Objectionable current on gas main

garbo said:
As long as Ultility companies only supply one high voltage lead to thier thousands of distribution transformers this will be a potential problem.
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don_resqcapt19 said:
That would be a singe wire earth return and is never used in populated areas. The utility uses a common conductor as the neutral for both their high voltage distribution and the secondary of the transformers that supply power to their customers.
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I would not say that is necessarily a SWER. It seems perfectly reasonable to refer to a transformer fed L-N from an MGN to have "only one high voltage lead"
 
don_resqcapt19 said:
That would be a singe wire earth return and is never used in populated areas. The utility uses a common conductor as the neutral for both their high voltage distribution and the secondary of the transformers that supply power to their customers.
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Well here in Philadelphia, the 6th most populated city, PECO had been cutting corners by only supplying one high voltage conductor to every transformer that I ever observed in last 60 years. They never connect the common center tap ( one from primary of transformer and the other to the center tap of the 120/240 volt secondary ) to any other upstream source like a poster stated months ago.
 
garbo said:
. They never connect the common center tap ( one from primary of transformer and the other to the center tap of the 120/240 volt secondary ) to any other upstream source like a poster stated months ago.
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Typically on a single bushing transformer, the other side of the MV winding is connected internally to the tank. I don't think I've ever seen one where it's connected internally to the secondary center tap. There will be a lug on the tank somewhere that the MGN lands on.
 
Well thought I'd post an update my boss went over there with the building super and killed all the breakers to all units and the current dropped to zero on the gas pipe.
 
pipe_bender said:
Well thought I'd post an update my boss went over there with the building super and killed all the breakers to all units and the current dropped to zero on the gas pipe.
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Which just shows that there's one or more parallel paths created by at least two neutral-gas bonds in the building. (And that this talk about whether utilities ground a primary conductor is off topic.)
 
electrofelon said:
I would not say that is necessarily a SWER. It seems perfectly reasonable to refer to a transformer fed L-N from an MGN to have "only one high voltage lead"
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Ok, that is not how I read that. Most of the distribution transformers in my area are line to neutral.
 
jaggedben said:
Old appliances with bare neutral conductors that bond frames are only allowed to be connected to service panels, i.e. the meter pack in this case, not subpanels in the units.
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So it seems the 2023 NEC may have overlooked this case as 2023 NEC 250.140 (B) appears to allow a 3-wire connection to remain when a service is converted to a sub panel. I am not too familiar with CSST gas pipe and how its bonded, but it does seem like there is a parallel neutral path for the entire feeder if 250.140(B) in the 2023 NEC is used with a gas / electric range or a range with a connection to a metal water pipe such as a "pot filler".
 
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garbo said:
Well here in Philadelphia, the 6th most populated city, PECO had been cutting corners by only supplying one high voltage conductor to every transformer that I ever observed in last 60 years. They never connect the common center tap ( one from primary of transformer and the other to the center tap of the 120/240 volt secondary ) to any other upstream source like a poster stated months ago.
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In many cases the connection between the primary neutral and the secondary neutral is inside the transformer.
 
Seems like you should have no measurable current on a gas pipe, perhaps a few mA but anything in the level of amps seems wrong?
 
Hey I thought I would update this, it turns out the apartments do have 3-wire range plugs and combo / gas electric ranges. Unplugging all the 3-wire combo gas / electric ranges got rid of the current on the gas main.
There is some ongoing debate as to how to solve this and if its really an issue.
 
LarryFine said:
You (or possibly a neighbor) have service neutral issues.
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My they did have the utility out to check, they used what looked like a box of hair dryers and as a test said their neutral is fine, but you never know, as I have herd that before and then a few days later another building goes out and woops it was them.
It does seem like the 3-wire range outlets should be upgraded to 4-wire but the building owner is broke and does not want to do anything more than code requires.
 
pipe_bender said:
My they did have the utility out to check, they used what looked like a box of hair dryers and as a test said their neutral is fine, but you never know, as I have herd that before and then a few days later another building goes out and woops it was them.
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Years ago, a customer had open-neutral syndrome, and the POCO swore I was wrong . . . until I told them to go back back and test it with the main breaker on. :rolleyes:

They repaired the underground break (aluminum oxide about 2' long) the same day.

pipe_bender said:
It does seem like the 3-wire range outlets should be upgraded to 4-wire but the building owner is broke and does not want to do anything more than code requires.
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If the entire pathway, from appliance terminals to panel, is intact, it's no less safe than a service.
 
pipe_bender said:
My they did have the utility out to check, they used what looked like a box of hair dryers and as a test said their neutral is fine, but you never know, as I have herd that before and then a few days later another building goes out and woops it was them.
It does seem like the 3-wire range outlets should be upgraded to 4-wire but the building owner is broke and does not want to do anything more than code requires.
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A bad service neutral may be downstream of the utility equipment.
 
pipe_bender said:
Hey I thought I would update this, it turns out the apartments do have 3-wire range plugs and combo / gas electric ranges. Unplugging all the 3-wire combo gas / electric ranges got rid of the current on the gas main.
There is some ongoing debate as to how to solve this and if its really an issue.
Click to expand...

I don't know why people are jumping to conclusions about bad service neutrals. This description here suggests that each range frame is bonded to its gas pipe and neutral.
And so neutral current from any of those three unit's subpanel can return to the service via gas pipe and the other units' neutrals. (As well as perhaps another gas bond to the grounding electrode system.) Might be hard to provide a proper EGC to each range and unbond the neutrals, but that seems like the proper solution.
 
jaggedben said:
I don't know why people are jumping to conclusions about bad service neutrals. This description here suggests that each range frame is bonded to its gas pipe and neutral.
And so neutral current from any of those three unit's subpanel can return to the service via gas pipe and the other units' neutrals. (As well as perhaps another gas bond to the grounding electrode system.) Might be hard to provide a proper EGC to each range and unbond the neutrals, but that seems like the proper solution.
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I agree sounds like a parallel path through the gas line since the ranges are 3-wire this is not a huge surprise.
 
jaggedben said:
I don't know why people are jumping to conclusions about bad service neutrals. This description here suggests that each range frame is bonded to its gas pipe and neutral.
And so neutral current from any of those three unit's subpanel can return to the service via gas pipe and the other units' neutrals. (As well as perhaps another gas bond to the grounding electrode system.) Might be hard to provide a proper EGC to each range and unbond the neutrals, but that seems like the proper solution.
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Gas range is usually plugged into a typical 5-15 or 5-20 receptacle and neutral and EGC are not bonded.

Electric ranges were once permitted to utilize the branch circuit grounded conductor for equipment grounding - these likely have no connection to gas piping unless maybe there is incidental contact between the appliance and a not in use gas pipe behind it.
 
pipe_bender said:
Hey I thought I would update this, it turns out the apartments do have 3-wire range plugs and combo / gas electric ranges. Unplugging all the 3-wire combo gas / electric ranges got rid of the current on the gas main.
There is some ongoing debate as to how to solve this and if its really an issue.
Click to expand...
Likely It could be related to a fault in one of the ranges. Does just disconnecting only any one of the ranges eliminate the current?
It is an issue that could be a shock hazard. You've confirmed it to be associated to the ranges, so now need to determine if it is just one or all three.
Other question would be are all the gas lines bonded of the six units, or just the three you confirmed as contributing to issue?
kwired said:
Gas range is usually plugged into a typical 5-15 or 5-20 receptacle and neutral and EGC are not bonded.

Electric ranges were once permitted to utilize the branch circuit grounded conductor for equipment grounding - these likely have no connection to gas piping unless maybe there is incidental contact between the appliance and a not in use gas pipe behind it.
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OP has described a dual range usually gas cook top and electric oven. This is usually getting a L/N load for lights and electronics and timers off from one leg of the 240V. If Neutral connection is poor it will be using the frame ground that with a three wire is bonded to the N and will use both for the return neutral.
 
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