Alumimum Wiring


Old 03-28-20, 10:40 AM
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Alumimum Wiring

Re-question; My home built in 1949 has Aluminum Wiring.( I am the 3rd owner) There has clearly been some re-wiring done that are incorrect and i have been working on correcting them. Short of spending upwards $10k for re-wire the whole house with a new breaker box, i am doing room by room remodel. All the rooms had the plug outlets replaced with 3 prong plugs and are clearly not Grounded. Some still have to orginal Metal boxes, while some were replaced with plastic boxes, again none are grounded. I did find places where New Romex wiring were used and spliced in, the ground copper wire were just cut flush and not attached anywhere. Where the Old Alumimum Wire were spliced using tape i replaced with the AL/CU caps. "My question is Should i replace the Plastic back to Metal boxes and reground the outlets where i can?" (Future plan is to have the Breaker box upgrade to a 200 amp box with ground, but thats another question for another day)
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Old 03-28-20, 10:53 AM
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You're asking if we recommend patching what you have.
My recommendation is no. Replace it while you have the rooms open.

I didn't think that aluminum wiring was used in homes in 1949.
Are you describing wiring in rooms or larger wiring to appliances ?

Are you sure that's not silver or tin plated copper wire ?
When you cut the wire..... look carefully at the end.
Old 03-28-20, 10:55 AM
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I thought that aluminum wiring didn't start until the 60s. Are you sure that it is aluminum and not tinned copper?
Old 03-28-20, 11:02 AM
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No these are Aluminum Wiring. Original to 1949. Basic wall outlets. The outlets for any major appliance were not switched out, a 3 prong adapter is used in those place. And Yes i am Sure these are Aluminum Wires, they were used in homes in this area, until no longer allowed. You do not answer the question No What? I am not tearing out whole walls, just fixing damaged sections and painting. My concern is the "Grounding" I have seen where the splicing is done from Aluminum to Copper using AL/CU caps and grounded to "Metal" boxes. Do i switch out the Plastic back to Metal and Ground? That sounds more safe.
Old 03-28-20, 11:11 AM
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I am pretty sure on the wiring. 2 wires, 1 white, 1 black, No Ground. So with new fixtures that have Grounds and where Romex has been spliced in if the Box is Plastic how do I Ground them?
Old 03-28-20, 11:45 AM
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Plastic boxes do not need to be grounded. They are non-conductive.

I would like to see pictures of aluminum wiring from the 1940s.
Old 03-28-20, 01:22 PM
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Aluminum wire was used in homes at the end of WWII because of a shortage of copper and it was expensive if you could get it, but I am not sure for how many years. This is something I wasn't aware of either till I met Dr. Jesse Aronstein at a conference and this was part of his presentation. I have worked in many of those older homes in years past and never found any to be wired with aluminum wire, but also never had a reason to doubt Dr. Aronstein. The only place I have ever found any documentation of this is from a August 1987 copy of Popular Mechanics. If you scroll down to page 107 you can read it for yourself.

Where the Old Alumimum Wire were spliced using tape i replaced with the AL/CU caps.
If you used the purple #65 Ideal Twister wire connectors you now have a decent temporary connection, but definitely not a permanent solution. Those Ideal purple wire nuts are not approved for connecting aluminum to copper wire by the US Consumer Product Safety Commission and have never been tested by UL. NO twist-on connector is approved for aluminum to copper connections. I would advise replacing them with the only DIY approved connector, the AlumiConn Connector.

Here is a publication you should get familiar with if you really do have aluminum wiring, Publication 516 from CPSC. I would like to see a picture of a cross section of a piece of your aluminum wire. If the wire has a copper core you just have tinned copper wiring which was very common in 1949.

Old 03-28-20, 07:47 PM
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No real difference between metal and plastic boxes. People have preferences, but no real difference when you're rewiring. I tend to prefer plastic as they are easier to install and don't require grounding the box.

If it were my house, I'd rewire one circuit at a time with newer NM-B (Romex). For the runs that have already been redone, it may take some work to figure out if they can be salvaged or needs to be replaced and redone correctly.
Old 03-29-20, 05:42 AM
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Hi, so if it is Al. then the conductor size for the 15 Amp circuits should be #12.
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