Sizing of SER cable

[mshields]

I have a friend who is installing a generator (something like 20kW).

FLA's at 240V, 1 phase is 80Amps.

The unit will be outside and he plans on bringing the feeder in via underground PVC piping. Once in the house, he support the SEr cable along the joist until he gets to the panel. What table should I/he use for getting the ampacity of this cable?

 

[Smart $]

I have a friend who is installing a generator (something like 20kW).

FLA's at 240V, 1 phase is 80Amps.

The unit will be outside and he plans on bringing the feeder in via underground PVC piping. Once in the house, he support the SEr cable along the joist until he gets to the panel. What table should I/he use for getting the ampacity of this cable?

Depends on whether the generator will be supplying the whole house load as calculated for the service... and, that is my impression according to most forum participants on this issue. In part, that depends heavily on whether there is an ATS involved. If MTS is involved and not supplying the entire house load as calculated, size per 310.15(B)(16). If ATS or MTS is involved and supplying the entire house load as calculated, size per 310.15(B)(7).

If the gennie has an integral breaker, this fact will also be a consideration in the sizing.

 

[Jljohnson]

You would size your cable/wire from 310.15(B)16 according to the appropriate column for the lowest temperature rating in your system, taking into account all termination lugs, devices, etc. It will likely be the 75 deg. column but may well be the 60 deg. Also, type SER cable can not be used underground per article 338/Uses not permitted.

 

[Dennis Alwon]

Also, type SER cable can not be used underground per article 338/Uses not permitted.

Very good point USE can be outside but not SEU or SER. USE, unless dual rated, cannot be inside. Most USE is dual rated but must be in conduit