Welcome DISCLAIMER. Testing Electric Fire Pumps You Need to Understand the Arc Flash Hazard 5/1/ NFPA Conference & Expo

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1 2017 NFPA Conference & Expo Testing Electric Fire Pumps You Need to Understand the Arc Flash Hazard Presented by: Tracey D. Bellamy, PE, CFPS Chief Engineering Officer Telgian Corporation Welcome Instructor Tracey D. Bellamy, PE, CFPS Chief Engineering Officer Tracey is Chief Engineering Officer with Telgian Corporation and has 30 years of experience in Fire Protection Engineering. He serves on a number of NFPA Committees, including NFPA 13, 15, 16, 25, 30, 30B, 101 and 5000 as well as a major contributor to the NFPA 13 and 25 Handbooks. He is a Senior instructor with NFPA. He holds professional engineering licenses in 49 of the 50 states and all of the US Territories. He is an active member of both NFPA and SFPE. DISCLAIMER This seminar and its content is not a formal interpretation issued pursuant to NFPA regulations. Any opinion expressed is the personal opinion of the author and presenter and does not necessarily present the official position of the NFPA and its Technical Committees. Furthermore, this presentation is neither intended, nor should be relied upon, to provide professional consultation or services. 1

2 Electrical Hazard A dangerous condition such that contact or approach to energized conducts or equipment failure can result in a: Shock Hazard Electric Shock Arc Flash Hazard Arc Flash Burn Thermal Burn Blast Extent of hazard determined through risk assessment Electrical Hazard Electrical Hazard 2

3 Electrical Safety Legal Mandate: 29 CFR U.S.C. 654(a)(1) Electrical Safety More detail provided by: NFPA 70E, Electrical Safety in the Workplace Referenced in NFPA 25 Electrical Safety 1 st Choice and Safest Alternative Put equipment in an electrically safe working condition De energize equipment Determine all sources of power Open disconnecting device(s) Visually verify disconnect(s) are open, if possible Apply lockout/tagout(s) Use proper test instrument to verify equipment is de energized 3

4 Fire Pump Disconnect NFPA 20 and the NEC permit a single disconnecting means between the source of power and the controller/transfer switch where the disconnect is: Suitable for service entrance Lockable in closed and open position Separated from other building or FP disconnects Marked as FP Disconnecting Means Supervised in open position Placard at the controller Fire Pump Disconnect NOT Required to be installed Very few fire pump installations include a disconnect Fire Pump Disconnect Without a disconnecting means: Power would have to be pulled at the suppling transformer Certainly not within the purview of the typical water based fire system inspector Typically requires utility company to complete Not Being Done!!! 4

5 Fire Pump IT&M Inspection, Testing and Maintenance (IT&M) of fire pumps is required in accordance with NFPA 25 Fire Pump IT&M NFPA 25 provides for the following annually with respect to IT&M work on an electric fire pump controller: Voltage and current levels must be taken on all lines at all flow test points conditions with the pump operating Older electric fire pump controllers (prior to the 1999 Edition of NFPA 20) do not include external means to take such readings As a result readings will generally include entry into a energized controller unless remote read equipment is used Fire Pump IT&M NFPA 25 provides the following annually with respect to IT&M work on an elec. fire pump controller: Electrical connections need to be checked and repaired (tightened) as needed PCB s need to be checked for corrosion Power and control cable/wire need to be checked for cracking Plumbing parts inside the electrical panel need to be checked for leakage water on electrical parts Could all be done with the controller de energized 5

6 Electrical Safety NFPA 70E/OSHA does permit work on energized equipment where: Shutdown would introduce additional hazards or increased risk Task to be performed is infeasible in de energized condition due to design or operational issues Electrical Hazard 1.2 cal/cm 2 2 nd Degree Burn Shock Hazard Boundaries Arc Flash Boundary Shock Hazard Limited Approach Boundary Shock hazard exists Restricted Approach Boundary Increased likelihood of shock hazard exists Required distances dependent on operating voltage and fixed/movable conductor type NFPA 70E, Table 130.4(D)(a) for ac systems: Typical 480V, 3 Phase electric with fixed conductor requires a limited approach boundary of 3.5 ft and a restricted approach boundary of 1 ft 6

7 Shock Hazard Only qualified persons permitted within the restricted approach boundary Only qualified persons or persons under the direction of a qualified person permitted within the limited approach boundary. All testing within the limited approach boundary must be conducted by a qualified person [NFPA 70E] Qualified Person Qualified Person One who has demonstrated skills and knowledge related to the construction and operation of electrical equipment and installations and has received safety training to identify and avoid the hazards involved. [NFPA 70E] Many state and local governments have licensing programs for electricians NICET Inspection and Testing of Water Based Systems Limited in knowledge of electrical safety Shock PPE The qualified person must be insulated or guarded from energized electrical conductors rubber insulated gloves/sleeves rated for the voltage involved as required to protect against hand/arm contact with conductors 7

8 Shock PPE Arc Flash Hazard What is Arc Flash? Rapid release of energy through an arcing fault Arcing fault between a phase bus bar and: Another phase bus bar, Neutral, or Ground 8

9 What Causes Arc Flash? Dropping tools / Accidental touching Contamination or tracking over insulated surfaces Dust Condensation Material failure Corrosion Faulty installation Arc Flash Hazard Arc Flash Hazard must be determined through the conduct of an arc flash risk assessment Must establish arc flash boundary Must establish required PPE Two methods: Use Tabular Category Values Determine incident energy levels Arc Flash Boundary/PPE Tabular Category Method: NFPE 70E, Table 130.7(C)(15)(A)(b) ac systems 480V MCC Two Entries Equipment 600 V class motor control centers (MCCs) PPE Category Arc Flash Boundary Parameters: Maximum of 65 ka short circuit current available; maximum of 0.03 sec (2 cycles) fault clearing time; working distance 18 in. 600 V class motor control centers (MCCs) Parameters: Maximum of 42 ka short circuit current available; maximum of 0.33 sec (20 cycles) fault clearing time; working distance 18 in. 2 5 ft 4 14 ft 9

10 Arc Flash Boundary/PPE Short Circuit Current: Based on power supply capacity Transformer and Feeder Connection Arc Flash Boundary/PPE Fault Clearing Time: Based on installed overcurrent protection Breakers/Fuses FP Overcurrent Protection Only overcurrent protection required by NFPA 20 is in the FP Controller Sized to have an 8 20 sec. delay at locked rotor current Sized to have a 3 min. delay at 300% of motor fullload current NO Other Overcurrent Protection Required!!! 10

11 FP Overcurrent Protection Typically the only overcurrent protection on a direct transformer connection is the primary transformer fuse FP Overcurrent Protection If additional overcurrent protection is provided it must not open: Indefinitely at locked rotor current of FP plus other connected loads Within 2 min. at 600% full load current With a restart transient of 24 times full load current Within 10 min. at 300% of full load current ALL Intended to Ensure Continuity of Power Regardless of Risk to Conductors/Equipment Arc Flash Boundary/PPE Typical Fire Pump installations do not fall within the bounds of the Tabular values for use of indicated values Must assess each location individually based on actual installation conditions to determine the specific incident energy exposure potential 11

12 Incident Energy Calculations NFPA 70E, Annex D includes four suggested methods for calculation of incident energy (3 for ac power and 1 for dc power) The use of the methods requires a through knowledge and understanding of the operating conditions at hand as well as the principals and limitations of each method AC Incident Energy Calc s Sec. Source Limitations/Parameters D.2 Lee, The Other Electrical Hazard: Electrical Arc Flash Burns D.3 Doughty, et al, Predicting Incident Energy to Better Manage the Electrical Arc Hazard on 600 V Power Distribution Systems D.4 IEEE 1584, Guide for Performing Arc Flash Energy Calculates incident energy and arc flash boundary for arc in open air; conservative over 600V and becomes more conservative as voltage increases Calculates incident energy for three phase arc on systems rated 600V and below; applies to short circuit currents between 16kA and 50 ka Calculates incident energy and arc flash boundary for; 208V to 15kV; three phase; 50Hz to 60Hz; 700A to 106,000A short circuit current; and 13 mm to 152 mm conductor gaps Arc Flash Hazard 12

13 Arc Flash Risk Assessment The results of the arc flash risk assessment must be documented The electrical equipment must be labeled to indicate: Nominal system voltage Arc flash boundary The available incident energy/working distance or arc flash PPE category required OR The minimum arc rating of clothing OR Site specific level of PPE The Owner is responsible for documentation and labeling Labeling Labeling 13

14 Labeling Labeling PPE Categories Category Minimum Arc Flash Rating 1 4 cal/cm cal/cm cal/cm cal/cm 2 14

15 PPE Categories PPE Categories PPE Categories 15

16 PPE Categories Fire Pump Examples HP Range: 40 to 150 hp Size: 750 gpm to 1,500 gpm Utility Source: 500 kva to 3000 kva Incident Energy Range: 9.82 to cal/cm 2 8 of 10 categorized as DANGEROUS Mitigation Lowering either or both the fault current or clearing time of the fault can lower the incident energy potential Cannot readily modify the fault current given that it is based on the sizing and feed from the utility transformer A reduction in clearing time can be achieved by adding upstream overcurrent protection as permitted by NFPA 20/NEC 16

17 Mitigation Implementation resulted in a significant reduction in incident energy and associated hazard Cost: Reported at ~$50,000 Alternate Mitigation Lower risk by limiting risk exposure i.e., Do not conduct inspection and testing on exposed energized electrical fire pump controller Must accept risk of potential associated with such Alternate Mitigation Ultimate purpose of completing fire pump testing: Ensure that the fire pump will reliability produce sufficient output to meet the supported demands Taking voltage and amperage reading: Establish electrical health of the system Two objectives ensure fire pump meets demands as indicated above and to identify deteriorating conditions that might impact a shortened service life of the equipment or future performance issues 17

18 Alternate Mitigation Voltage variation will impact: Torque Significant impact would show up in pump performance Motor Speed Significant impact would show up in pump performance Elevated Current (Heating) Could result in shortened life of the equipment Essentially a matter of COST BENEFIT Proposed NFPA 25 TIA A white paper has been developed and issued relative to the arc flash hazards associated with electric fire pump controllers A Tentative Interim Amendment is proposed for NFPA 25 to eliminate the conduct of work within an energized fire pump controller Many contractors have currently suspended work inside the energized fire pump controllers Facility Owners need to be aware of the hazards and address the issue as well Conclusion WHAT YOU DON T KNOW CAN HURT YOU!!!!! 18

19 Questions and Comments Contact Us Thank You! Tracey D. Bellamy, PE, CFPS Chief Engineering Officer Telgian Corporation 900 Circle 75 Parkway, Suite 680 Atlanta, GA t: F: m: NFPA Conference & Expo CEUs: To receive CEUs for this session, scan your badge at the back of the room before leaving Evaluation: Complete a session evaluation on the mobile app. (Search app store for NFPA 2017 C&E. ) Handouts: Handouts will be available via the mobile app and at nfpa.org/conference Recordings: Audio recordings of all sessions will be available free of charge via NFPA Xchange. 19