Determining if a metal piping system is bonded to ground

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Bro8898

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Birmingham, AL
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Master Plumber
Hey guys. I’ve posted on here a few times before about plumbing and gas piping bonding. I found a way to “test” if a metal piping system is properly bonded to ground. Please let me know if this is an accurate test as well as if I could be missing anything as well as if it presents any safety issues in the “testing” of it.

I take an extension cord and plug it up and take the end of it to a place in the piping system. I put one lead of my meter into the hot and touch the other lead to the piping system (or whatever I’m testing). If the meter reads 120V can I accurately assume the piping system is properly bonded?

Another question: how can I tell if the house wiring system is properly grounded? Will I go outside and look for the presence of ground rods and a properly connected gec? If I don’t see any ground rods how else would I be able to tell? Possibly ook at the water service where the pipe comes in the house? What would indicate that the house is up to the standards of nec 250? And what would not?

Please note that I’m not actually going to do any of these things (other than at my own house). I’m attempting to gain an awareness and understanding of how these systems interact. Your responses have always been very helpful. The more I learn and progress the more questions I have. Thanks in advance
 
For piping systems you may be able to see the pipe clamp. I would use your cord, disconnect GEC/bond, meter ohms from cord ground to end of wire. If you don’t disconnect wire you could be reading connection some where else, ie gas range
 
tom baker said:
For piping systems you may be able to see the pipe clamp. I would use your cord, disconnect GEC/bond, meter ohms from cord ground to end of wire. If you don’t disconnect wire you could be reading connection some where else, ie gas range
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Thanks for your response. I like that. In the gas code book it says that gas piping systems connected to a gas furnace or range are considered to be bonded through the equipment grounding conductor of the circuit serving the appliance. That’s pretty much what I’m wanting to see. Determining that the system is in fact bonded is what is intended. Thanks for the info
 
A typical voltmeter requires so little current that it may read 120v, even though the piping might not be well grounded, due to capacitive coupling to earth.

A solenoid tester uses enough current to energize that it eliminates such "phantom" voltages. A medium-wattage incandescent bulb is another possible test load.

You would be looking for the same thing, whether the piping is grounded well enough to support the current the test load requires, as your meter test attempted to.
 
LarryFine said:
A typical voltmeter requires so little current that it may read 120v, even though the piping might not be well grounded, due to capacitive coupling to earth.

A solenoid tester uses enough current to energize that it eliminates such "phantom" voltages. A medium-wattage incandescent bulb is another possible test load.

You would be looking for the same thing, whether the piping is grounded well enough to support the current the test load requires, as your meter test attempted to.
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That’s good to know. Thanks.
I do have a solenoid tester. I also have a little lightbulb tester that has something that looks like a Christmas tree light inside it and black and red probes. Do you think either of these will work?
 
ptonsparky said:
Look for physical connections. A water pipe clamp. Single conductor leaving the SE. Typically no larger than 4 and bare for the homes I did with cu water lines.
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Single conductor leaving the SE, is that the main electrical panel basically? If I see the large bare wire leaving it that’s attached to the plumbing and or gas piping systems can I assume the electrical wiring system is up to current nec bonding requirements?
 
Bro8898 said:
That’s good to know. Thanks.
I do have a solenoid tester. I also have a little lightbulb tester that has something that looks like a Christmas tree light inside it and black and red probes. Do you think either of these will work?
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The solenoid tester, yes. The other tester, which sounds like a neon-bulb tester, definitely not.
 
Bro8898 said:
I do have a solenoid tester. I also have a little lightbulb tester that has something that looks like a Christmas tree light inside it and black and red probes. Do you think either of these will work?
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Even better and cheaper, a 60W incandescent (NOT LED) light bulb in a rubber pigtail socket like used for temporary lighting. Shove one lead into the hot from your extension cord and touch the other lead to the pipe. If it lights normal brightness you are good.

-Hal
 
hbiss said:
Even better and cheaper, a 60W incandescent (NOT LED) light bulb in a rubber pigtail socket like used for temporary lighting. Shove one lead into the hot from your extension cord and touch the other lead to the pipe. If it lights normal brightness you are good.

-Hal
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I have used that method many times however I spliced an old two wire cord cap on to it.
 
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