Electrical Protection of CSST Gas Piping Systems Bob Torbin, PE Omega Flex, Inc.
Standard Yellow Arc-Resistant Black
CSST Product Standard National Standard ANSI LC-1 Performance-based standard Listed system installed in accordance with manufacturer s instructions and local code Updated (2014) include: - Revised installer training - Arc-resistant jackets - Address jacket color
Manufacturer s Design and Installation Guide 1. Used in conjunction with state and local regulations and codes 2. Defer to Design Guide if no coverage in state or local codes or regulations 3. If conflict exists, then more stringent practice should be applied 4. Frequently updated to reflect changes in codes and technology
Total lightning strokes in US per year: 43,500,000* No house, equipment or material safe from direct lightning strike Most damage from indirect strikes [*USPLN: 2005-2009]
Underground Pipe Grounding Electrode Electric Power Line Metallic Appliance Vents 6
Residential Fire Statistics* Average annual number of U.S. home fires by cause*: - All 1 & 2 family house fires: 374,000 - All fires caused by electric distribution: 22,400 - All fires caused by lightning: 4,300 - All fires caused by fuel gas: 3,280 (1050 leaks & breaks) - Fires caused by lightning/wires: 280 - Fires caused by lightning/fuel gas: 188 Lightning damage to gas piping is an uncommon event compared to other causes of fires. [* NFPA Statistical Data/NFIRS]
What are the root causes? Changes in house construction/size/location Loss of metal piping Loss of copper wire for communications Loss of metal conduit for electric wiring
Unintended Consequences Metallic appliance flue (in stead of brick/clay chimneys) which rise above the roofline. Metal vent acts like lightning rod not directly connected to the electrical grounding system.
Lightning does not discriminate. It seeks all pathways to ground. It will damage all mechanical/electrical systems.
Arcing damage impacts all metallic systems including wiring and all gas piping materials. Damage not due to lightning induced voltage levels, but due to large differential in voltage potential.
Lightning energy enters house and all metallic systems Unequal bonding of metallic systems Close proximity of metallic systems Sufficient energy to jump air gap, overcome dielectric strength of CSST jacket and burn through CSST wall Gas flame near combustible material Requirements for Arcing Fire
Model Code and Standards National Electrical Code (NFPA 70) International Fuel Gas Code Lightning Protection Std. (NFPA 780) ANSI Standards 50 states and 50 codes No requirements for lightning protection
Product Standards Nationally recognized standards No requirements for lightning resistance No prescribed national test method for lightning resistance Same for mechanical and electrical equipment
NFPA 58 (2011 and 2014) Underground metallic piping not used as grounding electrode Require dielectric fitting before POD No grounding/bonding required on underground piping or container 15
NFPA 70-Equipment Grounding Conductor EGC sized to protect against ground faults Bonding wire sized based on size of branch circuit 12 AWG wire not designed to handle large DC voltage associated with lightning
NFPA 54 (2009 & 2012) Electrical Bonding* CSST. CSST gas piping systems shall be bonded to the electrical service grounding electrode system. The bonding jumper shall connect to a metallic pipe or fitting between the point of delivery and the first downstream CSST fitting. The bonding jumper shall not be smaller than 6 AWG copper wire or equivalent. Gas piping systems that contain one or more segments of CSST shall be bonded in accordance with this section. * More changes coming in 2015 edition
CSST Manufacturer s Bonding Requirements 1) Equi-potential bonding of all metallic systems 2) Direct bonding of piping to grounding electrode system Downstream of point of delivery Single point of attachment required Bonding clamp on pipe or fitting and not on CSST tubing Conductor at least 6 AWG copper Conductor as short as practical Connect to grounding electrode system per NEC
Bond at the most convenient location within the house with the shortest practical conductor length.
Bonding Gas Systems After Point of Delivery
Bonding Clamp* Attachment * Bonding Clamps listed to UL 467
Bonding Requirements Gas piping systems that contain one or more segments of CSST shall be bonded.
Bonding Connections Gas piping shall not be used as a grounding electrode
Bond Connection to Grounding System
Bond to Intersystem Termination or Panel Box
Bonding Conductor Sizing Conductor at least 6 AWG copper or 4 AWG aluminum Conductor single or multi-strand Conductor length and gauge are inter-related, but length is not specified in the NEC
Who Does the Bonding? On new installations, bonding should be performed (and permitted) by on-site electrical contractor. On retrofit job, plumbing contractor should pull both plumbing and electrical permit, but get electrical contractor for bonding Some jurisdictions do not restrict who does bonding
Avoid Direct Contact with Metallic Systems
Ground Connection of Grounding Electrode(s) Earth resistance reading at ground rod must be less than 25 Ohms or a second driven rod must be installed. Earth resistance can vary based on soil type, season and type of electrode.
Bonding Effectiveness Factors Lightning entry point Equi-potential bonding Bonding location Length of conductor Proximity of other pathways Grounding electrode system Code requirements
Bonding Effectiveness Research Bond is effective (no arcing damage to CSST) Indirect and partial direct lightning strikes Lightning energy 8/20 and 10/350 up to 10kA No damage for long conductors (up to 150-ft) No arcing for shorter conductors (< 75-ft) Lightning entry point varied Clamp location not significant factor Multiple bonding not justified for SF house
NFPA 54 (2015 in process) Revised bonding for CSST - limit conductor length: 75-ft vs 150-ft vs unlimited - no need multiple clamp locations - clamp location anywhere along piping system - bonding additional grounding electrodes - bonding to lightning protection system 32
Arc-Resistant Jackets Conductive jacket Arc energy absorbed Listed to ICC bench standard Protection up to 5 Coulombs WARDFLEX II 33
Arc Charge in Coulombs Arc-Resistant Protective Jacket is Fully Tested* 1000 100 10 1 Yellow CSST Arc-Resistant 0.1 0.00001 0.001 0.1 Duration of Arc in Seconds [* No product is immune from lightning damage.]
CSST Safety Campaign PERC gas customer mail insert SFM public service announcements Partnership with NAIC AHRI Model legislation - Home Inspectors PERC DIY Campaign
www.csstsafety.com
Summary CSST systems used safely for 24 years according to manufacturer instructions and code requirements Training and inspection are essential elements of safe installations Lightning affects all metallic systems in the house Direct bonding is effective and will reduce impact of lightning strikes on gas piping system. Arc-resistant CSST products exist equivalent to bonding Gas industry seeking updates to building codes and standards CSST industry working on public awareness
Questions Bob Torbin Omega Flex, Inc. bob.torbin@omegaflex.net