Sub-panel

[Oldmaster2]

I see that the 83% percentage conductor size as it applies to feeders serving a sub panel is only viable if the panel serves the entire load.
Regarding a sub panel, how can it not be the entire load? The argument is that the service panel does not carry the entire load because of the sub panel ? My response is the breaker that feeds the sub panel is located in the main service panel, thus the service panel serves the entire load. Maybe I'm just confused?

 

[xformer]

I see that the 83% percentage conductor size as it applies to feeders serving a sub panel is only viable if the panel serves the entire load.
Regarding a sub panel, how can it not be the entire load? The argument is that the service panel does not carry the entire load because of the sub panel ? My response is the breaker that feeds the sub panel is located in the main service panel, thus the service panel serves the entire load. Maybe I'm just confused?

83% for a feeder to a sub panel is not code compliant.

 

[infinity]

You have two panels. The first panel has an OCPD and a feeder to the second panel. The sub-panel is not carrying the entire load if the first panel has other breakers supply other loads.

 

[wwhitney]

83% for a feeder to a sub panel is not code compliant.

Unless (a) the feeder carries the entire load of a dwelling unit (e.g. the service supplies two separate dwelling units) or (b) the feeder is the same size as an upstream feeder than does carry the entire load of a dwelling unit (e.g. a 100A feeder on a 100A service for one dwelling unit).

Cheers, Wayne

 

[infinity]

Oldmaster can you explain the exact installation that you have with all the conductor and OCPD sizes?

 

[Oldmaster2]

100 amp service . 2/2/4 seu .
Feed to sub panel 1/1/2/4 Ser
Inspector insists service entrance conductor is must be #1. Since in his mind it does not carry the full load because of the sub,?

 

[infinity]

100 amp service . 2/2/4 seu .
Feed to sub panel 1/1/2/4 Ser
Inspector insists service entrance conductor is must be #1. Since in his mind it does not carry the full load because of the sub,?

The fact that the sub is fed by #1's is irrelevant. The service conductors to the service panel are properly sized according to the 83% rule because they are carrying the entire load. Not sure why the inspector is missing that. Maybe he needs to see a one line diagram.

 

[don_resqcapt19]

100 amp service . 2/2/4 seu .
Feed to sub panel 1/1/2/4 Ser
Inspector insists service entrance conductor is must be #1. Since in his mind it does not carry the full load because of the sub,?

How do the service entrance conductors not carry the full load?

 

[LarryFine]

100 amp service . 2/2/4 seu .
Feed to sub panel 1/1/2/4 Ser
Inspector insists service entrance conductor is must be #1. Since in his mind it does not carry the full load because of the sub,?

He's wrong, the service conductors DO carry the full load. How could they not?

And your feeder conductors need not be larger than the service conductors.

 

[letgomywago]

Are you phili where they require testing and licensing or outside. If outside is your inspector a "Building" inspector who hasn't received much electrical specialty training?

 

[Oldmaster2]

I told him today I want an appeal.

 

[letgomywago]

I told him today I want an appeal.

Have code ready to go a written down. If your appeal does not go before Electricans but instead to Building officials this may be the first time they have seen the code sections before.

 

[wwhitney]

The same holds true if the first panel has breaker slots even if they are not used.

No, not if the breaker slots are unused. And you might use a breaker for something other than a load, like interconnecting PV or ESS.

Cheers, Wayne

 

[xformer]

Unless (a) the feeder carries the entire load of a dwelling unit (e.g. the service supplies two separate dwelling units) or (b) the feeder is the same size as an upstream feeder than does carry the entire load of a dwelling unit (e.g. a 100A feeder on a 100A service for one dwelling unit).

Cheers, Wayne

Wouldn't your first example be actually two services? One for each structure or separate dwelling unit?

 

[electrofelon]

Wouldn't your first example be actually two services? One for each structure or separate dwelling unit?

Most of the time what looks like multiple services is one service with multiple sets of service entrance conductors per the 230.40 exceptions.