Objectionable current on gas main

jim dungar said:
But is the neutral-ground bond in the box with the receptacle? I always thought agree bonding occurred in the appliance.
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I am unaware of any information on the receptacle. The same thing would happen even if the neutral was not bonded in the box.

From my understanding, the multifamily dwelling has multiple units with a combination gas/electric range where the range is fed from a configuration that does not have a equipment ground. L1 + Neutral or L1 + L2 + Neutral. The frame of the range and the metal gas pipe would be electrically bonded at the range. Since there is no EGC, the neutral is bonded to the frame.

Since the service has a bonding jumper to the gas pipe, there is now a parallel path for neutral current from the range to the service's neutral.

That is more or less what the graphic shows. That is what I believe is happening based on the OPs comments about turning off one unit and still measuring current on the main. I also believe they mentioned that turning the main off meant there was zero current on the gas pipe main.

I think Tortuga was just putting other possible bonds, I think it is from the exception in the 2020.

"
Exception:
For existing branch-circuit installations only where an equipment grounding conductor is not present in the outlet or junction box, the frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be permitted to be connected to the grounded circuit conductor if all the following conditions are met."
 
Thanks everyone for the help, to clarify for those who asked its a 50 Amp 3 wire NEMA 10-50 receptacle that powers the ranges, the ranges have a gas cooktop and electric oven.
It would be quite a job to rewire all the range circuits, and the building owners don't want to spend any money that they don't have to, nor do they want to disrupt the tenants.

One last question I have herd you can run a bare or green ground wire externally and tap off to ground old outlets is this ok to do for a converting a range outlet from a 3 wire to a 4-wire NEMA 14-50?
And this wire is sized for the largest circuit that will be grounded so a #10 bare could do all the ranges?
We'd actually use #8 bare because we have a roll of that.
Thanks again
 
pipe_bender said:
One last question I have herd you can run a bare or green ground wire externally and tap off to ground old outlets is this ok to do for a converting a range outlet from a 3 wire to a 4-wire NEMA 14-50?
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If it is something doable you would need to connect to something with a 10 AWG grounding conductor since it is a 40 or 50 amp branch circuit, and I'd guess most of what is close by and convenient only has 14 or 12 AWG grounding conductors.

Placing dielectric union on gas piping maybe something worth consideration?
 
pipe_bender said:
Thanks everyone for the help, to clarify for those who asked its a 50 Amp 3 wire NEMA 10-50 receptacle that powers the ranges, the ranges have a gas cooktop and electric oven.
It would be quite a job to rewire all the range circuits, and the building owners don't want to spend any money that they don't have to, nor do they want to disrupt the tenants.

One last question I have herd you can run a bare or green ground wire externally and tap off to ground old outlets is this ok to do for a converting a range outlet from a 3 wire to a 4-wire NEMA 14-50?
And this wire is sized for the largest circuit that will be grounded so a #10 bare could do all the ranges?
We'd actually use #8 bare because we have a roll of that.
Thanks again
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Yes, you can do this according to 250.130(C).

I assume you already determined that the receptacles aren't wire with a metal raceway you could use as an EGC.
 
jaggedben said:
Yes, you can do this according to 250.130(C).
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My boss was informed today that the state of Massachusetts has for a long time opted to delete 250.130(C).
Does anyone on here from Mass know why they did that?
kwired said:
Placing dielectric union on gas piping maybe something worth consideration?
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Yeah we asked the pipe fitters to do that, they said its an electrical issue citing the NEC 250.6 for objectionable current.
They actually want another bond wire ran to bond more flex gas pipe that they are installing when the issue is resolved, my boss was saying he has no idea what to run and they can bond their own pipes.
They are saying its state laws require an electrical contractor to install the CSST gas bonding.
 
If I am understanding this correct the neutral current is coming from the entire panel as the old range is a parallel conductor, not just the range.
Is this a 120/208 3 wire panel? I bet it is I always see more neutral current at 208 buildings.
 
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