feeder sizing

Status
Not open for further replies.
G

gold coast

Member
Location
California
What size wire for a 200 amp feed to a house approx 300 feet from meter main? 120/240V 400 amp single phase main service. Can you derate the 200 amps at all? I'm thinking how likely is it to actually be drawing a full 200 amps at any one time? In reality even at full operation at any given time what is the actual load going to be? 60 amps, 80 amps, maybe over 100 with a full house on Thanksgiving? This house is approx 4700 sq ft with gas heat and kitchen cooking appliances.
 
ron

ron

Senior Member
Location
New York, 40.7514,-73.9925
Re: feeder sizing

Check Annex D in the code book for a demand load calculation example. Once you figure the load, then go to Table 310.15(B)(6) for the service conductor size.
 
dereckbc

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: feeder sizing

IMHO consider over sizing the feeder. The distance you mention is long, and the house appears to be upscale. Why risk excessive voltage drop? If the house has air conditioning, flickering or dimming lights could be embarrassing.

Assuming the load only reaches 100 amps, 2/0 should be fine. If it were my home, I would use 3/0 or 4/0. Perform some load calculations and decide what to do.

[ March 19, 2003, 11:00 PM: Message edited by: dereckbc ]
 
B

bphgravity

Senior Member
Location
Florida
Re: feeder sizing

I agree with Dereck. Why install the feed with bare minimum capacity. This is a long run and you never know what type of loads may be added later. This is a consideration that you are responsible for per 90.8 of the NEC. You may indeed want to upsize the feeders for these purposes, and definitely do not down size the grounded conductor in any case.

[ March 20, 2003, 09:38 AM: Message edited by: bphgravity ]
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: feeder sizing

bp,
There are no "mandatory rules" in 90.8. The section is infromational only and involves design issues, not code or safety issues.
Don
 
B

bphgravity

Senior Member
Location
Florida
Re: feeder sizing

Thanks Don, I know it is not required, but I do think good design and good workmanship is the responsibility of every electrician whether or not the code requires it.
 
Status
Not open for further replies.
Top