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My situation is that I have a house built in about 1920. The in-home plumbing is mostly 1/2" copper pipe from the basement water meter to the water taps. I had a large local plumbing company install a new whole-house filter system near the water meter recently (in 2024). The filter and some of the new piping are plastic. Because the plumber cut the copper pipe I am concerned about the possibility that old equipment somewhere in the house might have been "grounded" to the copper water pipe in the past. If so, and if there is electrical leakage due to an electrical fault, there might be an electrical potential between the portion of copper pipe leading to the street, and the portion serving the house. It is possible for a person easily to touch both portions of the copper piping simultaneously while standing on the concrete floor. I know enough about electricity to understand that for personal safety I should bond the two portions of copper piping to assure that they are at equal electrical potential. I have decided to purchase grounding clamps and heavy-gauge copper wire and install them to assure future equipotentiality of the two portions of copper piping. I know how to do the work and remain safe (measure the voltage between the two copper pipes, and turn off power at the main circuit breakers). My question is one of curiosity: does the National Electrical Code require such a bond in an old house, and if so, what is the applicable citation, including the version number or year of publication?

Clifford Chamney
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I had the same scenario when I added a whole house water filter system. The instructions specifically stated that if the piping that was cut to enable the install was metal, then a wire bridge must be completed to continue bonding both ends of the piping. ( Sorry don't have the original document)

It may be code. Maybe not. However it is easily done and with little cost.

I used 2 bronze water pipe grounding clamps and a length of #6 wire. Or you could just purchase a Grounding kit..

Better safe than sorry.

RMDman
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