ECN Forum Forums Code Related Discussion NEC & other Code issues Aluminum conductors

Are aluminum conductors allowed for all feeders and branch circuits? Code sections? If someone can guide me to a previous thread on this, that would work too. Thanks.

Technically, as the code is written, there's no reason not to use aluminum for nearly everything. True, there are a few exceptions, such as certain grounding conductors where the NEC specifies theat aluminum shall NOT be used, but those are the exceptions.

Indeed, the aluminum wire makes will tell you that aluminum is every bit as reliable as copper.

Yea, right. The wire makers leave out a few details:

They neglect to mention the change they made in the alloy used in the late 70's, to address issues that - they still claim - were caused by poor installation.

They also neglect to point out that they don't make the stuff smaller than #6 anymore. So, while there's no rule against using all aluminum to wire a house, lots of luck finding that #12 Romex in aluminum.

The same paradox exists as to the use of anti-oxidant compounds. The wire makers say there is no more, or less, reason to coat aluminum than there is copper. The NECA standard seems to assume that you will use it when working with aluminum, but doesn't specifically tell you to use it. The NEC is silent on the issue.

This is -yet again - where 'trade practice' varies from what the rule books say. Personally, I'll stick with tradition.

Check with the local AHJ as to the minimum sizes allowed.
Most of them have no problems with Aluminum feeders but do have a cutoff size that they won't allow to be anything but Copper.
Around here, it's usually 10AWG and smaller, but it pays to check it out.

So where/how does 110.5 apply?

PLEASE, please, please don't tie copper and alu together under a wire nut, even if "they" say that the nut is made specifically for that purpose.

Who are the "they" you're talking about? Do you know something that UL doesn't or have you fallen for the scare tactics on one of the web pages that I swear is funded by the makers of the copalum splices?

The only drawback I can see to the wirenut that is listed for copper to aluminum is its large size, hard to jam back in those undersized boxes they use in the old mobile homes.

Personally Tom,
There is absolutely no way that I would EVER put an aluminium wire and a copper wire in the same termination and call it "safe".

Sure the copper wire might be fine, but screwing a wirenut over an aluminium wire, is just asking for trouble.

These sorts of connections depend on friction only, not the sort of thing you want to subject aluminium to, as it has the habit of "flowing" under mechanical stress.

Especially when these connections are also carrying current, which will heat any sub-standard connection up, possibly to the melting point of the metal.

Bi-metallic lugs and splices are there to be used for a reason, otherwise, we wouldn't have them.

UL= Underwriters Laboratories. The clue is in the name. If a product is approved, then it must have passed their tests, surely?

Not sure if this relates to the OP's question or not, but the thing I find a little unnerving about the Ideal purple wirenuts, is that the manufacturer has multiple warnings on the package that they are designed only for connecting aluminum-to-aluminum conductors with another copper conductor present, but not for straight aluminum to aluminum only.
Not sure about the T&B Marette ACS wirenut though, but according to the T&B product literature, they are not even UL Listed, so not sure how you could actually use them.
If I need to splice small AWG aluminum to aluminum or aluminum to copper, which thankfully is a rare occurrence for me, I use the AlumiConn set screw type connectors and a torque screwdriver, so as to make it a UL Listed splice. These still can take up a lot of room in a box, but IMO they are presently the next best alternative to the actual Copalum splices

One thing a lot of people seem to ignore is that most lugs are aluminum. It would seem (as Alcan, among others will say) aluminum wire performs better in these lugs than copper.