Aluminum Conductors

[LarryFine]

The small conductors would flatten under the screw heads as they expanded from heat, and be looser causing more heat. Cycling loads would make the effect snowball until the connection overheated.

A thorough terminal tightening would restore contact, improved with the increased contact area with the flattened wire, and buy you another 40 years of use.

 

[Sea Nile]

A lot of references to copper not "work hardening" as quickly as aluminum "work hardens"..

What does 'work harden' mean?

 

[zbang]

Work hardening means that as the metal is "worked" by flexing* it loses ductility and actually becomes harder. Many metals do this and require periodic annealing to relieve stresses and soften the metal for further working. Silver and aluminum do this, Stainless is notorious for work-hardening (which make it more difficult to drill).

*which includes compression, and that even happens when cutting

 

[tortuga]

We doing mostly residential switch to aluminum at #1 AWG or 100 amps.
Not sure I know the reasoning other than that's what we always have done.

 

[jmellc]

I have nearly always used AL for service conductors and larger loads. Have sometimes used it for ranges & HVAC, though some HVAC specs copper conductors. Smallest I have used is #8 for a 30 amp dryer circuit. I only used it there because the supply house was out of 10-3 copper. AL isn't too bad if you don't have to pack it into a box or do sharp bends in it. I HATE troubleshooting 15 and 20 amp circuits with AL. It doesn't pack well, is bigger than the same load in copper. It nicks and breaks worse than copper. Some of the wirenuts that had to be used were the size of my thumb. Any wirenuts I bought for AL were very expensive and so were the devices. DO NOT USE for smaller circuits.

 

[don_resqcapt19]

I have nearly always used AL for service conductors and larger loads. Have sometimes used it for ranges & HVAC, though some HVAC specs copper conductors. Smallest I have used is #8 for a 30 amp dryer circuit. I only used it there because the supply house was out of 10-3 copper. AL isn't too bad if you don't have to pack it into a box or do sharp bends in it. I HATE troubleshooting 15 and 20 amp circuits with AL. It doesn't pack well, is bigger than the same load in copper. It nicks and breaks worse than copper. Some of the wirenuts that had to be used were the size of my thumb. Any wirenuts I bought for AL were very expensive and so were the devices. DO NOT USE for smaller circuits.

I though it was much easier to pack into the boxes than copper for the apartment complex I did with the single conductor aluminum in EMT. Sure it is larger, but much softer than copper. The wirenuts we used were the standard 451 and 452 wingnuts, but that was in the mid 70s and that design is not marked CU/AL now as it was then.
You do have to be careful stripping it, but if you use the correct size with your stripper tool, there is not an issue with nicking the conductor.

 

[Knuckle Dragger]

You do have to be careful stripping it, but if you use the correct size with your stripper tool, there is not an issue with nicking the conductor.

We were told/taught to shave off the insulation (especially with AL) as to avoid nicking the conductors.

 

[don_resqcapt19]

We were told/taught to shave off the insulation (especially with AL) as to avoid nicking the conductors.

we were told never to use a knife on the small aluminum...always use a wire stripper to avoid nicking the conductors.

 

[kwired]

As many have said the small,12 and 10 AWG conductors in particular, are what gave it the bad name.

Larger conductors back then had lesser issues. But today there is even less issues because they have improved alloys.

You don't even need to use any contact paste at terminations with today's alloys though many still do.

 

[ggunn]

There is still some reluctance by some to use aluminum conductors. I know a solar company that burned up the AC sections of a bunch of inverters because the guy who wired the AC conductors used aluminum wire with copper only crimp lugs. Their management then decreed "no more aluminum" even though what caused the heating was the resistive layer that formed between the aluminum wire and the copper lugs, not the aluminum itself.

 

[jmellc]

I though it was much easier to pack into the boxes than copper for the apartment complex I did with the single conductor aluminum in EMT. Sure it is larger, but much softer than copper. The wirenuts we used were the standard 451 and 452 wingnuts, but that was in the mid 70s and that design is not marked CU/AL now as it was then.
You do have to be careful stripping it, but if you use the correct size with your stripper tool, there is not an issue with nicking the conductor.

I haven’t seen the individual conductors, only old AL Romex. I can’t imagine running EMT through an entire house or apartment.

 

[don_resqcapt19]

I haven’t seen the individual conductors, only old AL Romex. I can’t imagine running EMT through an entire house or apartment.

I believe the 10 and 12 AWG aluminum using the new alloy was only available for a couple of years around 1975. I don't think the new alloy was ever used in NM.

Very common in my area...our local code does not permit cable wiring methods for over 6 apartments in a building, or for commercial occupancies. If you go to the City of Chicago and some of their suburbs, EMT is required for all dwelling units. The only cable wiring permitted by the Chicago code is NM for temporary wiring, and fishing AC or MC up to 25' in existing structures.

 

[jmellc]

I believe the 10 and 12 AWG aluminum using the new alloy was only available for a couple of years around 1975. I don't think the new alloy was ever used in NM.

Very common in my area...our local code does not permit cable wiring methods for over 6 apartments in a building, or for commercial occupancies. If you go to the City of Chicago and some of their suburbs, EMT is required for all dwelling units. The only cable wiring permitted by the Chicago code is NM for temporary wiring, and fishing AC or MC up to 25' in existing structures.

Must cost a fortune to wire a house or apartment there. I haven’t done new apartments in a long time but we always did them in Romex. About 1998, we wired a motel in Romex.

 

[don_resqcapt19]

Must cost a fortune to wire a house or apartment there. I haven’t done new apartments in a long time but we always did them in Romex. About 1998, we wired a motel in Romex.

It really doesn't. Our town has a new subdivision and we would permit NM. A Chicago area contractor is winning bids and installing EMT, the other contractors are bidding NM...that is a bit unusual, but for an contractor experienced in using EMT in a dwelling unit, the electrical cost will typically increase less than 15 to 17%. If you are an NM contractor and try to do it in EMT, your costs will go up over 50% because it is a totally different process.

 

[jmellc]

It really doesn't. Our town has a new subdivision and we would permit NM. A Chicago area contractor is winning bids and installing EMT, the other contractors are bidding NM...that is a bit unusual, but for an contractor experienced in using EMT in a dwelling unit, the electrical cost will typically increase less than 15 to 17%. If you are an NM contractor and try to do it in EMT, your costs will go up over 50% because it is a totally different process.

Sounds like a lot of work still. How are they routing pipe? I assume receptacles would be box to box down to crawl space? For lights, light box to light box, piping switch legs down? Lots of work, then more piping for any 3 or 4 way switches. I can’t picture it. My hat is off to him doing it profitably.

 

[ramsy]

What else should I know about AL conductors?

Contractors & their laborers can't be relied upon for skill or experience unique to AL termination treatment, temperature limits, or torque.

Employees require the most idiot proof equipment and common procedures possible.

 

[don_resqcapt19]

Sounds like a lot of work still. How are they routing pipe? I assume receptacles would be box to box down to crawl space? For lights, light box to light box, piping switch legs down? Lots of work, then more piping for any 3 or 4 way switches. I can’t picture it. My hat is off to him doing it profitably.

Yes lots of ups and downs and often taking care that when the wire path passes through a box that the raceways are lined up so you can pull straight through and then come back and pull loops in the conductors that need to terminate in that box.

When everyone has to use the same wiring methods there is no issue with making a profit...I am a bit surprised that the one contractor is coming out ahead using EMT against NM...it was not a one time thing...he has been doing about half of the units in that subdivision over the past 4 or 5 years.

 

[letgomywago]

Yes lots of ups and downs and often taking care that when the wire path passes through a box that the raceways are lined up so you can pull straight through and then come back and pull loops in the conductors that need to terminate in that box.

When everyone has to use the same wiring methods there is no issue with making a profit...I am a bit surprised that the one contractor is coming out ahead using EMT against NM...it was not a one time thing...he has been doing about half of the units in that subdivision over the past 4 or 5 years.

Was it possibly for filler work for the guys / training for them. If he's not after a profit i could see it. The savings on breakers after 2017 nec using afci/gfci devices and multiwire home runs I could see it being cheaper than cable if using nailstraps not 1 hole, fast cheap employees, and then only ranch style houses with unfinished basement or deep crawl spaces.

 

[don_resqcapt19]

Was it possibly for filler work for the guys / training for them. If he's not after a profit i could see it. The savings on breakers after 2017 nec using afci/gfci devices and multiwire home runs I could see it being cheaper than cable if using nailstraps not 1 hole, fast cheap employees, and then only ranch style houses with unfinished basement or deep crawl spaces.

Not filler work...I talked to him a couple of times when I was inspecting his jobs because our inspector was on vacation. The process is just so different, his guys could not make him any money if they tried to install NM. There are a lot of things an experienced crew learns about how to install EMT in wood framed buildings. Have never seen anything other than a J nail used for these types of projects.

 

[SSDriver]

Never had any issues with aluminum Feeders, ser, or NM to jboxs for HVAC or ranges.

Most of the schools and colleges I do work for have all the Feeders in AL now. All the houses in my neighborhood have #6 aluminum feeding HVAC disconnects for over 30 years without any issues. From disconnect to HVAC is copper wire.

Only issues I've ever seen in the field were branch circuits at devices not rated for AL.