ECN Forum

Cu or Al

Posted By: Wizzie Electric

Cu or Al - 03/06/07 06:34 PM

I am replacing a panel 100A and the SEC is #2 Cu and is too short. The home owner wants to use up a roll of #2 Al he has. Is it acceptable to replace the #2 Cu between the panel and meter with #2 Al. And is the use of an antioxadent not required by the NEC (just wondering)
Posted By: ITO

Re: Cu or Al - 03/06/07 06:54 PM

Depends on:

1) Local codes, some areas may not allow Al.
2) The insulation of the AL conductor (75°C or 90°C)READ T-310.16 for Ampacity. If you cant tell what type of wire it is, you should not use it.
3) If the lugs in the panel and meter are listed for AL use (probably yes, but check anyway)

...and "Nolox" is always a good idea with AL conductors and Lugs
Posted By: ITO

Re: Cu or Al - 03/06/07 06:56 PM

Also as an after thought, how long of run are we talking about?
Posted By: earlydean

Re: Cu or Al - 03/06/07 08:36 PM

also, an antioxident is generally required by the manufacturer's installation instructions for aluminum conductors when the conductors are terminated in a damp location.
Posted By: EV607797

Re: Cu or Al - 03/06/07 09:03 PM

I just learned that anti-oxidant paste is NOT an NEC requirement after decades of working in the electrical field. This is the kind of thing you just assume when working with others. That's the value in sites like this.

Back to the original question, yes, I would use and trust AL cable if the panel and meter base lugs are rated for it (few aren't, at least not in the past 40 years or so). If aluminum is installed correctly, it's a highly-efficient conductor. I agree that there may be local restrictions on using it, but I have yet to encounter any AHJ that prohibits it. That's usually more of a customer or building owner-level restriction.

#2AL is permitted by the NEC for residential 100 amp services, which is actually an exception since it's really not rated to handle 100 amps under other circumstances.

[This message has been edited by EV607797 (edited 03-06-2007).]
Posted By: ShockMe77

Re: Cu or Al - 03/06/07 09:20 PM

Better make sure that whatever you use to connect the copper to aluminum is rated for connecting copper to aluminum. Ideal makes a wirenut specifically for this purpose. Maybe they also make a bug (split-bolt connector) for an application like this as well. Is there anyway you can talk this customer into replacing the conductors back to the meter pan?

[This message has been edited by ShockMe77 (edited 03-06-2007).]
Posted By: Wizzie Electric

Re: Cu or Al - 03/06/07 09:39 PM

"Is there anyway you can talk this customer into replacing the conductors back to the meter pan?"

The plan is to replace them back to the meter pan.

The main breaker lugs are rated for Al and Cu. The run is about 6 feet.
Posted By: ShockMe77

Re: Cu or Al - 03/06/07 10:12 PM

I thought for some reason that you were splicing the conductors because they were short. D'oh!
Posted By: DougW

Re: Cu or Al - 03/07/07 05:39 AM

As ITO said, I'd run it past the local AHJ first, but as long as you're within the conductor's ampacity, WTH.
Posted By: gfretwell

Re: Cu or Al - 03/07/07 05:58 AM

310.15(B)(6) says it is OK but if this house has a big load that cycles like an HVAC they might see a little extra dimming of the lights with the aluminum. 20 some feet of #2 might seem expensive to him now but how much will it cost if you have to come back to install it later?
Posted By: ITO

Re: Cu or Al - 03/07/07 03:56 PM

What are we talking about here, $15 worth of copper wire?

On a side note my local AJH has some rules about AL in Dwellings.
Posted By: Wizzie Electric

Re: Cu or Al - 03/08/07 06:51 PM

I talked him into copper. thanks for the feedback.
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