Ok so I Have been discussing the topic of feeder wire size with some of my Co-workers And we can not all agree on the answer.What is the correct size
Aluminum feeder for a 208v 200A 3-p 4-wire Panel no more than 160'
in length in a commercial Building.
Assuming your load does not exceed 180 Amperes, you would be permitted to use 4/0 AWG AL conductors (not considering voltage drop).
Table 310.16 and 240.4(B)
Bryan P. Holland, MCP
So if my load is calculated at 145A, and my distance is 160 Ft, is 4/0 OK ?
At what length does voltage drop come in Play?
Also the terminations in a panel are rated for 75 Degrees,
do I have to run a wire rated for 75 degrees ? or is wire rated for 90 degrees OK??????????
Yes, 90degree wire is just fine
So the feeders are protected at 200A?
Originally Posted by B-Mike
I would think that 110.14(C)(1)(b) would come into play.
Are there any terminals that are rated for 90 degrees?
Is'nt the 90 degree column just for derating?
My answer is 250KCMIL.
Originally Posted by Gogreen100
That would work also, although Bryan gave the correct answer for the minimum size feeder which is #4/0 Al, (75 degrees C, @ 180 amps). 240.4(B) allows you to go up to the next standard OCPD which is 200 amps.
Voltage drop for 145 amps and 160' would be about 1.8% which is fine. You can check that here:
Its fun to calculate, but you will usually find that you dont need to compensate for voltage drop until you get into the 300' range.
Originally Posted by infinity
The only thing is that the breaker that is feeding the wire is 200A.
is 4/0 aluminum OK ?????? ,
ore do i have to use 250 Mcm aluminum ???????
4/0 is okay as has been stated above. There isn't a 180 amp breaker so you can go up to the next size breaker as long as your load does not exceed 180 amps.