Ground Fault Protection

Status
Not open for further replies.
M

Mike373

Member
Location
California
If the service for a building has a 2000 amp, 277/480 volt 3-phase GFI protected main breaker installed, will a 2000 amp, 277/480 volt meter main that is downstream also need to have GFI protection? I am not sure why you would install redundant GFI protection, but that is what an engineer is insisting on. Any code references would be much appreciated.

Thank you,

Mike
 
P

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Mike373 said:
If the service for a building has a 2000 amp, 277/480 volt 3-phase GFI protected main breaker installed, will a 2000 amp, 277/480 volt meter main that is downstream also need to have GFI protection? I am not sure why you would install redundant GFI protection, but that is what an engineer is insisting on. Any code references would be much appreciated.

Thank you,

Mike
Click to expand...

He might want to set the downstream CB GF trip at a lower setting so it trips first so the upstream one doesn't trip on a GF. Whether this would actually work in a GF situation seems a bit dubious to me.

I don't think there is any code that requires you to put it there.
 
rbalex

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Mike373 said:
If the service for a building has a 2000 amp, 277/480 volt 3-phase GFI protected main breaker installed, will a 2000 amp, 277/480 volt meter main that is downstream also need to have GFI protection? I am not sure why you would install redundant GFI protection, but that is what an engineer is insisting on. Any code references would be much appreciated.

Thank you,

Mike
Click to expand...
I just finished a review for another engineer’s design. He insisted what he had done was a utility company’s requirement. I knew it wasn’t. However, I made it very clear to both my client and the other engineer that it was his design and he had the right to accept or reject my comments – without any justification to me.

Unless you have a contact for design responsibility AND the engineer has a stipulation in his contract for you to “value engineer” his design - stay out of it or, in California, he can have you cited for practicing engineering without a license. [EDIT ADD:] There's no reason for anyone else to speculate on the design either.
 
Last edited:
J

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Mike373 said:
If the service for a building has a 2000 amp, 277/480 volt 3-phase GFI protected main breaker installed, will a 2000 amp, 277/480 volt meter main that is downstream also need to have GFI protection? I am not sure why you would install redundant GFI protection, but that is what an engineer is insisting on. Any code references would be much appreciated.
Click to expand...

You have used the word "main" twice.

There is only one service "entrance" per service drop, except when you have multi-metering. Service entrance equipment is subject to the GF requirements in 230.95. Non service entrance equipment would be subject to the GF requirements in 215.10, which does contain an exception to putting two GFs in series. Emergency and hospital systems have additional GF requirements and exceptions.

Have you discussed this with the engineer of record?
 
M

Mike373

Member
Location
California
Ok Jim, I just want to make sure I understand. This is a multi-meter application, but the service entrance will only be the main breaker (main disconnect for the whole building) which will need to be GFPE, right?

The breaker that is downstream of the main disconnect for the building should not be GFPE protected under Exception no. 2: The provisions of this section shall not apply if ground-fault protection of equipment is provided on the supply side of the feeder and on the load side of any transformer supplying the feeder.
May be part of the confusion, there are (2) 2000 amp breakers, one at the service entrance, and one on the tenant side of the meter in a multi-metered service. The second meter is a small house panel.

Thank you all for your time, I just want to understand.
 
Status
Not open for further replies.
Top