why aluminum wiring?

[brewchief]

I see a ton of A/Cs wired with #6 seu cable, cheap, works for pretty much any size and can be run outside as needed, can also be stapled to bottom of joists in basements IIRC.

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[alfredeneuman]

I see a ton of A/Cs wired with #6 seu cable, cheap, works for pretty much any size and can be run outside as needed, can also be stapled to bottom of joists in basements IIRC.

Don't you mean type ser cable? AFAIK There is no such thing as type seu, and type use is prohibited for use indoors.

 

[brewchief]

Don't you mean type ser cable? AFAIK There is no such thing as type seu, and type use is prohibited for use indoors.

https://www.wireandcableyourway.com/6-6-6-aluminum-seu-service-entrance-cable

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[alfredeneuman]

Unless I missed something it's regular SE cable.
I'd never heard of it with the "U" designation. Thanks for cluing me in.
Have you seen it hooked to the actual terminals on the AC, or are they landed on a disconnect or something?

 

[brewchief]

Unless I missed something it's regular SE cable.

I'd never heard of it with the "U" designation. Thanks for cluing me in.

Have you seen it hooked to the actual terminals on the AC, or are they landed on a disconnect or something?

I've seen it run directly to an AC although it shouldn't have been as the contactor was rated for copper only. It's commonly run from panel to disconnect, doesn't need any additional covering outside.

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[alfredeneuman]

I've seen it run directly to an AC although it shouldn't have been as the contactor was rated for copper only.

This subject started when I said that in post 36

 

[Bert_]

Don't you mean type ser cable? AFAIK There is no such thing as type seu, and type use is prohibited for use indoors.

I've always known seu as 2 insulated and 1 bare conductor.

Ser is 3 insulated plus 1 bare.

 

[wyliesdiesels]

I've always known seu as 2 insulated and 1 bare conductor.

Ser is 3 insulated plus 1 bare.

not according to southwire who makes a 2-cnd w/ gr SER...

https://assets.southwire.com/ImConv...tDescr=Copper Service Entrance SER Cable.spec

 

[brathnach]

$ would always be the main one, but while copper is the better electrical conductor, aluminium is ~ 3x lighter.

J

 

[andyvh1959]

My house was built in 1973, which I believe is after the aluminum wire alloy changes for electrical service. The main SE cables to the 200 amp Load Center are aluminum. Everything else in the house that I have seen or worked on is all copper. Doubt I have anything to be concerned about.

 

[pcmeiners]

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

In NYC when aluminum first was used in homes/businesses ( 1960s?) there was an issue with being brittle over time, breaking anywhere along branch runs, and causing fires .

 

[rburke65]

The issue was the connections where the aluminum and copper were terminated together and caused corrosion as a result of the mixed metals.

 

[neophyte]

$ would always be the main one, but while copper is the better electrical conductor, aluminium is ~ 3x lighter.

J

This is my understanding of why aluminum is used for overhead cables, especially on long runs. The lower weight of aluminum, causes much less line sag, as well as makes installation easier.

As far as the issues with aluminum house wiring,
Aluminum builds up a layer of sluminum oxide on the outside, when exposed to atmospheric oxygen.
Aluminum Oxide is an insulator, which then causes bad conductivity at wire connections, which causes amperage spikes and possible short circuits.
While a tight connection should seal the wire connection, the copper/brass/bronze alloys used for typical electrical connectors and terminals, have a different thermal expansion and contraction rate then the aluminum alloys that were used for wiring, which could then cause gaps in wire connections, causing air to get into the connections, causing oxidation of the bare aluminum wire ends.

 

[PatJ800]

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.

Sorry to drag this back up

I found this in a search and am curious; so you as an electrical engineering firm write into the bid specs for an engineered job to use copper and then give AL as a VE option? Who is asking for this VE option and at what point in the project or does it go to the GC with the initial bid? What kind of savings % are your contractors bidding on your average commercial job for the AL VE? Does the AL require different pipe sizes etc, that offset the conductor savings?

Also curious what kind of work you guys are doing where customers ask for this? Low-density/high density residential? Business commercial? Education? Healthcare?

Thank you very much for the info, I'm always trying to learn and so much I don't know. Thank you