Residential: Aluminium wiring

[HamburgerHelper]

I looking at maybe buying a house that was built in the early 60s and it has aluminium wiring. The disclosure form makes mention that something was done with connectors. I think this is for the connection by the outlets but I don't know for sure. How much of a red flag is this? I am not really a hot on the idea of aluminium wiring with it being old and would not meet present day NEC requirements with it not being AA-8000 alloy.

 

[Mbrooke]

The blunt truth is the original alloy that was used in residential 12 and 10 gauge AL NM was never intended for building wiring. It was based directly on alloys used in over head utility wire where splicing is a whole other animal. As a result the AL metal was completely unsuitable for typical screw terminals and splices found in building wiring practices, ie it would continue to "flow" once tightened and expand and contract more than copper.

The very last AL NM cable made before being discontinued had an upgraded alloy intended for indoor wiring, but by then it was to late, that black eye was given.


About the only good "fix" for AL wiring are copalum crimp connectors. Purple wire nuts are frequently said to fail- and other methods are not 100% certain.


Personally, I would rip it all out and replace it with copper. In 2017 we can stop every electrical anomaly- that is outside of a glowing connection. A high resistance connection can glow red hot and ignite building material without ever tripping a breaker, GFCI or AFCI.

 

[waross]

The fix was to connect copper pig-tails to the aluminium and connect the copper pig-tails to the screw terminals.
Some wire nuts are a solid spiral.
The better wire nuts are a spring that is able to expand over the wires. The resilient spring type with a small dab of Penetrox is the best fix.
I would just walk away unless the price justifies stripping the walls, replacing all the aluminium and then recovering the walls.

Bill
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"Why not the best?"
Jimmy Carter

 

[MikeHalloran]

I ask brokers to not even bother showing me houses with aluminum wiring.

Aluminum wiring was marketed hard to contractors doing developments, so if you find one house with it, any nearby similar houses probably also have it.

The copper pigtails installed to compensate are now decades old, so I wouldn't trust them either.

If I really liked a particular house, I'd insist that it be rewired with copper before moving in.

<The 220V range wiring in my house is aluminum. The A/C|heater wiring is copper. I'm not sure about the dryer.>



Mike Halloran
Pembroke Pines, FL, USA

 

[Skogsgurra]

Did a job in former GDR back in the seventies. All cables were Al. Down to control wiring in 24 V circuits. A disaster. New problems seemed to be born every night. Had to go back home, made them redo the control wiring with Cu and then - after around one year - go back to finish the job.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

When it is time to sell, prospective buyers may be asking the same questions and demanding that the price be discounted.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[stevenal]

Aluminum wire is allowed by NEC, look it up. The connections/devices must be listed for the purpose. In addition to pig-tailing, another fix is to replace the devices with CO/ALR rated ones. Some of the pig-tailing fixes turned out to be problematic, so I would get an electrician to inspect to see which method was used.

 

[HamburgerHelper]

I know that it is allowed. In Mike Holt's forums, there isn't much disparaging that is said about the newer alloys. I don't know what alloy of aluminium is in the house but I would have strong suspicions that whatever is there is the old alloy that was put in when the house was constructed. Any wiring change would be to put copper in. Only recently I would guess has copper prices have come up enough for aluminium wire to re-enter the conversation.

edit: I was still thinking that copper prices were near they were in 2011.

 

[Mbrooke]

The newer alloys found in today's AL are light years ahead and intended to work with listed connectors and terminals found in building wiring. Id say something like 90% of the homes in the US have aluminum for the service entrance, stove and electric furnace where present. This multi stranded conductor is fine and of no issue.

Considering that the improved version of single stranded aluminum came toward the end of the 12 and 10 AWG AL NM fiasco there is a good chance that the wiring found in your potential home is of the old alloy.

Fortunately you would be correct. Copper price has fallen significantly. 250 feet of NM has now dropped to $38 per role where in 2011 it was somewhere around $120 when I had to add a new circuit.

https://www.lowes.com/pd/Southwire-Romex-SIMpull-250-ft-14-2-Non-Metallic-Wire-By-the-Roll/1193437

 

[Mbrooke]

Also of note, new wiring will have another advantage: it is rated 90*C as apposed to the old 60*C. This is normally irrelevant, however many flush mount fixtures mandate 90*C building wire.

 

[GroovyGuy]

Howdy HH,
I wouldn't buy a house with 1960's aluminum wiring, unless I was prepared to replace every last piece of it with copper.
GG
BTW. I have no issues with modern aluminum conductors, and have recommended this to many of my industrial clients.

BTW again. My (1979) house has all copper wiring except for the incoming cable from the meter to my panelboard (which is the old crappy aluminum). Guess what? The termination to my main CB went bad (cold flow?), and melted the CB. I'm surprised that I did not have a fire. I do regular thermal scans now, so far so good.

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)