the 208 Volt MDP is a feeder and the various feeder tap rules in 240.21(C) would be applicable. These conductors would have short circuit and high level ground-fault protecting provided by the primary protections device. The overload protection is provided by the secondary overcurrent device(s). Being in the basement, I am assuming this is not a vault that would be considered outside the building. So, with these assumptions the transformer secondary conductor rules for 10 foot, 25 foot etc. distances would could be applied depending on meeting the specific requirements for each of the allowed installations. This feeder could be installed in EMT from the basement to the MDP following the proper wiring methods from Chapter 3.

Selection of Ampacity 80. What is the ampacity of (8) 6 AWG THHN copper current-carrying conductors installed in EMT that have a total length of 75 feet, but of which 8 feet pass through a boiler room with an ambient temperature of 120 F.? Reference: NEC 310.15(A)(2) 310.(B)(16) 310.15(B)(2)(a) and (3)(a), 110.14(C) Answer: We can start the calculation using the rating of the conductor according to 110,14. 310.15(B)(16) allows 75 amps for a # 6 THHN in the 90 degree column. 310.15(B)(3)(a) requires an 80% adjustment factor for 8 current-carrying conductors. 80% of 75 = 60 amps. 310,15(A)(2) States; Where more than one ampacity applies for a given circuit length, the lowest value shall be used. Because 10 ft. or 10% of the circuit runs through 120 degree boiler room a correction factor of 82% is required from 310.15(B)(2)(a) 60 x.82 = 49 amperes allowed. This does not exceed the 60 degree ampacity of 55 amperes meeting the requirements of 110.14(C).

Water Heater Circuit 81. What is the minimum size branch circuit allowed for a 4500 watt, 240-volt, 40 gallon water heater? Reference: NEC 422.13, 210.19(A), and 240.4(D)(7) Answer: Under NEC 422.13, storage type electric water heaters are to be considered continuous loads with a resulting demand factor of 1.25 for sizing branch circuits per 210.19(A). Using the unit element size of 4,500 watts (volt-amperes) at 240 volt, 1-phase, the calculated demand load is: (4,500 x 1.25) / 240 = 5,625 / 240 = 23.4; rounded to 23 amperes Using NEC 240.4(D)(7), the #10 AWG minimum conductor size would be selected with overcurrent protection at 30 amperes.

Use of NM-B cables in barns. 82) Is NM-B cable allowed to be used in any area of a barn? Article 547.1 The provisions of this article shall apply to the following buildings or that part of a building or adjacent areas of similar or like nature as specified in 547.1(A) or (B). There are may be some areas of a barn where NM-B is acceptable for use. Where NM-B is installed the requirements of Article 334 must be used.

Question #83 Information Technology Equipment Can a field installed receptacles and wiring methods be considered listed for information technology equipment per 645.5G (B) to not have to secure and support under the raised floor? What would be an example of where you have to secure & where you do not have to secure receptacles and wiring methods from a PDU under a floor?

Question #83 Information Technology Equipment Answer: NO. 645.5(E) Branch-circuit conductors installed under the raised floor of an ITE room using any of the wiring methods listed in 645.5(E)(2) are required to conform to the specific article for the wiring method used. In addition, Article 300 applies, except where modified by Article 645. For example, 300.11 requires raceways, cables, and boxes to be securely fastened in place, even though they are installed below a raised floor. 645.5(F) Securing in Place. Power cables; communications cables; connecting cables; interconnecting cables; and associated boxes, connectors, plugs, and receptacles that are listed as part of, or for, information technology equipment shall not be required to be secured in place.

Question #84 For a 120v phase to phase isolated power system supplying receptacles in a hospital operating room. Is it required to install bonding bushings or bonding locknuts on the EMT entries to the 4 square boxes or is a standard locknut sufficient? Answer: Yes, bonding bushing or bonding locknuts are required. NEC Article 358 permits EMT to be used as an equipment grounding conductor when installed as a system and appropriate fittings are used. Article 517.13(A)/(B) set the requirements for using a metal raceway system which qualifies as an equipment grounding conductor and an insulated equipment grounding conductor to the receptacle/box.

Question #84 Answered Continued: 517.19(D) Equipment Grounding and Bonding. Where a grounded electrical distribution system is used and metal feeder raceway or Type MC or MI cable that qualifies as an equipment grounding conductor in accordance with 250.118 is installed, grounding of enclosures and equipment, such as panelboards and switchboards, shall be ensured by one of the following bonding means at each termination or junction point of the metal raceway or Type MC or MI cable: (1) A grounding bushing and a continuous copper bonding jumper, sized in accordance with 250.122, with the bonding jumper connected to the junction enclosure or

Fault Current Limiting 85. Is it NEC compliant per 110.3 to reduce the fault current by using let through current up over down method to protect a standard breaker panel? Is this an approved method per UL?

Fault Current Limiting Answer - No. The short circuit current available at the line terminals cannot exceed the Short Circuit Current Rating of the panel. Where the quick calculation shows a possible Short Circuit Current higher than the rating, then a more detailed short circuit study or calculation needs to be done to include all wire impedances and the true available current at the supply transformer. If the fault current calculated still exceeds the rating of the panel, then either the panel will need to be replaced with one with suitable ratings or some other means, such as inserting an impedance, to reduce the flow through fault current. A current limiting fuse using the up-over-down method is not an acceptable alternative.

Splices in LB? 86. How many #14 wires can I splice in a ¾ LB that is labeled with 6.5 cubic inches? Reference: NEC 314.16(C)(2) Conduit Bodies With Splices, Taps, or Devices. 314.14(B) Answer: Only those conduit bodies that are durably and legibly marked by the manufacturer with their volume shall be permitted to contain splices, taps, or devices. The maximum number of conductors shall be calculated in accordance with Table 314.16(B). Table 314.16(B), shows a 14 AWG as being 2.00 cubic in. The LB is 6.5 cubic inches divided by 2.00 = 3 # 14 AWG allowed, 2 that are spliced and one passing through.

Office Demand Load 87. What is the lighting load in VA for a 10,000 sq. ft. office building, including general purpose receptacles, where the number of general purpose receptacles is unknown? Reference: NEC 220.12, Table 220.12, and 220.14(K) Answer: The minimum General Lighting Load for an office facility is designated in Table 220.12 as 3.5 volt-amperes (VA) per square foot (VA/SF). In addition, the general receptacle load where not available from 240(I) is designated as 1.0 VA/SF in 240.14(K). The calculation for combined general lighting and receptacle loads is: 10,000 x (3.5 + 1.0) = 10,000 x 4.5 = 45,000 VA

Protection from physical damage. 88) Does the code specify protection from damage requirements or does the authority having jurisdiction make his own requirements [ as for NEC 110.26 [E] The AHJ always has the last say. That said there are a few areas in the code where physical protect is required such as Article 334.15 (B), (C).

Question #89 Conduit Bodies What kind of devices are allowed in a conduit body (referred to in 314.16(C)(2)? Answer: There is not a conduit body made with a mounting yoke inside it. When 314.16(C)(2) mentions devices, they refer to all electrical devices. As you recall an electrical device is a device that either produces, consumes, or directs (receptacles) electricity. Some would even say a wire nut is a device.

Question #90 Is it required to install a disconnecting means on each light pole since it is defined as a structure by the code making panel? Answer: No, see NEC 225.32 Exception No. 3 225.32 Exception No. 3: For towers or poles used as lighting standards, the disconnecting means shall be permitted to be located elsewhere on the premises.

Rebar Connections 91. Since rebar can simply be tie wired together and this is approved for the UFER. Can a CU conductor simply be tie wired to the rebar?

Rebar Connections Answer - No. 250.70 requires the connection of the grounding electrode conductor to the grounding electrode using exothermic welding or a suitably listed lugs, listed pressure connectors, listed clamps, or other listed means. For a connection device to be embedded in concrete it must also be listed and identified for direct burial and/or concrete encasement. Listed devices suitable for connection of grounding electrode conductors can be found under UL Category Code KDER on page 217 of the 2012 UL White Book. Tie wires are not a listed device nor specifically allowed by 250.70.

Corner Grounded Delta / Grounded Phase? 92. On a corner grounded delta service, is the grounded leg required to be in the A, B or C phase location? Reference: Schneider-Electric - Definitions Answer: Corner-Grounded Delta System A system in which the transformer secondary is delta-connected with one corner of the delta solidly grounded. Corner-grounded delta systems are also referred to as grounded B phase systems, grounded phase services, and end-grounded delta systems

Ground Ring Electrode 93. What is the minimum size copper grounding electrode conductor allowed to connect to a ground ring? Reference: NEC 250.52(A)(4) and 250.66(C) Answer: The minimum size of a ground ring encircling a building or structure shall be #2 AWG per NEC 250.52(A)(4). The minimum size for the bare copper grounding electrode conductor is established in NEC 250.66 as the values shown in Table 250.66, except as permitted in paragraphs 250.(A), (B), and (C). The grounding electrode conductor under 250.66(C) is allowed to be the same size of the conductor for the ground ring or thus #2 AWG, (unless a larger ground ring is installed).

Outlet spacing/wall spaces. 94) Is a receptacle on 24 wall located behind the swing of a door required? Article 210.52(A)(2)(1) Yes an outlet is required on the wall space. Any space 2 feet or more in width and unbroken along the floor line by doorways and similar openings, fireplaces, and fixed cabinets.

Question #95 Conduit Bodies What length of a C Conduit body is required for #4 wire pulled in a 2 conduit? Answer: 314.28 Pull and Junction Boxes and Conduit Bodies. Boxes and conduit bodies used as pull or junction boxes shall comply with 314.28(A) through (E). (A) Minimum Size. For raceways containing conductors of 4 AWG or larger that are required to be insulated, and for cables containing conductors of 4 AWG or larger, the minimum dimensions of pull or junction boxes installed in a raceway or cable run shall comply with (A)(1) through (A)(3). Where an enclosure dimension is to be calculated based on the diameter of entering raceways, the diameter shall be the metric designator (trade size) expressed in the units of measurement employed. (1) Straight Pulls. In straight pulls, the length of the box or conduit body shall not be less than eight times the metric designator (trade size) of the largest raceway.

Question #96 I have a 200A service on a residence fed with 4/0 aluminum and a 100A sub panel. What size SER cable do I need to run to the sub panel? The requirements for using SE type cable for feeder and branch circuit wiring are found in NEC Article 338. In particular to this question, NEC 338.10(B)(4)(a) covers indoor installations of this cable and includes requirements for cases where the cable is installed in thermal insulation. See the second paragraph from this section below: Where installed in thermal insulation, the ampacity shall be in accordance with the 60 C (140 F) conductor temperature rating. The maximum conductor temperature rating shall be permitted to be used for ampacity adjustment and correction purposes, if the final derated ampacity does not exceed that for a 60 C (140 F) rated conductor.

Question #96 Answered Continued: Since this installation does not qualify as a main power feeder per NEC 310.15(B)(7), use of the table 310.15(B)(7) is not permitted and all of the requirements of NEC 310.15 will apply in sizing the SER cable for this installation. Case 1: SER installed in thermal insulation, 40 C ambient. From Table 310.15(B)(16), using 60 C column, a #1 Cu or 1/0 Al size would be the minimum size required but we must check for any adjustment or correction factors. Checking for ambient adjustment, Table 310.15(B)(2)(a) requires a 0.91 adjustment for 40 C ambient. Since SER cable has a temperature rating of 90 C we can use that column from table 310.15(B)(16) so 145 A X 0.91 = 132A Cu and 135 x 0.91 = 123 A Al. #1 CU or 1/0 AL is required for this feeder.

Question #96 Answered Continued: Case 2: SER NOT installed in thermal insulation, 40 C ambient. SER cable is listed as an assembly for 75 C so from Table 310.15(B)(16), a #3 Cu or #1 Al size would be the minimum size required but we must check for any adjustment or correction factors. For the adjustment and correction factors, the temperature rating of the conductors can be used, 90C. Checking for ambient adjustment, Table 310.15(B)(2)(a) requires a 0.91 adjustment for 40 C ambient. Using the 90 C column from table 310.15(B)(16) so # 3 Cu - 115 A X 0.91 = 105A and #1 Al - 115 x 0.91 = 105 A. #3 CU or #1 AL is required for this feeder.

Structural Steel Grounding Electrode 97. We have a precast building that has multiple areas, separated by the precast, containing a steel framework of beams and bar joists. The building has a 2/0 counterpoise ground system surrounding it in a ring with multiple ground rods. The lightning protection system is bonded many times to this ground, as well as the main service grounding electrode system. Building steel in each of these separate areas is also bonded to the counterpoise ground. Can the building steel be considered a grounding electrode and be used to bond the separately derived system transformers without having to run all the way back to the main service?

Structural Steel Grounding Electrode Answer - The building steel would be considered a grounding electrode conductor or common grounding electrode conductor per 250.68(C). Since the building steel is bonded to the overall grounding electrode system, then it would qualify and be suitable for use to ground the separately derived systems.

NM Cable / 60 or 90 degree? 98. When the sheathing is removed from NM cable, can you treat the individual conductors as THWN or is it still NM cable? Reference: NEC 334.80 Ampacity Answer: It s still NM cable; the conductors are unmarked and would be rated for 60 degree.. The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The allowable ampacity shall not exceed that of a 60 C (140 F) rated conductor. The 90 C (194 F) rating shall be permitted to be used for ampacity adjustment and correction calculations, provided the final derated ampacity does not exceed that of a 60 C (140 F) rated conductor

Fault Current Rating 99. On an existing commercial building a portion of the tenant space is being remodeled. During a rough electrical inspection, the service is looked at and the breakers do not have a high enough AIC rating for the available fault current. Can the inspector require the service or any of the panels being used Reference: NEC 90.4, 110.10, 110.22, and 110.24 Answer: Under the provisions of NEC 110.10, 110.22, and 110.24, the design and application of individual system components is to be provided as needed to withstand the affects of short circuit current under fault conditions. Where an existing installation is found deficient or improperly installed, the Authority Having Jurisdiction (AHJ) has the responsibility of enforcement and determination of approval of equipment and materials, as defined in NEC 90.4. In this case, the extent and depth of such action that is required is at the discretion of the AHJ.

Carbon monoxide Detector Requirements 100) In Colorado, where are carbon monoxide detectors required in a dwelling unit and must they be 120-volt with battery back-up. Also, are they required to be interlocked with other interlocked smoke detectors in a dwelling unit? Carbon monoxide detector requirements are not in the NEC. Placement, power supply, and interconnection requirements are in the building code.