why aluminum wiring?

[vavet]

I know there is a troubled history with using aluminum wiring for regular house wiring, but I also know it's still used for larger feeder wires to secondary structures, like my detached garage.

WHY?

Are the concerns with using aluminum for regular house wiring somehow alleviated when you increase the size from 14 ga to 2ga?

I'm sure there's a right combination of words to google to find this answer, but I can't find it. Someone here knows the answer. Will you tell me?

 

[moab11]

mainly price, aluminum cable is much cheaper than copper.
As long as the proper grease is used on the ends and terminated properly, there is no issues even in residential. The main issues are improper installations and retrofits.

I believe almost all high voltage transmission lines are also aluminum for the cost savings.

 

[Yankeefarmer]

The original aluminum wiring that caused problems was a different alloy than currently used.
https://codecheck.com/aluminum-wiring/

 

[Norcal]

Aluminum is cheaper then copper, the smallest I would use is 6 AWG, but just don’t like to use it below 2 AWG, installed correctly there are no issues, sloppy installs with either copper or aluminum are going to cause problems. In my own house every feeder 100A and greater is aluminum alloy been that way for 27 years with no problems. BTW, there is a proposal to add 14 AWG copper clad aluminum to the next NEC, so contractors will have to add 10A circuit breakers to the inventory. Currently 12 AWG is the smallest aluminum conductor allowed.

 

[NUTTSGT]

I asked a similar question several years ago, there's a couple of good posts and a link about it.

https://www.garagejournal.com/forum/showthread.php?t=297024

 

[dcg9381]

$ is the bottom line.
Using it as a feed - there is a lot less opportunity to screw it up than using it as branch circuits..

 

[Sumboodie]

Weight too.

 

[Mike Folks]

Will Aluminum be used in extension cords(stranded of course for flexibility)?

 

[rlitman]

Will Aluminum be used in extension cords(stranded of course for flexibility)?

Copper coated aluminum has been in jumper cables and cheap low voltage wire for years now. I avoid that **** at all costs.

 

[Bert_]

Aluminum was problematic when used for branch circuits. Look at the screws on an outlet and compare it to the lugs in a panel, it's apples to oranges. Can also use crimp on lugs, they basically never go bad.

Copper hasn't been used for outside services for a long time. Most every overhead or underground wire is aluminum.

 

[yeldogt]

It's a connection problem not a wire problem ...

As long as you have the proper termination you will have no issues

 

[dogdog]

I asked a similar question several years ago, there's a couple of good posts and a link about it.

https://www.garagejournal.com/forum/showthread.php?t=297024

^^^
Yup war shortages... copper used in ammunition, casing and jackets ... I am not sure if those GanjaNinja have anything to do with the decision to go Aluminum... it was the Flower child hippie days also.

saw a few home that was build in the 1970s and all home wiring was aluminum. they are sized 1 size bigger that the copper counter parts... so 20AMP uses 10Ga, and 15amp uses 12Ga aluminum wiring.

Aluminum in Chemistry or physics conducts better than copper btw in it's pure form without the environmental variables.

Just like Silver conducts better than Gold.

It's all about the valance/free electrons if I remember the science class correctly.

 

[rlitman]

It's a connection problem not a wire problem ...

As long as you have the proper termination you will have no issues

For the most part, yes. With branch wiring, it can also be a wire problem however.

...Aluminum in Chemistry or physics conducts better than copper btw in it's pure form without the environmental variables...

Absolutely not. Pure copper conducts better than pure aluminum, and all alloys of either conduct worse than the pure forms. Silver conducts better than both, and gold is at the bottom of this list of four.

 

[EricS]

It's a connection problem not a wire problem ...

As long as you have the proper termination you will have no issues

The other half of that equation is the device the wire is being terminated to is rated for AL wire.
A lot of residential devices(switches ,receptacles) are rated for CU wire only.

 

[dogdog]

The other half of that equation is the device the wire is being terminated to is rated for AL wire.
A lot of residential devices(switches ,receptacles) are rated for CU wire only.

Pig tails are still legal I think.

 

[dogdog]

For the most part, yes. With branch wiring, it can also be a wire problem however.



Absolutely not. Pure copper conducts better than pure aluminum, and all alloys of either conduct worse than the pure forms. Silver conducts better than both, and gold is at the bottom of this list of four.

Something about this is not right, I just don't remember it... it's something about free valence electrons...

 

[TTMotorsports]

I ran aluminum wiring from my house panel to the shop panel. Going up in size since it was aluminum still was half as much as copper. A little of the correct grease on the ends and won't be an issue. My neighbor who is an electrician said almost all the 125amp and up sub panels the run is aluminum wire. Going up in conduit size for ease of pulling was a no brainer as well. For 220' it didn't cost that much more for the next 1/2" larger conduit and made pulling it very very easy

 

[James-W]

I know a lot of people have used, and are currently using, aluminum wire and they are not having any issues with it. As for myself, I prefer to use copper wire even though it costs a bit more. Not that there is anything wrong with aluminum wire, it is just that I am an old fart and set in my ways. I just prefer copper wire because I have always used it and it is hard to change and do something different.

 

[wyliesdiesels]

I ran aluminum wiring from my house panel to the shop panel. Going up in size since it was aluminum still was half as much as copper. A little of the correct grease on the ends and won't be an issue. My neighbor who is an electrician said almost all the 125amp and up sub panels the run is aluminum wire. Going up in conduit size for ease of pulling was a no brainer as well. For 220' it didn't cost that much more for the next 1/2" larger conduit and made pulling it very very easy

what youre referring to is NOT greasem its anti-ox paste and is not required unless the manu. calls for it. most wire manufacturers dont...

 

[EricS]

Pig tails are still legal I think.

It is here, there are specific wire nuts(al to cu) for joining the copper to aluminium to create the pig tails.
The issue was people removing the old device and just terminating the original aluminium wire onto the new replacement device.

 

[finn]

As pointed out, it’s a connection problem with aluminum, not a wire proble.

Typical feed from the meter has to the panel. three connections at each end. Pretty easy to get that right .

My living room has something like 24 devices, each having, at a minimum, two connections, with most having four or more (not counting the grounds). That’s between 50 and 100 points to make a mistake and miss or inadequately apply the anti oxidation paste in that one room.

 

[alfredeneuman]

That’s between 50 and 100 points to make a mistake and miss or inadequately apply the anti oxidation paste in that one room.

No manufacturers presently require the use of anti-oxidant, and the Code doesn't call for it unless the manufacturer says so.
It's use is optional

 

[Fasthotrod]

^^^
Aluminum in Chemistry or physics conducts better than copper btw in it's pure form without the environmental variables.

Just like Silver conducts better than Gold.

It's all about the valance/free electrons if I remember the science class correctly.

Absolutely not. Pure copper conducts better than pure aluminum, and all alloys of either conduct worse than the pure forms. Silver conducts better than both, and gold is at the bottom of this list of four.

Something about this is not right, I just don't remember it... it's something about free valence electrons...

Electrical conductivity for metals:

Silver - 62,1 10.E6 Siemens/m
Copper - 58,7 10.E6 Siemens/m
Gold - 44,2 10.E6 Siemens/m
Aluminum - 36,9 10.E6 Siemens/m

https://www.tibtech.com/conductivite.php?lang=en_US

You are correct about the valence electrons. Per this article: https://www.allmetalsfab.com/metal-best-conducts-electricity/

"Why is silver at the top of the list? The presence of valence electrons determines a metal’s conductivity. Valence electrons are “free electrons” that allow metals to conduct electric current. Free electrons move through metal like billiard balls, transferring energy as they knock into each other. Silver and copper are metals with single, free-moving valence electrons. The valance moves throughout the metal with little resistance, making these metals more conductive.

Silver has the highest conductivity of all metals, but it also has a hefty price tag and it can tarnish, rendering the surface less conductive. Gold is more corrosion resistant. Copper’s high conductivity and affordability make it a more appealing choice."

Hope this helps.

Mark

 

[rlitman]

...Silver has the highest conductivity of all metals, but it also has a hefty price tag and it can tarnish, rendering the surface less conductive...

On this note, silver sulphide (tarnish) is still far more conductive than either copper oxide or aluminum oxide (and silver oxide doesn't form in ambient conditions), which is why silver plating is often used in high power applications. Also, on switch contacts, silver sulphide is soft, and breaks up to give you good contact under the forces switch contacts see (in fact, wiping action is often engineered into many contact systems to break through oxide layers).

But it does form relatively quickly, and can affect low voltage applications (especially in places where there is no movement), which is where gold plating comes in.

 

[n8n]

Aluminum is cheaper then copper, the smallest I would use is 6 AWG, but just don’t like to use it below 2 AWG, installed correctly there are no issues, sloppy installs with either copper or aluminum are going to cause problems. In my own house every feeder 100A and greater is aluminum alloy been that way for 27 years with no problems. BTW, there is a proposal to add 14 AWG copper clad aluminum to the next NEC, so contractors will have to add 10A circuit breakers to the inventory. Currently 12 AWG is the smallest aluminum conductor allowed.

What would you use a 10A circuit for? The only use I can think of is residential lighting, now that LEDs are commonplace, you might not need a 15A circuit anymore. In that case I think I might rather have two 10A circuits so I'm not completely in the dark if there's a fault.

 

[Norcal]

What would you use a 10A circuit for? The only use I can think of is residential lighting, now that LEDs are commonplace, you might not need a 15A circuit anymore. In that case I think I might rather have two 10A circuits so I'm not completely in the dark if there's a fault.

I really see no reason for it myself, there were contractors who were using 10A circuit breakers in a attempt to evade AFCI requirements years ago, not even too sure about copper clad aluminum, but it’s cheaper then copper without the need of expensive connectors to terminate it, since CO/ALR, AL/CU, devices and connectors are not required.

 

[bigdav160]

My 50+ year old home still sports it's "built with" original aluminum wires.

I will say the Federal Pacific Stab Lok panel is gone though.

 

[nadogail]

I am of the opinion that aluminum wire is used to save money and weight.

If there are other reasons for using aluminum, I am open to learning about them.

 

[BillD]

I am of the opinion that aluminum wire is used to save money and weight.

"Saving money" seems to have a negative connotation attached to it nowadays. Thanks "the media"!

Of course, as a rule of thumb, implementing the most economical solution to a problem is what is done in most human endeavors.

Many factors go into calculating what is most economical. Safety, material costs, labor costs, maintenance, etc.

Probably the biggest reason why aluminum wire is used in transmission lines is weight. Support towers need to be spaced further apart. The cost of tower installation and maintenance probably is much greater than the difference between materials costs of the cable.

 

[Bopbop]

When i had my new shop wired 2 years ago I went with copper. The cost difference was about $500.00 to run a 200 amp service 150 feet. The savings for aluminum was not worth it.
I work for a commercial engineering design firm and our electrical engineers always use copper for the base design. Aluminum is the VE item that comes up to save money.

 

[Norcal]

When i had my new shop wired 2 years ago I went with copper. The cost difference was about $500.00 to run a 200 amp service 150 feet. The savings for aluminum was not worth it.
I work for a commercial engineering design firm and our electrical engineers always use copper for the base design. Aluminum is the VE item that comes up to save money.

Still nothing wrong with aluminum except ignorance, a properly installed aluminum conductor will provide trouble free service throughout its lifetime and a improperly installed copper conductor will cause damage just as much as a aluminum conductor.

 

[wyliesdiesels]

When i had my new shop wired 2 years ago I went with copper. The cost difference was about $500.00 to run a 200 amp service 150 feet. The savings for aluminum was not worth it.
I work for a commercial engineering design firm and our electrical engineers always use copper for the base design. Aluminum is the VE item that comes up to save money.

Did you ask your PoCo to run copper overhead drop or underground lateral to your meter base too? how about copper for the underground primary lines?

 

[Bert_]

When i had my new shop wired 2 years ago I went with copper. The cost difference was about $500.00 to run a 200 amp service 150 feet. The savings for aluminum was not worth it.
I work for a commercial engineering design firm and our electrical engineers always use copper for the base design. Aluminum is the VE item that comes up to save money.

Did you ask your PoCo to run copper overhead drop or underground lateral to your meter base too? how about copper for the underground primary lines?

Pretty much. You install your 200A service with copper. Utility will come and crimp a #2 aluminum to it.

 

[yeldogt]

The other half of that equation is the device the wire is being terminated to is rated for AL wire.
A lot of residential devices(switches ,receptacles) are rated for CU wire only.

That's why I said connection problem ...

 

[yeldogt]

For the most part, yes. With branch wiring, it can also be a wire problem however.



Absolutely not. Pure copper conducts better than pure aluminum, and all alloys of either conduct worse than the pure forms. Silver conducts better than both, and gold is at the bottom of this list of four.

I don't understand how it can ever be a wire problem ... ?

Back in the 70's they had 14 and 12 wire equivalent ...... it was the connections.

What's the smallest AL cable today ... ? 40 amp ? The last i need 30 amp for an AC it was Cu

 

[alfredeneuman]

The last i need 30 amp for an AC it was Cu

Most (if not all) incoming line terminals on AC aren't rated for Al wire.

 

[yeldogt]

Most (if not all) incoming line terminals on AC aren't rated for Al wire.

My suburban place I know both units are AL -- they go to a disconnect. The whips to the units are stranded copper. Same with larger mini ...

I believe this is very common ... at least around me. I'm sure when CU is cheap -- they use CU.


My new build had 90amp AL cable to an exterior sub at the 3 AC units ..

 

[Bert_]

We don't run much aluminum for residential AC's. A 2 1/2 ton is a real common size, it runs on #12. No savings to be had and then you have to carry another product. Maybe in another part of the country where big AC's are common it would make more sense.

I'll run aluminum to electric air handlers. Pretty common to have around 15 KW of resistance heat. #2 aluminum works great.

 

[yeldogt]

We don't run much aluminum for residential AC's. A 2 1/2 ton is a real common size, it runs on #12. No savings to be had and then you have to carry another product. Maybe in another part of the country where big AC's are common it would make more sense.

I'll run aluminum to electric air handlers. Pretty common to have around 15 KW of resistance heat. #2 aluminum works great.

My old 4T York ... was a 30amp line ... When I did the new 3T Carriers and even the 2.5 ton Mitsubishi mini-split needed 40amp lines .. this was 5 years ago.

Weird ... some of the new equipment has min higher than the old stuff.

 

[Bert_]

Maybe something that's not being considered is that with a A/C condensing unit wire size and breaker size are not exactly related.

I can find loads of 5T units that run on 40A wire, but they also take a 60A breaker. Same with the 2.5t I talked about, #12 wire but usually takes a 30A breaker. Even a lot of contractors don't really grasp that.