ECN Forum

250.104

Posted By: BigB

250.104 - 02/13/19 01:16 AM

I have a local inspector challenging a bonding method we have been using. Many times when we replace a service on an older dwelling the gas is closer than the water, sometimes a lot closer. In order to avoid running 50-100 feet of GEC all the way to the water we simply run to the house side of the nearby gas service then jumper the gas and water pipes at the water heater. Today I was told that we are in violation as we must run to the water as our "primary" bond was how it was put. I cannot find reference to this in the code unless he is interpreting 250.104(1) differently than I am. It does not say the water pipes must be bonded directly to the service equipment etc etc, just that they be bonded to it which in my interpretation they are.
Posted By: ghost307

Re: 250.104 - 02/13/19 12:57 PM

A gas pipe must be bonded to the electrical service, but it is not permitted to use it as a ground conductor.
You need to run a legal grounding conductor (sized per the relevant table) back to the Service point.

This has been the case for many years; it sounds like this is just the first time that an AHJ noticed and red tagged it.
Posted By: BigB

Re: 250.104 - 02/13/19 01:23 PM

Originally Posted by ghost307
A gas pipe must be bonded to the electrical service, but it is not permitted to use it as a ground conductor.
You need to run a legal grounding conductor (sized per the relevant table) back to the Service point.

This has been the case for many years; it sounds like this is just the first time that an AHJ noticed and red tagged it.

Can you reference a code article that clarifies that? Also as far as an AHJ noticing it, it was recommended by one of the city inspectors about 8 years ago and we point it out on every inspection with no objections until yesterday.
Posted By: HotLine1

Re: 250.104 - 02/13/19 02:09 PM

250.104 (B) commentary within the 2014 NEC Handbook provides a detailed explanation of the bonding of metalic gas piping systems. I am aware that the commentary is NOT 'Code', however it does provide an explanation.
Posted By: ghost307

Re: 250.104 - 02/13/19 03:51 PM

See NFPA 70 Sec. 250-104(b) and NFPA 54 [Sec. 3.14(a)].

NEC 250-104(b) requires you to bond the aboveground portion of a metal gas piping system to a grounding electrode system for safety reasons. NFPA 54; Sec. 3.15 does not allow you to use aboveground portions of a metal gas piping system or its components as a conductor in electrical circuits.

The difference between Grounding and Bonding leads to a lot of confusion.
The gas pipe needs to be Bonded to the Service Ground so that it maintains the same potential as the electrical system. This is done at a single point. If the gas pipe is used as part of the grounding path there is the risk that current could flow along a pipe that contains a flammable gas.

Saying that the gas line needs to be Grounded is a common holdover from when the differences between Bonding and Grounding were not clearly defined.
Posted By: HotLine1

Re: 250.104 - 02/13/19 05:56 PM

Ghost:
Thanks for that. I did not have time to compose the details that you stated.

Bonding & grounding are misunderstood by many.
Posted By: BigB

Re: 250.104 - 02/14/19 12:22 AM

Originally Posted by ghost307
See NFPA 70 Sec. 250-104(b) and NFPA 54 [Sec. 3.14(a)].

NEC 250-104(b) requires you to bond the aboveground portion of a metal gas piping system to a grounding electrode system for safety reasons. NFPA 54; Sec. 3.15 does not allow you to use aboveground portions of a metal gas piping system or its components as a conductor in electrical circuits.




Thanks for the info, very helpful. Looks like I learned something today.
Posted By: gfretwell

Re: 250.104 - 02/16/19 06:08 PM

You still need a supplemental electrode if you are using a water pipe.

Quote

250.53(D)(2) Supplemental Electrode Required. A metal underground
water pipe shall be supplemented by an additional electrode of
a type specified in 250.52(A)(2) through (A)(8)
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