Sub-panel

[ICE]

The situation: A service panel upgrade to 225 amps rated bus is being installed at the opposite end of the house from the existing panel. The existing thirty year old 100 amp meter main panel will be converted into a sub-panel. There is no label on the existing panel. There is no indication as to the maker of the intended sub-panel.

Question: Do you allow the existing panel to be modified to isolate the neutral? Sorry, no pictures.

 

[steveray]

They would just add an EGC bar to the enclosure with the proper machine screw and pull the green screw, no?...Shirley that wouldn't violate the listing of any panel?

 

[wwhitney]

Seems like there are two questions:

1) Is there a compliant way to bypass the meter socket in the old meter main to supply the panelboard portion of the equipment?

2) Is the old meter main rated "Suitable Only For Use As Service Equipment"? That would mean that its neutral bar is permanently bonded to the case and would preclude its reuse as a subpanel.

Cheers, Wayne

 

[steveray]

Missed the "meter main panel" part....Don't know how they are to "modify", but Wayne sounds like he does...

 

[BN4537]

The situation: A service panel upgrade to 225 amps rated bus is being installed at the opposite end of the house from the existing panel. The existing thirty year old 100 amp meter main panel will be converted into a sub-panel. There is no label on the existing panel. There is no indication as to the maker of the intended sub-panel.

Question: Do you allow the existing panel to be modified to isolate the neutral? Sorry, no pictures.

I think the short answer is that you will be violating the listing of the 30 year old panel, therefore it is a violation. If the contractor can't find the listing info, they really can't dispute that claim.

But... I could be convinced by a savvy electrician who had a good plan to isolate the neutral from the case. There are safe and robust ways to accomplish this. I could be convinced to make a deal on a case-by-case basis to accommodate as-built conditions.

NSi Industries 2/0-14 AWG, 7 Circuit Aluminum Isolated Ground Bar- 1 Count GBA20-7 - The Home Depot

This isolated ground bar has 7 tapping circuits that accept a range of copper cable sizes from #2/0 AWG to #14 AWG and handles up to 600V. The 2.88 in. long bar is made of aluminum and has straight-slot

www.homedepot.com

 

[ICE]

Seems like there are two questions:

1) Is there a compliant way to bypass the meter socket in the old meter main to supply the panelboard portion of the equipment?

2) Is the old meter main rated "Suitable Only For Use As Service Equipment"? That would mean that its neutral bar is permanently bonded to the case and would preclude its reuse as a subpanel.

Cheers, Wayne

The hardware above the bus is to be removed. There is no label.

 

[jar546]

Main panels are converted to sub-feeds with separated neutrals and grounds all the time. A few years ago I added an ATS to a 1200A 480v service and then had to convert the 1968 Frank Henry switch gear to a sub-feed. You are making a once service-rated panel no longer needed to be service-rated. Why are we making a mountain out of a mole hill?

 

[wwhitney]

Main panels are converted to sub-feeds with separated neutrals and grounds all the time. A few years ago I added an ATS to a 1200A 480v service and then had to convert the 1968 Frank Henry switch gear to a sub-feed. You are making a once service-rated panel no longer needed to be service-rated. Why are we making a mountain out of a mole hill?

Being a meter main complicates the situation.

Easy case: the meter main used regular conductors to supply its main breaker from the meter section, and the neutral bar can be isolated from the case by removing a bonding jumper or bonding screw, and there is adequate space for adding an equipment grounding bar.

Hard case: the meter main used bus bars to supply its main breaker from the meter section, so now you need to figure out how to land the feeder conductors to supply panelboard. And the neutral bar is permanently bonded to the case, meaning the equipment was labeled "Suitable Only For Use As Service Equipment." You have to be willing to ignore that (now missing) label, and add an isolated neutral bar as suggested in post #5, and hope there is a location for it where it will have adequate wire bending space. And the meter main is flush-mount in stucco, so changing out the equipment is difficult.

Cheers, Wayne

 

[jar546]

Being a meter main complicates the situation.

Easy case: the meter main used regular conductors to supply its main breaker from the meter section, and the neutral bar can be isolated from the case by removing a bonding jumper or bonding screw, and there is adequate space for adding an equipment grounding bar.

Hard case: the meter main used bus bars to supply its main breaker from the meter section, so now you need to figure out how to land the feeder conductors to supply panelboard. And the neutral bar is permanently bonded to the case, meaning the equipment was labeled "Suitable Only For Use As Service Equipment." You have to be willing to ignore that (now missing) label, and add an isolated neutral bar as suggested in post #5, and hope there is a location for it where it will have adequate wire bending space. And the meter main is flush-mount in stucco, so changing out the equipment is difficult.

Cheers, Wayne

Agree, meter mains are a whole different animal and I can't really think of any situation where they would need to be converted to a sub since they are, in fact the service disconnect and meter inside the same enclosure.

 

[wwhitney]

Agree, meter mains are a whole different animal and I can't really think of any situation where they would need to be converted to a sub

But that is what the OP is about, so let's stay on topic.

Two simple examples of how this might occur: you want to upgrade the service from 100A to 200A, or you have an addition that would cause the existing service drop to be too close to the new roof or new windows, so you need to move the service equipment location.

Cheers, Wayne