2 hour rated generator feeder

[mshields]

NFPA 99 2015 version calls for the Life Safety branch to go by Article 700 but with certain exceptions, among them modifications to 700.10 rendering rated feeders unnecessary.

This has not yet been adopted in MA although I believe it will be when our new building code based on the 2015IBC comes out later this year.

So Critical branch feeders no longer require 1 or 2 hour rating per the 2014 NEC when they were deemed no longer Emergency", Soon Life Safety won't require their feeders to be rated, my question is where does this leave the feeder from the generator to the Essential Electrical System main switchboard or branch disconnects. Normally, we would have this rated for 2 hours from the point it enters the building.

It boils down to whether or not the generator feeder's rating is governed by what the worst case of the three EES branches require OR is there a separate requirement governing this feeder and if there is, does it require 1 or 2 hour rating?

Thanks,

Mike

 

[xformer]

NFPA 99 2015 version calls for the Life Safety branch to go by Article 700 but with certain exceptions, among them modifications to 700.10 rendering rated feeders unnecessary.

This has not yet been adopted in MA although I believe it will be when our new building code based on the 2015IBC comes out later this year.

So Critical branch feeders no longer require 1 or 2 hour rating per the 2014 NEC when they were deemed no longer Emergency", Soon Life Safety won't require their feeders to be rated, my question is where does this leave the feeder from the generator to the Essential Electrical System main switchboard or branch disconnects. Normally, we would have this rated for 2 hours from the point it enters the building.

It boils down to whether or not the generator feeder's rating is governed by what the worst case of the three EES branches require OR is there a separate requirement governing this feeder and if there is, does it require 1 or 2 hour rating?

Thanks,

Mike

Last time I checked Feeder Conductors don't have an hour rating. But Article 701 Does say that the generator must have a 2 hour fuel supply for the legally required system.

 

[GoldDigger]

It boils down to whether or not the generator feeder's rating is governed by what the worst case of the three EES branches require OR is there a separate requirement governing this feeder and if there is, does it require 1 or 2 hour rating?

Thanks,

Mike

From what I think I remember, emergency or critical load circuits have to be carried independently all the way back to the generator so that they have their own OCPD/main disconnect.
In that case the whole question of how to rate a combined feeder does not even arise.

Although I suppose that if there is no OCPD at the generator at all, and you get that to pass, you could have a combined feeder???