Aluminum cabling to a subpanel 1

[bdn2004]

I was planning to run 4/C #4 copper but just found out it costs $5 a foot. Geez. I know to stay away from the #12 and #10 AWG but at what point is it ok to use aluminum conductors?

 

[DRWeig]

Check with your local building authority. In my county aluminum is allowed only for 350 MCM and above. Your location may be different.

Good on ya,

Goober Dave

 

[7anoter4]

According to Southwire [see:

http://www.southwire.com/ordering/PriceSheetIndex.htm

]:
The price of 4 awg building wire type USE of copper stranded conductor will be 5.91 $/ft.
In order to use Aluminum conductor instead of copper you have to go to 1 awg.
The price of 1 awg building wire type USE of aluminum stranded conductor will be 1.4675 $/ft.
Before you choose to go on aluminum see the opinion of Interstates:

http://www.interstates.com/Resource.... Copper Conductors A Serious Alternative.pdf

or

http://www.tpub.com/neets/book4/11e.htm

 

[bdn2004]

This is actually at my house which I'm remodeling and upgrading the service. So its personal to me...it's my money!

I had fully intended to use copper, but since it's going to cost me $1000 for the #4 copper subfeeds alone, not to mention the utility who is charging me for their part (which by the way will be #2/0 AL) - I'm re-thinking my plan.

That is good advice to check AHJ. They sell 4/C #2 AL at Lowes. I don't have the Code here, but I think I can use Table 315.(something) for Services and Feeders to size this 100A wire. This part of the country didn't buy into the arc fault breakers or the tamper proof receptacles so I'm betting AL this size is ok.

 

[redfurry]

I've been looking into something similar in my house!

According to what I've looked at under NEC2008, #2 Al can only be used for a 100A circuit if used for the house service (i.e. from meter to service entry panel/disconnect).

If you're running this wire internally (i.e. to a sub-panel), you're limited to the 60C rating which is 90A.

 

[alehman]

I don't think the NEC prohibits aluminum in any size so long as it's AA-8000 alloy and the terminals are marked for aluminum. Can't use type USE cable inside.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[bdn2004]

Redfurry,

Unfortunately I don't have a NEC here with me...but I question your call here. There is a chart in the Code I believe its 315.something. It's strictly for residential service entrance and feeders. This chart allows smaller sizes to be used, but again only in a house. nd if a feed to a subpanel isn't considered a feeder then what is?

Also, why can't you use the exception to the general rule..that allows you to bump to the next size breaker when the cable ampacity doesn't correspond to a standard size (240.3 & 240.6 I think...)? Again, no Code handy, but 90A doesn't sound like a standard size and that rule would apply.