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House configuration: 1950s California ranch style single story with attic. Late 1960s split bus panel with probably 100A service. 120V outlets in house are ungrounded 2-prong. Gas enters house adjacent to electrical panel. Underground copper water service enters house around on other side, near hot water heater.

Grounding electrode system: 3x 8' copper clad rods driven into earth and linked by 4 gauge bare copper wire continuing to panel. This grounding system is currently NOT bonded to the nearby gas entry to the house. Once entering wall, the black steel gas pipe runs up and across the attic before descending to gas water heater. At that gas water heater, the gas pipe and adjacent copper cold and hot water pipes are bonded to each other with large bare copper wire (4 or 6 gauge), but not to anything else.

Question: Would bonding the gas pipe at its entry to house to the grounding electrode conductor nearby electrically join the grounding electrodes/conductor, the black steel in-house above-ground gas piping, and the copper water pipes into a single grounding system?

  1. Clearly, the grounding electrodes and conductor ARE part of the system.
  2. The 2020 Minnesota EC 250.50 (I couldn't find the general US one) states:

All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system.

(A)(1) reads:

(1) Metal Underground Water Pipe A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductor(s) or jumper(s), if installed.

Our water pipe is in direct contact with the earth for probably 20 feet underground from the house to the streetside meter. It is bonded to the black steel gas pipe. Shouldn't the black steel gas pipe serve to make it "electrically continuous" to a bonding jumper from the gas pipe entry to the grounding electrode conductor?

Edit: As prompted by the excellent comment of mannaseh... it was code section 250.130(C) of the 2020 Minnesota NEC that prompted my thought:

(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions

The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:

(1) Any accessible point on the grounding electrode system as described in 250.50

(2) Any accessible point on the grounding electrode conductor

(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates

(4) An equipment grounding conductor that is part of another branch circuit that originates from the enclosure where the branch circuit for the receptacle or branch circuit originates

(5) For grounded systems, the grounded service conductor within the service equipment enclosure

(6) For ungrounded systems, the grounding terminal bar within the service equipment enclosure

To me, it seems (C)(1) applies, as the 250.50 description of the grounding system includes all of the possible electrodes when bonded together.

Note: I am not trying to use underground gas pipe as a grounding electrode, but rather the above-ground in-house black steel gas piping to electrically connect our main grounding electrodes and conductor with the copper water pipe system on the other side of the house. As there is currently no electrical ground running to the finished/water pipe containing 2/3 of the house, it would be very convenient to begin incremental addition of grounds to outlets by bonding to nearby copper water pipe before eventually connecting a "real" ground from the other side of the house.

Results edit: It seems clear that no matter the physical properties of the gas pipe, it is not an approved wiring method, and so I will just have to run a bond to the gas pipe by its entry for its own reason, and run a proper ground out to the currently ungrounded house outlets. I very much appreciate the comments and discussion here.

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  • I'm no code expert and can't quote the specifics. But I am pretty sure that while there are all kinds of details relating to when/where/how you connect from "somewhere" to water and gas, the primary grounding to receptacles and appliances has to be back to the panel - i.e., copper wires, not via water or gas pipe. Remember that one of the purposes for ground is "hot shorts to metal case which is connected to ground and completes a circuit that overloads and trips a breaker" - going indirectly via gas/water piping doesn't provide the same conductivity as a copper wire back to the panel. Commented May 13, 2022 at 2:56
  • @manassehkatz-Moving2Codidact Excellent point - I added the code section that motivated my thoughts. It looks like steel is roughly 15x less conductive than copper, but steel pipe would have a much large conductor cross section than e.g. 12 gauge wire, so the gas pipe may actually end up being a better conductor than a copper wire.
    – Armand
    Commented May 13, 2022 at 3:18
  • Ok not sure why you used #4 for ground rods when only #6 is required, the piping is required to be connected to the grounding electrode system within 5’ of entering the building envlope yes it is part of 1 system and yes you can run directly from the electrodes to the gas or water pipes,the gas pipe has no other other connection to the grounding or grounded system. I agree with your reading of the grounding electrode system in code but some here disagree and would down vote a direct quote from the code I know it happened to me. Hope the other info helps.
    – Ed Beal
    Commented May 13, 2022 at 4:02
  • Unless you are doing more work than changing an outlet/switch, then the code that was in place when the last major work was done in what you go by. Up dating a house to newer code is just an option if you feel like it, or are doing/adding work to circuits. Quite sure most 60s and older houses would not pass if they had to be inspected by the most recent code, but do pass with the code in place at the time of building/last major work.
    – crip659
    Commented May 13, 2022 at 11:36

1 Answer 1

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Three 8' ground rods with #4 copper is all the Grounding Electrode you'll ever need for any conceivable residential service. However the run of copper wire must be continuous from the closest rod back to the main panel. It cannot have any splices at all, except for a very limited choice of splice techniques as discussed by Ed Beal in comments below, which require special tools and are not economical for a DIYer).

If you don't have a continuous copper wire run from the ground rods to the panel, then they aren't ground rods at all - they're just wasted material.

While you must bond to gas pipes, you cannot use them in any way whatsoever, no way no how, as any part of your GES. Not even slightly. So bond to them and you're done.

The same applies to the water pipe. Bond to it and you're done.

These two bonds are not to make them part of the GES, they are to protect them from stray voltage.

I don't really care if gas pipe is electrically continuous, there is no way you can use it as any sort of conductor - not an Equipment Grounding Conductor nor a Grounding Electrode. Same applies to water pipe, but the reasons are less boomy.

I think your notion is to run the GEC and the water/gas pipe bonding in one operation by a) making splices to them and b) actually using the pipes themselves as the conductor, even though such pipes are not listed anywhere in Chapter 3 as a valid wiring method. Don't waste your time. You could splice to the GEC as it passes by those pipes, using a split-bolt splice which hangs on the continuous GEC without having a break in it.

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  • I respect your knowledge and experience, and I thought that might be the practical answer, but is there something in the code that says you can't use the aboveground/in house part of the gas piping as an electrical conductor for ground?
    – Armand
    Commented May 13, 2022 at 4:02
  • Alternatively, if I found part of the cold water piping closer to the grounding electrodes and panel, and bonded that to the grounding electrode conductor/panel, could I retrofit grounds for ungrounded outlets to water pipe?
    – Armand
    Commented May 13, 2022 at 4:04
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    Armand yes gas pipe is not allowed to be used as a grounding electrode system but is to be bonded to the system within 5’ of entry. Harper yes you can splice a grounding electrode conductor with compression crimps.
    – Ed Beal
    Commented May 13, 2022 at 4:10
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    @Armand I think you're operating on "wishful thinking" / confirmation bias, your eyes hop right over anything that contradicts what you want to do. You ran right through it. 250.52(B)(1). Also the GEC must be installed as one continuous length without a splice or joint, 250.64(C) so you can't run a wire, splice to a pipe then splice to a wire. Commented May 13, 2022 at 4:15
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    No so much with gas pipes, AFAIK, but one problem with using water piping as a grounding conductor is that in the future, parts of it may be replaced with non-conductive piping, breaking the existing conductor.
    – DoxyLover
    Commented May 13, 2022 at 7:34

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