feeders to single family 310.15(B) (6)

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Riograndeelectric

Senior Member
I am bidding a house. owner wants the main 200A service on the detached Garge and then run form detached garage to house approx 100 feet away.

a according to 310.15(B) (6) since this is a single family and am running fedder from main disconnect to panel board at house I Can use 4/0 Aluminum 4 conductor wire form garage to House.
I am correct on what I ma interpreting?
Thanks.
Cameron
 

kwired

Electron manager
Location
NE Nebraska
I am bidding a house. owner wants the main 200A service on the detached Garge and then run form detached garage to house approx 100 feet away.

a according to 310.15(B) (6) since this is a single family and am running fedder from main disconnect to panel board at house I Can use 4/0 Aluminum 4 conductor wire form garage to House.
I am correct on what I ma interpreting?
Thanks.
Cameron

You are correct, the service conductors to the detached garage however are not allowed to be sized to 310.15(B)(6), although it is possible to still end up being able to use 4/0 aluminum if total load calculation is not over 180 amps.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I guess it depends on whether the AHJ considers the garage as part of the dwelling unit. In some opinions on this site the garage is a detached garage and not part of the dwelling unit so 310.15(B)(6) would apply.
 

Riograndeelectric

Senior Member
You are correct, the service conductors to the detached garage however are not allowed to be sized to 310.15(B)(6), although it is possible to still end up being able to use 4/0 aluminum if total load calculation is not over 180 amps.[/quote


I would have to up size my feeder conductor's going to the house according 310.16.at 75 C 4/0 would be good for 180 amps or use 250MCM AL good for 205A

I had planed on using feed thru lugs on the garage panel to feed the house instead of having to use a 200 main breaker.

I have a call into the inspector to get hi opinion before I bid the job.

Thanks.
Cameron
 

kwired

Electron manager
Location
NE Nebraska
You are correct, the service conductors to the detached garage however are not allowed to be sized to 310.15(B)(6), although it is possible to still end up being able to use 4/0 aluminum if total load calculation is not over 180 amps.[/quote


I would have to up size my feeder conductor's going to the house according 310.16.at 75 C 4/0 would be good for 180 amps or use 250MCM AL good for 205A
The feeder to the house is allowed to be sized to 310.15(B)(6) as long as it supplies the entire load of the dwelling. The service conductors to the garage supplies a dwelling and another structure so 310.15(B)(6) can't be used for this.

If total load on service (at the garage) is 180 amps or less (we are talking about article 220 load calculations not what size breaker you installed)
then 4/0 aluminum is rated for that amount in table 310.16 and you are allowed to use next higher overcurrent device so 200 amps is still alright on 4/0 aluminum.


I had planed on using feed thru lugs on the garage panel to feed the house instead of having to use a 200 main breaker.

Feed thu lugs is inexpensive way to do this and is acceptable.

The house must still have a main disconnect located in or on the house main breaker panel is most common way of doing this.
 
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