230.95 Ground Fault Protection Reqd?

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jclint07

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Good morning to all. Here's my question...

1600 Amp, 480/277Y, 3 phase service equipment consist of a main distribution panel with 6 seperate disconnects for subpanels, etc. Since there is NOT an actual main disconnect for this service, then Ground Fault protection is not required. But if there were a a 1600Amp main disconnect, then GFP would be required. Am I reading 250.95 correctly?
 
jclint07 said:
Good morning to all. Here's my question...

1600 Amp, 480/277Y, 3 phase service equipment consist of a main distribution panel with 6 seperate disconnects for subpanels, etc. Since there is NOT an actual main disconnect for this service, then Ground Fault protection is not required. But if there were a a 1600Amp main disconnect, then GFP would be required. Am I reading 250.95 correctly?
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I believe you are correct, as long as none of your 6 disconnects are 1000A or more, since they are technically service disconnects.
 
Thanks for the confirmation. So then would that same rule apply to a 1600 amp, 480/277Y, 3 phase back up generator with an integral 1600 amp breaker, which supplied back up power to an entire tenant space?
 
jclint07 said:
Thanks for the confirmation. So then would that same rule apply to a 1600 amp, 480/277Y, 3 phase back up generator with an integral 1600 amp breaker, which supplied back up power to an entire tenant space?
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No.

The supply conductors are feeders and subject to:

215.10 Ground-Fault Protection of Equipment. Each
feeder disconnect rated 1000 amperes or more and installed
on solidly grounded wye electrical systems of more than
150 volts to ground, but not exceeding 600 volts phase-tophase,
shall be provided with ground-fault protection of
equipment in accordance with the provisions of 230.95.
 
I agree with Smart$,

Since the generator is equipped with a 1600 amp breaker it must be provided with Ground fault protection of equipment in accordance with 215.10.

Chris
 
Thanks Smart. So even though a backup power supply (whether it be considered emergency, legally required or optional) supplies backup power to the entire service, the backup power supply conductors are still treated as feeder conductors and not service conductors? Why would they not be treated as service conductors?
 
jclint07 said:
Thanks Smart. So even though a backup power supply (whether it be considered emergency, legally required or optional) supplies backup power to the entire service, the backup power supply conductors are still treated as feeder conductors and not service conductors? Why would they not be treated as service conductors?
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Because they don't meet the definition of service conductors located in Article 100.

"Service Conductors. The conductors from the service point to the service disconnecting means."

The service point is defined as;

"The point of connection between the facilities of the serving utility and the premise wiring."

Since the generator is not a utility it is not a service point.

Chris
 
raider1 said:
I agree with Smart$,

Since the generator is equipped with a 1600 amp breaker it must be provided with Ground fault protection of equipment in accordance with 215.10.

Chris
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From article 700, I think generator is not permitted to have ground fault protection but it is okay to have ground fault indicator.
 
anbm said:
From article 700, I think generator is not permitted to have ground fault protection but it is okay to have ground fault indicator.
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Unless you have a high impedance grounding system or an ungrounded system how much more indication do you need? A big arc flash is a pretty good indicator, but an indicator will not limit anything which is what GFP is about.
 
anbm said:
From article 700, I think generator is not permitted to have ground fault protection but it is okay to have ground fault indicator.
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Not quite correct.

First, the generator has to provide [legally-required] emergency power. Then it is "not required" to have GFP with auto disconnect [700.26]. Not the same as not permitted.
 
1600Amp back up generator is being installed as "legally required" backup system, so section 701.17 applies. No GFP of equipment required, which I assume pertains to the backup generator's 1600 amp disconnect/ overcurrent protection device.
 
Smart $ said:
Not quite correct.

First, the generator has to provide [legally-required] emergency power. Then it is "not required" to have GFP with auto disconnect [700.26]. Not the same as not permitted.
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True, but in most cases, it would make it very difficult to meet the selective corridination requirements.
 
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