Bonding and Installation Requirements for CSST

Gas Piping Systems

April 2009

• A conducting connection between an electrical circuit or equipment and the earth that limits the voltage imposed upon it. Only the premise wiring system is grounded.

• The permanent joining of metallic parts to form an effective electrical path that ensures continuity and the capacity to safely conduct any current likely to be imposed. Gas piping is bonded.

Grounding verses Bonding

Grounding Requirements

Grounding system limits power surge and lightning energy

Grounding required at transformer as well as house

NEC requirement

• Ave. number lightning flashes/year in US: 25,000,000

• Average annual number of U.S. home fires* by cause: - Fires caused by lightning: 4,800

- Fires caused by natural gas: 2,100 - Fires caused by lightning/fuel gas: 180 - Fires caused by lightning/wires: 260 - Fires caused by electric distribution: 24,000

Lightning damage to gas piping is an uncommon event compared to other causes of fires.* NFPA data

Lightning Statistics

• Insulation failure on power circuit wiring• Unintentional contact with higher voltage line• Direct lightning strike on the structure• Lightning that branches from nearby strike• Lightning energy conducted through the soil and

underground metallic systems or through overhead power lines

• Lightning current takes all pathways of electrical resistance to ground and not just the path of “least resistance”.

Energizing Metallic Piping Systems

• Lightning does not discriminate. It will damage all piping materials and systems.

• Damage is attributed to arcing caused by a difference in voltage build-up between the grounded electrical system and any other electrically conductive pathway.

• Gas system components typically damaged:– Perforations of CSST wall– Flow/loss of pipe dope between threaded joints– Failure of flexible connectors on steel pipe system– Failure of copper tubing/pipe– Failure of gas burning equipment components

Lightning Induced Piping Damage

Lightning Induced CSST Damage

Arcing damage impacts all gas piping materialsCSST does not fail due to lightning induced voltage levelsThinner pipe wall is a contributing factor

NFPA 780: Lightning Protection System

Protects structure

LPS effective against indirect strikes through its grounding electrode system

Lightning activity varies around country

Bonding of underground metal piping required by NFPA 780

Contributing Construction Factors• Metallic duct work not typically bonded• Elimination of other metallic pathways:

–No copper water pipe (use of PEX)–Less or no coax cable (wireless communications)–Non-metallic plumbing vents and drains

• Replacing masonry chimneys with metallic appliances vents – new lightning pathway that energizes wire, duct and pipes

• Increase robustness of bonding connection beyond minimum required by NEC.

• Bonding at service entrance to divert energy off gas piping system and lower voltage level.

• Increase jumper size to reduce the difference in voltage build-up between other electrically conductive pathways and minimize potential for arcing.

• Equi-potential bonding of all metallic systems will further reduce the chances for arcing by balancing the voltage levels in all connected systems.

• Maintain physical separation as much as practical

CSST Solution

Applicable Codes and Standards

250.104(B): Other Metallic Piping: Where installed in or attached to a building or structure, metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122 using the rating of the circuit that is likely to energize the piping system(s).

The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means.

Section 250.104(B) only deals with electrical energy at 60-Hz and only provides ground fault protection.

NEC Bonding Requirements

Grounding Electrode SystemVarious types of electrodes permitted

Grounding electrode conductor and bonding conductor are different

Do not install separate electrode for gas service

Equipment Grounding ConductorEGC sized to protect against ground faults

12 AWG wire not able to carry electrical energy from lightning

12 AWG wire not able to respond to lightning frequencies

2009 Bonding Requirements*

CSST gas piping systems shall be bonded to the electrical service grounding electrode system at the point where the gas service enters the building. The bonding jumper shall not be smaller than 6 AWG copper wire or equivalent.

* 2009 NFPA 54, IFGC and UPC

2009 IFGC Electrical Isolation

404.8.1 Isolation. Metallic piping and metallic tubing that conveys fuel gas from an LP-gas storage container shall be provided with an approved dielectric fitting to electrically isolate the underground portion of the pipe or tube from the above ground portion that enters a building. Such dielectric fitting shall be installed above ground, outdoors.

Proposal submitted for 2011 NFPA 58.

• CSST manufacturer has no enforcement power.• Reliance on product listing and manufacturer’s

instructions varies. • State/local code may not be in sync with national

model codes.• NEC Section 110.3(B) and NFGC Section 1.1.2

defers to the manufacturer’s instructions for listed equipment if code not clear.

• Subject to interpretation by local AHJ.

Local Code Enforcement

Complete Piping System- Tubing- Fittings- Strike Plates

Update ANSI Standard Installed in accordance with manufacturer’s instructionsUniform bonding practices

Impact on CSST Piping Systems

Ward Mfg - WardflexParker - ParFlexOmegaflex - TracPipeTiteflex - GastiteTruflex - Pro-FlexMetalFab - Diamondback

Six Manufacturers: One Approach

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are needed to see this picture.

Technical Bulletins

• Direct bonding of CSST to the grounding system is now required

• All new CSST installations for all gas appliances • One-size-fits-all for most residential applications• Installation and sizing requirements consistent with NEC

Section 250 for metallic piping and current edition of NFGC

• Installed by person recognized by AHJ as qualified to perform such work

• Do not bond any underground metallic piping upstream of utility meter

CSST Bonding Instructions

• One simple, universal bonding approach

• Effective and low cost• Consistent with NEC/NFGC

requirements• Applies to all single family

and low-rise multi-family• Commercial applications

may require an engineered solution

KISS Principle

• Electrical service equipment enclosure

• Grounded conductor at the electrical service

• Grounding electrode conductor

• Grounding electrode

Direct Bond Connection

• Customer side of meter• Downstream of 2nd stage

LP regulator• Indoors or outdoors• Upstream of first CSST

fitting

Bond Near the Gas Service

Bond Upstream of 1st CSST Fitting

Multi-Meter Bonding

• At least a 6 AWG copper wire or equivalent

• Installed in accordance with NEC

• Jacketed or bare• Above or below grade• Keep as short as possible

Bonding Jumper

Attachment Points

Between meter and first CSST fittingAttached to pipe or pipe component per the clamp listingNever attach to corrugated tubing itselfInsure metal-to-metal contact between clamp and sub-surface

• Listed to national standard

• UL 467• Attached in accordance

with NEC 250.70 and listing

• Always accessible

Bonding Clamp

• Avoid using other metallic systems for support

• Avoid direct contact with other metallic systems

• Avoid co-locating CSST with metallic appliance vents

Avoid Physical Contact

• Plumbing inspector must look for presence of bonding on new systems and reject system without proper connection. Alert plumbing contractor of requirement.

• Electrical inspector must inspect to NEC minimum (250.104B) and in accordance with the CSST manufacturer’s instructions.

• On retrofit jobs, plumbing inspector must either notify electrical inspector or inspect bonding.

Inspector Responsibility

• Direct bonding of gas piping will:– Lower voltage levels– Reduce differences in electrical potential– Minimize the possibility of arcing

• Maintain physical separation where practical• Bonding together of all metallic systems• All CSST products require the same type of

bonding in accordance with current edition of NFPA 54 or IFGC or UPC

Summary

• No code or standards requirements mandating lightning resistance, protection or mitigation.

• New bonding requirements above minimum of NEC.• Direct bonding will reduce impact of lightning strikes on

gas piping system without effecting ground-fault protection.

• CSST industry requiring direct bonding on all new CSST installations with a “keep-it-simple” approach.

• National model code change proposals are being developed.

• CSST product standard being updated.

Conclusions

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