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AL branch circuit wiring.

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Muneepit

Muneepit
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Houston
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Electrician
Is it still legal, ( Not that I would do it), to wire a house with AL conductors for the branch circuit wiring?

Or does the NEC prohibit AL wiring for branch circuits. I was under the impression it does prohibit, but unable to locate it in the NEC.
 
don_resqcapt19

don_resqcapt19

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Illinois
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retired electrician
There is no 10 and 12 AWG aluminum on the market at this time, so you cannot use aluminum for 15 and 20 amp branch circuits, unless you want to use 8 AWG.

I believe there is 10 and 12 AWG copper clad aluminum on the market that can be used for 15 and 20 amp branch circuits.
 
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winnie

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Springfield, MA, USA
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Electric motor research
Agreed: Al wire is not prohibited, however suitable devices are required to use it. As a practical matter using Cu conductors for small branch circuits is probably cheaper.
 
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Muneepit

Muneepit
Location
Houston
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Electrician
Thanks. I had someone ask me if I thought is was allowed by the NEC. I answered no. He said wrong. Yes it is. Nowhere in the NEC does it prohibit AL wire for residential branch circuits. I thought that was odd, given all of the issues with it.
 
don_resqcapt19

don_resqcapt19

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Illinois
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retired electrician
Muneepit said:
Thanks. I had someone ask me if I thought is was allowed by the NEC. I answered no. He said wrong. Yes it is. Nowhere in the NEC does it prohibit AL wire for residential branch circuits. I thought that was odd, given all of the issues with it.
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It has never been prohibited by the code. There were a lot of issues with the old alloy aluminum 15 and 20 amp conductors.
For a short period of time in the mid 70s, the new alloy aluminum conductors in 10 and 12 AWG were on the market as single conductors. I don't think any NM was ever produced using the new alloy.

The contractor I was working for did an apartment complex in 74-75 using the single conductor aluminum conductors in sizes 10 and 12 AWG. We did the service work for that project and for some other similar projects built using copper conductors for many years. There were no more issues with the aluminum project than there were with the copper project.

It was cheaper, easier to install, and had no more problems than copper, but the product was only on the market in those conductor sizes for a few years as they could not overcome the bad reputation of the old aluminum that was problematic.

I believe there is copper clad aluminum in both NM and single conductors on the market at this time in those sizes, but I have never worked with it. As far as I know, there is no plain aluminum conductors on the market at this time in the 15 and 20 amp sizes.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Muneepit said:
. Nowhere in the NEC does it prohibit AL wire for residential branch circuits. I thought that was odd, given all of the issues with it.
Click to expand...

IF you think about it, that would not be a logical thing to think. First off, we of course use aluminum for services and feeders all the time. We commonly think of branch circuits as being "small" but branch circuits can be very large. For example, article 210 has a ground fault protection for equipment provision for branch circuits of 1000A or more (210.13) which harmonizes with the GFP requirements for services and feeders. Secondly, We (or at least I) use aluminum for branch circuits all the time. I usually use #6 SER for ranges. That is the most common example for (resi) branch circuits, but I have used it on occasion for larger branch circuits like duct heaters, on demand electric water heaters, and HVAC. I think perhaps the more logical thing would be to think there is a minimum conductor size requirement which there isnt (well there is, but it still goes down small enough for 15 and 20 amp branch circuits, 310.106(A)).
 
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