Neutral to Ground Connection Point ?

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Pizza

Senior Member
Location
Minnesota
Here is what I got....
I got a call to go check connections in a panel and make sure it was safe. This is what I found when I got there.... it is a one story office building with five tenant spaces. Originally there was a meter socket enclosure with a panel nippled off of in each space. They ended up eliminating the meter at each space and installed switch gear on the back of the building with the meters in it.

Here is how they eliminated the meter socket enclose... They pulled the meter out. The poco or someone else slugged the three hot wires and left the neutral lugs the way they were. And put a blank cover over it, with the meter socket guts still obviously in.
So then I realized that the neutral lug/s are still bonded to the meter enclosure, which is bonded to the 1 1/2'' EMT that runs about a 100' back to the switch gear.

My questions are
1) Is this Legal? ( I'm pretty sure its not)
2) With the neutral being bonded to the old meter enclose and the EMT, and the building steel... Would there be any return current traveling on that 1 1/2'' EMT? Just a little bit even? Or would all the current be traveling on the just the neutral wire? Could not get my clamp on around it.

Thanks.
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
If you are saying that the Grounded conductor is connected to ground at the original meter sockets and then again and the switch gear then yes I believe this is a serious issue. You will have current flowing back on the EMT.
I believe this is a violation of 250.6(A)
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
Yes current will be flowing on the EMT. This is a fire hazard due to inductive heating of the metal EMT and should be corrected. The N/G bonding should only take place in the switch gear.
 

Pizza

Senior Member
Location
Minnesota
And there was a small fire. It happened at the connector, connecting the nipple between the two panels. There was another electrician that had been called out a few weeks earlier to look at and fix the problem. I'm thinking he just tightened a loose neural at the meter enclosure and pulled new wire. I was called out for a second opinion. I'm thinking there was a loose neutral there and since the neutral was bonded to the old meter enclosure, the return current was finding ground through the emt. <br>Here is a pic, and yes the other electrician left the burnt connector.
 

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don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
The code permits the neutral to be used for all bonding and grounding on the line side of the service disconnect. As to 250.6, "objectional" is defined by the user. Yes there will be current on the metal conduit system and it will divide based on the impedance of the conduit system and the neutral itself. If there is a poor connection in the conduit path there will be much less current on the conduit. There can be problems with excessive heat at conduit connections and a shock hazard on the conduit only if there is a problem with the neutral conductor.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Yes current will be flowing on the EMT. This is a fire hazard due to inductive heating of the metal EMT and should be corrected. The N/G bonding should only take place in the switch gear.
It is not a code violation and not problem unless there is a problem with the grounded conductor. If there is a problem with the grounded conductor there will be more current flowing on the conduit and there could be a heating problem. It would not be an "inductive heating" problem, it would be a resistive heating problem.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
<br><br>Inside. Then pops out the back of the building to the gear at the center of the building.<br><br>
Where are the service disconnects? Conduit inside the building on the line side of the service disconnect would be a violation of 230.70(A)(1).
 

Pizza

Senior Member
Location
Minnesota
The picture vs. what I thought was described in the OP are not making sense to me. Are the conductors coming into the top of that meter base service conductors?

The conductors coming into the top of the meter base are coming from the switch gear at the back of the building about 100' away. The meter and the main breaker are at the switch gear.
 

Pizza

Senior Member
Location
Minnesota
Where are the service disconnects? Conduit inside the building on the line side of the service disconnect would be a violation of 230.70(A)(1).

On the back of the building. the conduit that comes in the top of the meter base runs inside the building for about 100', then pops out to the switch gear. The switch gear has the meter and the main breaker in it for the panel.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
The code permits the neutral to be used for all bonding and grounding on the line side of the service disconnect.
It is not a code violation ...

Sounds to me like the old meter base is now on the load side of the service disconnect. So it would be code violation now.

Where are the service disconnects? Conduit inside the building on the line side of the service disconnect would be a violation of 230.70(A)(1).

Maybe that's why the meters were moved from inside the building to outside the building with new switchgear.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
<br><br>Inside. Then pops out the back of the building to the gear at the center of the building.<br><br>

Yep, you have some objectional current on the EMT going back to the main.

Here's what I don't get. If the objectional current is on the EMT going back to the main, why did the heating/burning appear on the conduit going to the panel? Is there a path from the panel back to the main through the building steel that is lower impedance than the conduit going to the main?

If you ask me, the burning seems more likely the result of a ground fault on the panel side than of a loose neutral connection in the old meter base or the new service.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I am still not clear on the arrangement of this system. If the bypassed meters are on the load side of the service disconnect, then this is a code violation as the bonding of the grounded conductor and the grounding conductor is not permitted on the load side of the service disconnect. My previous comments were based on the bypassed meter being on the line side of the service disconnect.
 

kwired

Electron manager
Location
NE Nebraska
Here's what I don't get. If the objectional current is on the EMT going back to the main, why did the heating/burning appear on the conduit going to the panel? Is there a path from the panel back to the main through the building steel that is lower impedance than the conduit going to the main?

If you ask me, the burning seems more likely the result of a ground fault on the panel side than of a loose neutral connection in the old meter base or the new service.

Maybe there is no building steel. This is now a feeder and not a service so the bond to any grounding electrodes is supposed to be at the service or separately derived disconnecting means. The problem is the neutral is still bonded to the meter can. If the neutral is lost, all the equipment grounding conductors become potential neutral paths. The nipple between the panel and meter as shown may very well be attempting to carry 100% of neutral current. If it is not a good bond between fittings and cabinets that will be place of resistance. Why would it not fail like it did if that happens? If you come at the right time it may be glowing red hot.

Bottom line is installation may have had code violations to start with, moving the meters may have been an attempt to change that, but after that was done there were still violations.

POCO may have wanted meters moved to a location that was more accessible to them and had nothing to do with whether there was a code violation or not, but when all was done code violations were left in the installation.
 

Pizza

Senior Member
Location
Minnesota
Maybe there is no building steel. This is now a feeder and not a service so the bond to any grounding electrodes is supposed to be at the service or separately derived disconnecting means. The problem is the neutral is still bonded to the meter can. If the neutral is lost, all the equipment grounding conductors become potential neutral paths. The nipple between the panel and meter as shown may very well be attempting to carry 100% of neutral current. If it is not a good bond between fittings and cabinets that will be place of resistance. Why would it not fail like it did if that happens? If you come at the right time it may be glowing red hot.

Bottom line is installation may have had code violations to start with, moving the meters may have been an attempt to change that, but after that was done there were still violations.

POCO may have wanted meters moved to a location that was more accessible to them and had nothing to do with whether there was a code violation or not, but when all was done code violations were left in the installation.

This is pretty much what I was thinking. I think that there was a loose connection at that neutral lug in the old meter base. I was told a previous electrician was in there and fixed the problem, but I don't know exactly what they did. They obviously did not un bond the neutral to the old meter base. The wires from the meter base to the panel looked brand new. So maybe he tightened the neutral. If the neutral was loose , then the return current would be on the emt since its bonded to the neutral. And if the locknuts on the emt were not tight, it was arcing a little bit and caused that small fire. Just my guess.
 
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