NEC 250.104 (B) Other Metal Piping (GAS)

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h1h2h3

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I have an issue with a gas furnace and gas water heater that I recently installed. NEC 250.104 (B) addresses bonding of all metal piping likely to become energized within a building. My question is: Should I run a bonding jumper (say 10Awg for a 15a line - just for less resistance) from the gas line entering the furnace to the junction box containing the branch circuit for the furnace and connect it to the circuit EGC? If so, should this jumper also connect the cold water inlet? Lastly, if this must be performed on the furnace, should it be done on the H.W.H. as well?
I've asked several other electricians and have gotten several different opinions....there seems to be great confusion surrounding this issue. Some feel that it does not have to be done bcs. by default (at the service and from the utility company) these pipes are already bonded. Others feel that it must be done to eliminate potential difference if one of the two pipes were to become energized. Others feel that this will present a larger problem if an arc on the circuit were to ignite the gas.
I figure that worse case scenario I'll leave it without the jumper for now and if the inspector wants it in he'll say so. However, I need clarity on this issue and know that if anyone will know, it'll be you guys.
Thanks. :):)
 
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Dennis Alwon

Dennis Alwon

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There may be a few issues that are causing difference in opinions.

First off if the pipe used for the furnace and the water heater is that CSST piping then it must be bonding according to the manufacturers specs. This usually entails a #6 but can be as large as 250.66 requires depending on the brand that is used.

If this is black iron pipe then the equipment grounding conductor of the circuit is enough to satisfy art. 250. BTW, I think you meant art. 250 not 240.;)
 
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h1h2h3

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Location
MA
oops!!!:roll: definitely meant 250.104 (B). is there anyway i can edit this. i don't see the icon for it.
 
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haskindm

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Location
Maryland
First of all it is much safer to bond the gas line than not. Without bonding, if the gas line becomes energized, it just stays energized until someone or something touches it which is somehow grounded. At that time you may get a spark anyway, so why not bond it so that a the fault may be cleared before someone gets hurt. Besides, a solidly bonded pipe should NOT create a spark. Loose connections make sparks, not solid connections. The code says that the piping may be bonded by the grounding conductor of the circuit which is likely to energize the pipe. This will usually be the circuit to the gas appliance if it also requires electric power such as for controls or automatic lighting. Since the circuit supplying the appliance has its grounding conductor bonded to the appliance, and the gas pipe is connected to the appliance, the gas pipe is already effectively bonded and no further bonding is needed. Many electricians assume that since the code prohibits using the gas pipe as a grounding electrode, you are also prohibited from bonding it. That is not the case and the FPN to 250.52(B) makes this clear. Also see 250.104(B) which requires gas piping that is likely to become energized be bonded.
 
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h1h2h3

Member
Location
MA
John120/240 said:
If it's an electric water heater your ground wire with the power would suffice.
If you have copper water lines you need to bond across them w/#6.
Click to expand...

its a gas water heater with a cord and plug ignition system attached to it. Wouldn't the fact that the GEC is connected to the water line mean that they're already bonded? Or would I have to still come across the gas, the hot water, and cold water with a number 6 so that i'm not relying on the plumber for the Effective ground fault current path?
 
Dennis Alwon

Dennis Alwon

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Hey 3 h's, what did you use to connect the gas lines?

The unit, IMO is not effectively grounded with cord & plug however only one unit needs to be effectively bonded. Thus if the furnace is direct wired then the gas pipe is effectively bonded thruoughout the system. No need to worry.
 
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rickgomes26

Member
I couldn't agree with Dennis and Haskind more...problem is too many inspectors having been asking for bonding of hot,cold, gas for sooo long they just want it and refuse to hear any debate to why its not needed.
BUT....If you don't want hassles from inspectors bond it...bonding jumper doesn't have to be any larger that the conductor size that's likely to engergize it.
 
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