NEC Ground Fault Protection of Equipment (GFPE)

[timm333]

I am trying to figure out the ground fault protection of equipment (GFPE) at service entrance as required by NEC 230.95. The utility incoming supply is 34.5kV for an industrial plant, 34.5kV is reduced by transformer to 480V/277V, which then feeds to a 480V/277V switchboard. The secondary breaker of the transformer also acts as the main breaker of the switchboard. Even though the main breaker of the switchboard supplies power to the whole plant, it is not service entrance because service entrance is at 34.5kV. Is GFPE required in this case for the main breaker of switchboard?

Also the exception of NEC 230.95 states that GFPE is not required for continuous process industrial plants where disconnecting the supply would create additional hazards. What kind of industrial plants are those for which the disconnection of the supply will introduce additional hazards? Thanks

 

[kwired]

Still similar requirements in 215.10 for feeders as in 230.95 for services for GFPE.

In places where disconnecting supply would create additional hazards you are more likely to see either ungrounded or impedance grounded systems where you would not be required to use GFPE anyway.

 

[timm333]

Is this GFPE (required by 230.95 and 215.10) designated as 50G or 51G?

 

[timm333]

Can the G (ground) function of LSIG circuit breaker be used to fulfil the requirement of NEC 230.95 and 215.10?

 

[petersonra]

Is this GFPE (required by 230.95 and 215.10) designated as 50G or 51G?

50G is instantaneous and 51G is time delay.

The code allows for up to a 1 second delay in operation so it would appear either is acceptable.

 

[jim dungar]

Can the G (ground) function of LSIG circuit breaker be used to fulfil the requirement of NEC 230.95 and 215.10?

Yes.