Aluminum Feeders

[B-Mike]

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.

[bphgravity]

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)

[B-Mike]

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??????????

[walkerj]

Yes, 90degree wire is just fine

[Gogreen100]

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??????????

So the feeders are protected at 200A?
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.

[infinity]

My answer is 250KCMIL.

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:

http://www.electrician2.com/calculat...culatoradv.htm

[jrannis]

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:

http://www.electrician2.com/calculat...culatoradv.htm

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.

[B-Mike]

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 ???????

[wirebender]

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.

[B-Mike]

Thank you All.