Natural Gas Piping Bonding

[steve66]

I know the code says piping likely to be energized shall be bonded, and that can include natural gas pipe.

The code also says Natural gas piping shouldn't be used for a grounding electrode.

But if you connect the pipe to the panels ground bar to bond it, doesn't it automatically become a grounding electrode? What is the real difference between bonding it and using it as a ground? Is the only difference the wire size used to connect the gas pipe?

Steve

 

[Mr. Bill]

You bond to the water pipe for use as a grounding electrode. How would a natural gas pipe likely be energized?

 

[don_resqcapt19]

Steve,

But if you connect the pipe to the panels ground bar to bond it, doesn't it automatically become a grounding electrode?

No...the gas company will use a dielectric fitting between their underground piping and the interior piping. The prevents the gas piping from becomming a grounding electrode. Also in many areas this is no longer a problem as the underground piping is non-metallic.
Don

 

[yanici]

Steve,

No...the gas company will use a dielectric fitting between their underground piping and the interior piping. The prevents the gas piping from becomming a grounding electrode. Also in many areas this is no longer a problem as the underground piping is non-metallic.
Don

Don, do you know if this has always been the case or is it something that evolved in fairly recent times? The reason I ask is that maybe there could be some older installations that could end up with the gas pipe service acting as a grounding electrode, especially if a bond is run to the grounding system.

 

[don_resqcapt19]

I think that it is an old practice on the part of the gas companies for two reasons...one they often used cathodic protection of there lines and additional connections to earth will shut some of the protecive current, and two, for the safety of their people...opening a gas pipe when it is being used as a grounded conductor would be a big safety problem. Also older codes permitted the underground gas line to be used as a grounding electrode, but only with the permission of the gas company and the AHJ. That code section was removed in the 1990 code and replaced with the wording that is now found in 250.52(B)(1).
Don
Don

 

[stickboy1375]

You bond to the water pipe for use as a grounding electrode. How would a natural gas pipe likely be energized?

I have a well so I can't use the water pipe as a GEC, yet I still have to bond the piping system, so how is my water system likely to become energized vs gas piping?

 

[haskindm]

I have seen a water line become energized throuh a short in the water heater. The water line was NOT bonded and all of the plumbing fixtures in the house were energized to 120-volts. The owner received a shock in the shower (luckily he was not killed) and we located the problem. The 120-volt water heater was connected with 2-wire romex - no equipment ground. The house was equpped with cast-iron drain pipes which were bonded. It was a real mess.