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#180486 - 08/27/08 03:14 PM aluminium versus copper
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1286
Loc: Alaska
here is some interesting info I came across today. Recommend Practices for Installing Aluminium wiring and Cable

Especailly after the discussion on the use of aluminium SER cable on the message board.
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#180491 - 08/27/08 05:17 PM Re: aluminium versus copper [Re: sparkyinak]
renosteinke Offline
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Registered: 01/22/05
Posts: 5300
Loc: Blue Collar Country
Thank you, Alaska, for the link! Now ... for a few comments ....

NECA standards are wonderful guides, and often referenced by contract as defining 'good workmanship.' While note 'code,' as such, they certainly help define proper practice.

I've never seen a document, though, that both asserted a copyright, and also omitted a date. I know not the year of this standard - but a reference to the 1999 NEC shows it to be of recent vintage.

The date is important, as the alloy that was used in aluminum wire was changed in the late 70's. Our friends in the aluminum wire market are today making the seminar rounds, aggressively marketing their wares. It is their contention that this newer allow is completely free from the issues associated with the earlier alloy.

Of greater concern is the details of application. The reps are denying the need to coat the wires with anti-oxidant, let alone 'work it in,' as us oldsters were taught. According to them, there is no more need to coat aluminum wire than it is copper wire .

Looking at that NECA standard, I see that it assumes that anti-oxidant will be 'worked in' no matter the connection method. While it does refer to also coating copper wire 'where needed' -something not further defined- the instructions for the various connection methods all assume coating with anti-oxidant.

There is no mention of wire nuts, of any sort, as a connection method. This is interesting, since there are at least two 'wire nut' type connectors marketed for this use.

Which brings up another assumption to the piece: that aluminum will be used only for larger wires. While there is no specific prohibition of aluminum wire for smaller branch circuits to be found in the NEC, no one makes the wire in sizes smaller than #6. Pure chance, I suppose.

Though this was not always the case; I just removed several hundred feet of aluminum "romex" (#10 and #12) from a mobile home.

Finally ... a note about devices ....

While aluminum rated devices are available, there are no such rated GFCI's. I saw today that the 'usual' range receptacles carry an aluminum rating as well.

I know, I've drifted from the original thread - which was about aluminum as a FEEDER conductor. I have no problem with that. I'm not so sure about it's use for large appliances (ranges, air conditioners, etc.) There I would want to be sure that the device, or disconnect, was rated for the use.

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#180496 - 08/27/08 07:07 PM Re: aluminium versus copper [Re: renosteinke]
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1286
Loc: Alaska
 Originally Posted By: renosteinke
...I've drifted from the original thread - which was about aluminum as a FEEDER conductor.
No you didn't. That was a different thread.

I am looking at using aluminium #6 and larger providing they are compact aluminium. Another attribute of compact aluminium is the aluminium equal to copper is actually smaller in diameter. in other words, although you would need a 4/0 aluminium conductor in place of a 3/0 copper, the 4/0 is actually narrower then a 3/0. This means no need to up size a conduit to accomodate the "larger" wires. This is also a benefit if the existing copper conductors in a raceway need replacing like to damage. If the customer will accept aluminium, they can save a few pennies. Outside of the difference ampacity size for size and terminal requirements, if you can ignore the stigmatism of old AL wire, why not use aluminium?
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