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Electrical Protection of CSST Gas Piping Systems
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
CSST Product Standard
Electrical Protection of CSST Gas Piping Systems
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
Electrical Protection of CSST Gas Piping Systems
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]
Electrical Protection of CSST Gas Piping Systems
6
Grounding Electrode
Underground Pipe
Electric Power Line
Metallic Appliance Vents
Electrical Protection of CSST Gas Piping Systems
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]
Residential Fire Statistics*
Electrical Protection of CSST Gas Piping Systems
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
Electrical Protection of CSST Gas Piping Systems
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.
Unintended Consequences
Electrical Protection of CSST Gas Piping Systems
Lightning does not discriminate. It seeks all pathways to ground. It will damage all mechanical/electrical systems.
Electrical Protection of CSST Gas Piping 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.
Electrical Protection of CSST Gas Piping Systems
• 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
Electrical Protection of CSST Gas Piping Systems
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
Electrical Protection of CSST Gas Piping Systems
Nationally recognized standards No requirements for lightning
resistance No prescribed national test method
for lightning resistance Same for mechanical and electrical
equipment
Product Standards
Electrical Protection of CSST Gas Piping Systems
• Underground metallic piping not used as grounding electrode
• Require dielectric fitting before POD • No grounding/bonding required on underground piping or container
15
NFPA 58 (2011 and 2014)
Electrical Protection of CSST Gas Piping Systems
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
Electrical Protection of CSST Gas Piping Systems
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
Electrical Protection of CSST Gas Piping Systems
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
CSST Manufacturer’s Bonding Requirements
Electrical Protection of CSST Gas Piping Systems
Bond at the most convenient
location within the house with the shortest practical conductor length.
Electrical Protection of CSST Gas Piping Systems
Bonding Clamp* Attachment
* Bonding Clamps listed to UL 467
Electrical Protection of CSST Gas Piping Systems
Bonding Requirements
Gas piping systems that contain one or more segments of CSST shall be bonded.
Electrical Protection of CSST Gas Piping Systems
Bonding Connections
Gas piping shall not be used as a grounding electrode
Electrical Protection of CSST Gas Piping Systems
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
Electrical Protection of CSST Gas Piping Systems
• 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
Who Does the Bonding?
Electrical Protection of CSST Gas Piping 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.
Electrical Protection of CSST Gas Piping Systems
Lightning entry point Equi-potential bonding Bonding location Length of conductor Proximity of other pathways Grounding electrode system Code requirements
Bonding Effectiveness Factors
Electrical Protection of CSST Gas Piping Systems
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
Electrical Protection of CSST Gas Piping Systems
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
NFPA 54 (2015 in process)
Electrical Protection of CSST Gas Piping Systems
Arc-Resistant Jackets
• Conductive jacket • Arc energy absorbed • Listed to ICC bench standard • Protection up to 5 Coulombs
33
WARDFLEX II
Electrical Protection of CSST Gas Piping Systems
Arc-Resistant Protective Jacket is Fully Tested*
[* No product is immune from lightning damage.]
0.1
1
10
100
1000
0.00001 0.001 0.1Arc
Char
ge in
Cou
lom
bs
Duration of Arc in Seconds
Arc-Resistant
Yellow CSST
Electrical Protection of CSST Gas Piping Systems
CSST Safety Campaign
• PERC gas customer mail insert • SFM public service announcements
• Partnership with NAIC • AHRI Model legislation - Home Inspectors
• PERC DIY Campaign
Electrical Protection of CSST Gas Piping Systems
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
Summary