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Bonding size for CSST #204895 01/19/12 06:52 PM
Joined: Aug 2005
Posts: 250
Trick440 Offline OP
Hey guys...

So what I have here is bonding of Corrugated Stainless Steel Tubing (gas line manifold) . I say a #8 solid is ok. Inspector comes in and says the building inspector wants a #6.

Not sure if I agree. Electrical inspector said to contact the building inspector and see about getting that overturned.

Can you guys give me your thoughts on this and maybe an angle I can go forward with when talking to the building inspector?

On a sided note; I would usually just change it out to the #6, but we have already done 3 houses this way and have many more to do. Its cost effective to get this straight. This is also in the beautiful city of Detroit, where copper gets stolen all the time. So the less copper the better.

Shake n Bake
Building Codes & Related References
Re: Bonding size for CSST [Re: Trick440] #204896 01/19/12 06:59 PM
Joined: Aug 2005
Posts: 250
Trick440 Offline OP
I should really use the search feature before posting. It looks like I do need to run a #6.

Originally Posted by HotLine1

"CSST Bonding Ė What is Required?
There is confusion on what is going on with CSST,
flexible gas piping, since the manufacturers have been
sending out revised installation instructions with their
material. The revisions were a result of a lawsuit in which
the court stated that the manufacturers must provide a
means to protect the CSST from lightning. The revised
instructions are requiring that the CSST be bonded to the
grounding electrode conductor.
The installation instruction requirements are not
in compliance with the currently adopted codes. The code
requires that CSST be bonded, not grounded or used as a
grounding electrode. Section 250.104(B) of the 2005
National Electrical Code (NEC) states that the equipment
grounding conductor is permitted to serve as the bonding
means for the gas piping. Otherwise, bonding is required
to be from the CSST connector coupling to the water piping.
The size of the bonding conductor is based on the rating
of the circuit likely to energize the piping system. Table
250.122 in the 2005 NEC provides the conductor size
based on the ampacity of the circuit. For example, if there
is a gas heater with no electric at all to it and the service to
the dwelling is 200 amperes, Table 250.122 states that 6
AWG copper or 4 AWG aluminum is required for the
bonding conductor.
The clamps installed on the water and CSST pipes
must be listed and labeled in accordance with Section 250.8
of the 2005 NEC. The clamps may be a dissimilar metal,
provided they are approved and listed for the use.
In conclusion, no additional bonding is required
where there is electric to any gas appliance, since Section
250.104(B) of the 2005 NEC permits the equipment
grounding conductor to serve as the bonding means for a"(gas piping system.


Last edited by Trick440; 01/19/12 07:00 PM.

Shake n Bake
Re: Bonding size for CSST [Re: Trick440] #204911 01/20/12 11:28 PM
Joined: Sep 2004
Posts: 6
Mills Offline
New Member
Yeah, I'm surprised how smoothly that requirement was foisted upon us. It irks me that a gas pipe manufacturer can rush a product to market before adequate R&D, and then when it fails, force another trade to fix their problem.

But the end may be in sight? A mechanical contractor told me a coupla weeks ago that they are going to stop making the yellow stuff.

Since CSST bonding is not addressed by the NEC, to get the specifics, here is what is required in our area:
"It shall be the responsibility of the Mechanical contractor to provide the electrical
contractor and the electrical inspector the installation instructions for each and every
CSST piping installation."

Re: Bonding size for CSST [Re: Trick440] #204914 01/21/12 01:21 PM
Joined: Nov 2007
Posts: 763
KJay Offline
I think maybe this is similar to the situation for smoke alarms and smoke detectors. The NEC doesnít specifically require them, but our state building code does and also specifies their location as well as the type of sensors used.
Seems to be basically the same thing now with CSST. IMO, other than whatís addressed in 250.104[B], itís not really an NEC issue, so much as a building code and plumbing code issue. Here we just run a #6 CU bonding conductor to the gas piping manifold or location where the gas piping changes over from black iron to CSST. Our state actually banned using CSST for a short time until manufactures addressed the problem of lightning strike damage, so this seems to be the solution the manufactures came up with, and what the state building and plumbing code Deptís accepted.

Re: Bonding size for CSST [Re: Trick440] #204963 01/25/12 04:18 PM
Joined: Apr 2002
Posts: 7,237
HotLine1 Offline
I guess it's better late than never...
I finally got around to getting this from our Plumbing Inspector, who got this at a recent seminar.

From the IFGC (International Fuel Gas Code, 2009)
310.1.1 CSST.
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 6AWG copper wire or equivalent.

That is probably where the inspector in the OP obtained the #6 size from.

Jurisdiction here (NJ) is the Electrical Inspector, and a NJ Lic EC is required to do the install and obtain the permit for same.

Re: Bonding size for CSST [Re: Trick440] #204980 01/26/12 01:34 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
This can get to be interesting, as the other AHJ - the gas utility - tends to get nervous when you start attaching wires to the gas pipes.

I understate the case ... here the GasCo quite bluntly says gas lines are NOT to be grounded. There's a mighty fine distinction between 'grounding' and 'bonding.'

In any event, since we are talking about the returning of static electricity to Mother Earth, we ARE discussing grounding, and not bonding. Mitigating lightning damage (grounding) has nothing to do with clearing faults (bonding).

Since the grounding electrode system is always carrying some current, I can understand why the GasCo gets touchy about sparks flying when the open a gas fitting. Unlike the plumbing, you're not likely to find insulating unions on a gas line.

Re: Bonding size for CSST [Re: Trick440] #204987 01/26/12 04:45 PM
Joined: Apr 2002
Posts: 7,237
HotLine1 Offline

I'm 100% with ya on this, but I have no choice as this is written.

We (NJ) used to use "gas piping is bonded via the EGC in the appliance" (My words, not the way it was written) This was a subject of many heated debates.

Basically, now, IF CSST is installed the gas pipe installer is required to have a Lic EC pull a permit for the bonding/grounding install, and have that inspected by electrical inspector. To date...I have seen zero.

Re: Bonding size for CSST [Re: HotLine1] #204995 01/27/12 01:10 PM
Joined: Nov 2007
Posts: 763
KJay Offline
I see that Mike Holt sent out a newsletter today with a link to yet another article that outlines the problem of lightning strikes and the resulting fires that seems to have plagued CSST since its beginning. In the article they mention that they have seen some problems even where the gas tubing was properly bonded, so that doesnít sound too promising.

CSST Article

Re: Bonding size for CSST [Re: Trick440] #204996 01/27/12 01:46 PM
Joined: Jul 2004
Posts: 9,575
gfretwell Offline
I can't get past the ad.

Maybe the answer is to parallel the CST with a bonding wire, connected at each joint, to keep everything at the same potential from end to end. I do not know of any code that says that tho.

Greg Fretwell


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