Impact of Bonding Requirements for CSST on

LP-Gas Piping Systems

April 2009

• 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

• 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 PE pipe with copper tracer wire– 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 Damage

Arcing damage possible to all gas piping materials

Copper tracer wire will be energized and arc to PE

Increase and maintain minimum physical separation distance

• 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

Grounding Requirements

Grounding not required for LP storage containers.

Grounding Electrode System

Various types of electrodes permitted

Grounding electrode conductor and bonding conductor are different

Do not install separate electrode for LP-gas service

Lightning Protection System

Protects structure

LPS effective against indirect strikes through its grounding electrode system

Lightning activity varies around country

Bonding of underground metallic piping required by NFPA 780

Lightning Induced CSST Damage

Arcing damage impacts all gas piping materials

CSST does not fail due to lightning induced voltage levels

Thinner pipe wall is a contributing factor

• 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

6.9.3.15 LP-Gas piping shall not be used as a grounding electrode. (also NFPA 54 and 70)

6.22.1.3 Grounding and bonding shall not be required on LP-Gas systems.

7.13.4 Lightning Protection Systems. Where a lightning protection system is installed, the bonding of the gas piping shall be in accordance with NFPA 780.

NFPA 780 requires the bonding of any underground conductive piping to the grounding electrode system at or near the entry point into the structure.

NFPA 58/54/70/780 Requirements

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

Equipment Grounding Conductor

EGC 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 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 and outdoors.

Same proposal submitted for 2011 NFPA 58.

Commercially available

- Union

- Shut-Off Valve Combo

Installed upstream of pressure regulator and above ground

Only required if underground piping is metallic

Dielectric Fittings

Complete Piping System

- Tubing

- Fittings

- Strike Plates

Update ANSI Standard

Installed in accordance with manufacturer’s instructions

Uniform bonding practices

Impact on CSST Piping Systems

Ward Mfg - Wardflex

Parker - ParFlex

Omegaflex - TracPipe

Titeflex - Gastite

Truflex - Pro-Flex

MetalFab - Diamondback

Six Manufacturers: One Approach

• 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 second stage regulator (at service entrance)

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

• 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 fitting

Attached to pipe or pipe component per the clamp listing

Never attach to corrugated tubing itself

Insure 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

• 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.

• New CSST bonding requires dielectric isolation• 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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