AL conductors

[charlie b]

We have a general rule for the use of AL. We show AL for feeders exceeding 100 amps, and CU everywhere else. But I don't have a good reason to draw the line there. I know this is not a code issue, but can anyone offer a reasonable basis for using AL versus CU on conductors of any specific size?

 

[jumper]

Are you looking for something beyond cost as a basis?

For me, #8 and above is usually aluminum. Cheaper.

 

[petersonra]

Are you looking for something beyond cost as a basis?

For me, #8 and above is usually aluminum. Cheaper.

But don't you sometimes end up with larger conductors and thus larger and more expensive conduit? Or does the lower cost of the conductors always mitigate that?

 

[jumper]

But don't you sometimes end up with larger conductors and thus larger and more expensive conduit? Or does the lower cost of the conductors always mitigate that?

Sometimes CU works out better because of sizes, ampacity, etc, but AL seems to be the winner more often than not now. Did not seem to be so often in years past.

 

[Dennis Alwon]

If it were not for cost I would use copper everywhere. I still use it a lot but the cost is so much greater. I generally used copper for cables up to #6. When I have conduit pulls I will usually stay with copper to #2 or #4

 

[infinity]

We only use copper even up to 750 kcmil because that what's specified by the guy paying the bills. Personally I think that larger Aluminum conductors are fine but if there is an issue it's with the terminations. A crimped on lug can mitigate any problems with the terminations down the road.

 

[iceworm]

We only use copper even up to 750 kcmil because that what's specified by the guy paying the bills. ...

True for me as well. All my customers spec copper. Even small transformers (say 225KVA and below.) are speced copper. I finally have gotten a few to consider accepting Al XFM. They have not accepted yet - just considering. Except for minor temporary power, none will consider AL conductors - and even those are mostly copper.

AFAICT AL xfm are equally reliable as CU wound. And I suspect there is nothing wrong with AL conductors - of any size. I have not done any AL conductor reliability research, but I highly suspect the issues with even small AL conductors went away when the spec was changed - maybe 30 years ago.

That's about the same time the reliability of the AL wound xfm went way up. With xfm it wasn't the material composition spec that change, but rather, that's when the mfg learned to make good internal connection welds.

edit to add: I think the good ole boys are stuck with the way grandad did it. Wait a minute - I'm older than most of the GOBs:?

ice

 

[iceworm]

If it were not for cost I would use copper everywhere. ...

Interestingly, for my own house, with the exception to the underground 150' 4/0 AL service conductors, it is all CU - as well as the #14, #12, #10 CU, there are some #8, #6, and #2 feeders - all are CU.

Hummmm - Maybe I'm more stuck that I think I am.

ice

 

[Dennis Alwon]

Interestingly, for my own house, with the exception to the underground 150' 4/0 AL service conductors, it is all CU - as well as the #14, #12, #10 CU, there are some #8, #6, and #2 feeders - all are CU.

Hummmm - Maybe I'm more stuck that I think I am.

ice

Yeah, my house is all copper and all 12 awg and larger. Those were the days back when wire was cheap.

 

[ActionDave]

Trying to get folks to use AL instead of CU is like trying to convince American football fans to watch soccer.

 

[petersonra]

UL508a does not allow us to use AL wire at all or I would be on it. It could be an easy way to save a few bucks on larger wires. I asked one of the UL engineers once if there was any chance of them letting us use AL wire in UL508a panels. He said he was not aware of anyone who had gotten permission to do so and suggested we could pay them to investigate the idea.

 

[cdslotz]

Most municipalities around here have a minimum size and above allowed for AL.

I think Dallas is #1 or larger

 

[charlie b]

Thanks for the comments, everyone. This issue arose from a value engineering suggestion by the electrical contractor. The suggestion was to use AL for feeders and branch circuits that would use #4 or larger conductors. I knew that there would be no code requirement to prohibit this change. I wanted to know if there were any installation or maintenance reasons that would give a basis for resisting the change.

 

[Shoe]

I have a similar outlook (100 amps and larger) and for feeders only. My thought is that a branch circuit may feed something that is not rated for aluminum conductor termination. There is a lot of equipment that indicates "copper conductors only" for the branch circuit feeding this equipment (rooftop units, medical imaging etc.). I also do not use aluminum to terminate to any vibrating equipment.

The 100 amps and larger seems to be a good number for me because it keeps the aluminum away from most of the sizes for your typical branch circuits.

 

[MasterTheNEC]

Charle- What are your specific concerns. Being that I happen to work for a company that manufacturers both I would be more than happy to address any of your ASTM compliance concerns and other concerns over AL vs. CU.

Again we make building wire products using both materials...so what do you want to know from a development, production, testing and compliance standpoint?

 

[Fulthrotl]

Thanks for the comments, everyone. This issue arose from a value engineering suggestion by the electrical contractor. The suggestion was to use AL for feeders and branch circuits that would use #4 or larger conductors. I knew that there would be no code requirement to prohibit this change. I wanted to know if there were any installation or maintenance reasons that would give a basis for resisting the change.

#4 is a good break point.

anything larger, it's aluminum, with a couple caveats:

first, i won't use anything other than simpull, by southwire.
i got snookered on the last job into trying someone else's
flavor of simpull. i'll never do that again. ever. lotta long feeders
in pvc underground.... used 40 gallons of lube, and almost broke
the pull rope on the first pull, which was 700' long or so, and i started
it dry. what a nightmare. the wire was cerro. never again.

ilsco lugs, butt splices, etc. done with the specific die, not a ranging die
or dieless. no setscrew lugs, ever. where i have to hit a breaker or setscrew
lug, i use ilsco offset finger lugs, with the panduit heat shrink.
no chinese lugs. i've had them split.

for bolted connections, grade 8 3/8-24 allen head cap screws, washers, and nylocks.
you can torque them to 37 ft. lbs. you could use 1/2", but the lug material is starting
to flow at 37, so it seems overkill. on the last piece of switchgear i made up, i had
two "grade 5" bolts twist off at around 15 ft lbs.

on top of that, panduit 600 volt direct burial listed self vulcanizing heat shrink,
on lugs and butt splices, and finger lugs. no exceptions.
you end up with a hermetically sealed connection.

it's as good a means as copper, and it's running 22% of the price of copper.
this is tomorrows pull... i have seven pulls to make that will eat most of this up.
the difference in price between this and copper is about $75,000. hard to justify it.

 

[don_resqcapt19]

Most of the resistance to the use of aluminum comes from the poor performance of 15 and 20 amp aluminum branch circuit conductors in the late 60s.

In the early 70s they started using a new alloy for the 15 and 20 amp sized conductors and where that was used along with CO/ALR devices there were no more problems than with a copper system. However the new alloy 15 and 20 amp conductors were only on the market a couple of years as the product did not sell because of the problems with the older wire. I was kind of expecting it to come back on the market when copper prices spiked, but it didn't.

 

[MasterTheNEC]

#4 is a good break point.

anything larger, it's aluminum, with a couple caveats:

first, i won't use anything other than simpull, by southwire.
i got snookered on the last job into trying someone else's
flavor of simpull. i'll never do that again. ever. lotta long feeders
in pvc underground.... used 40 gallons of lube, and almost broke
the pull rope on the first pull, which was 700' long or so, and i started
it dry. what a nightmare. the wire was cerro. never again.

ilsco lugs, butt splices, etc. done with the specific die, not a ranging die
or dieless. no setscrew lugs, ever. where i have to hit a breaker or setscrew
lug, i use ilsco offset finger lugs, with the panduit heat shrink.
no chinese lugs. i've had them split.

for bolted connections, grade 8 3/8-24 allen head cap screws, washers, and nylocks.
you can torque them to 37 ft. lbs. you could use 1/2", but the lug material is starting
to flow at 37, so it seems overkill. on the last piece of switchgear i made up, i had
two "grade 5" bolts twist off at around 15 ft lbs.

on top of that, panduit 600 volt direct burial listed self vulcanizing heat shrink,
on lugs and butt splices, and finger lugs. no exceptions.
you end up with a hermetically sealed connection.

it's as good a means as copper, and it's running 22% of the price of copper.
this is tomorrows pull... i have seven pulls to make that will eat most of this up.
the difference in price between this and copper is about $75,000. hard to justify it.

You would not need to set up those reels on blocks or jacks if you had the "Reel Payoff" type reels...

 

[ceb58]

Yeah, my house is all copper and all 12 awg and larger. Those were the days back when wire was cheap.

When I wired my oldest son's house it was all #12 and larger Cu. #12 was $90.00 per 1000 ft. Daughter-in-law said she wanted plenty of receptacles, I put one every 6 ft.

 

[John120/240]

You would not need to set up those reels on blocks or jacks if you had the "Reel Payoff" type reels...

What are Reel Payoff type reels ??? Well with Google I found this You Tube demostration. ....https://www.youtube.com/watch?v=Gffwx243ETc....Now why didn't I think of this