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I had a licensed natural gas tech/plumber install a new branch line using CSST to a new fireplace. When I am asked him about bonding it, he said he had never heard of that before. From everything thing I've read, bonding seems necessary (to avoid damage to the CSST from lightning strike or otherwise stray electrical charge). What I can't wrap my head around is this: If the gas line is bonded to the electrical panel (circuit breaker service entrance) which is bonded to the water supply from the street (just a lead pipe (yes, we still have lead here) that runs through the ground), how is this different from the gas pipe which already is a metal pipe running through the ground? It seems that the gas pipe is already grounded by virtue of being buried. If I put what seems like an additional ground on the gas pipe, don't I run the risk of other charges on the grounding system running through the gas pipe to discharge instead of the water pipe?

  • Here is a video that shows what CSST looks like and how ground bonding would happen. This is not an attempt to answer - just to explain more about what is being asked. – JPhi1618 Nov 21 '19 at 16:42
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    Natural gas distribution is often done with poly pipe -- it could easily be the case that the riser coming from the ground to your meter is metal (and is wrapped or painted, ie electrically insulated, to protect against corrosion) but it quickly transitions to plastic and thus provides no meaningful grounding. – Greg Hill Nov 21 '19 at 16:49
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The pipe only needs to be bonded at 1 place, usually this is at the meter. If it is bonded there the entire system is attached to a grounding bond and would be legal.

The gas pipe is bonded to prevent it from becoming electrified by a short. It cannot be used as a grounding electrode but the grounding electrode system needs to be attached someplace after the gas meter. I would check there as that is where the bond is usually located.

If you have lead pipes I would want to drive supplemental ground rods and get rid of the lead pipes (I hope you don’t drink the water). The reason to have a pair of additional driven grounding electrodes is a good idea for what happened to a tract of homes in my area. All the old pipe was removed and new non metallic pipe installed. A customer called because getting shocked. I discovered she had no ground and the pipe was plastic up to the house. Their utility did this to every home and the only grounding electrode was the water pipe. After installing a pair of rods she quit getting shocked. If that same case happened to you your gas pipe would end up being your electrode not safe and a code violation.

  • The gas meter is inside the house and wasn't bonded. I ended up clamping the black metal pipe before the CSST and running a #6 into the grounding system on the circuit breaker panel. The city is in the process of replacing all the lead pipes so in the near future, I'll have to drive in a grounding rod and move the grounding wire from the panel over to this. Thanks for the help. – Michael C Nov 25 '19 at 13:24
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I wouldn't touch the CSST with a 10-foot pole. It is thin-walled, and any clamping method would risk puncturing it.

I would ground the chassis of the appliance, just as I might any large metal appliance whether it ran on wood fuel or steam!

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    Indeed, the manufacturer only specifies grounding clamps for the fittings and says never to clamp to the actual pipe under any circumstances. – JPhi1618 Nov 21 '19 at 21:59

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