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My house has aluminum wiring, which from what I understand isn't recommended any more. How do I replace a plug or switch since the new unit only takes copper wiring?

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Wow, I've never heard of aluminium wire being used in a house before. – Matt Jul 7 '13 at 21:45
You've got a fire hazard! The aluminum oxidizes over time, increasing the resistance of the connections. Resistance x current = power (heat) lost at the connection. The connection heats up and cools down, slowly working its way loose and further degrading the connection. At our old place we had arcing inside the main breaker panel at the connections to the aluminum feeder wires due to this! – Technophile Nov 8 at 0:28

8 Answers 8

up vote 16 down vote accepted

There are two ways to do it:

  • Use CO/ALR switches/receptacles: these are specifically designed for aluminum wire. They have "CO/ALR" stamped on them somewhere. When you connect the wire, use a paste like Noalox (box stores sell it).

  • Use a pigtail connection: Sometimes it is not possible to find CO/ALR switches with the function or style you need. You can use a copper wire to connect to the switch itself as usual, and then a #63 wire connector to connect the copper wire to the aluminum one. Here is a picture of a 3-way dimmer switch I installed using this method:

    alt text (apologies for fuzzy picture)

    Note that you do the same thing with switches that have wires coming out of them already (like most dimmer switches do) or any other fixtures.

    enter image description here

To quote from the ESA (Ontario Electrical Safety Authority)'s Notice on Aluminum wiring in residential installations:

Even though not required by the Code, it is recommended that bare ends of solid aluminum conductors be coated with approved joint compound.


  • The Ontario Electrical Safety Code permits the installation of aluminum wiring.
  • Adequate precautions shall be given to the terminations and splicing of aluminum conductors;
  • Aluminum wiring itself is safe if proper connections and terminations are made, without damaging the wire and devices approved for use with aluminum wire are employed.
  • Aluminum wiring is widely used today for larger commercial and industrial feeders. Electrical distribution companies use it widely throughout their distribution systems including the supply service cable to most residences; in fact it may still be used today for interior wiring systems in residential homes as well as other structures.


Aluminum wiring itself is safe and if proper connections and terminations are made without damaging the wire and using approved materials installed in accordance with the Ontario Electrical Safety Code and the manufacturer’s instructions, there should be no problems with the aluminum wiring installation.

In either case:

  • Connect with #63 wire connectors.
  • Use the anti-oxidant paste on the wire and any other connections involving aluminum (apply to the wires before you screw on the connector).
  • Use a wire brush to remove any oxidation before applying paste and making the connection
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Hey @gregmac your picture is no longer available. Are you able to re-upload it? – Steven Jul 7 '13 at 21:49
According to the CPSC (Consumer Product Safety Commission), "CO/ALR devices must be considered, at best, an incomplete repair" that's only intended "as an emergency, temporary repair of a failed aluminum termination." Though less detailed, the answer below by @Jerr seems to be the safest method for dealing with aluminum wiring. See for more information. – kevinmicke Mar 14 at 19:43
Use the oxidation inhibiting paste, but also wire-brush the exposed wires before applying the paste. ;-) – Craig Jul 7 at 20:06
@kevinmicke I find it hard to take the CPSC document too seriously when it doesn't even mention anti-oxidant paste at all. Contrast that to what the ESA says, which I added to my answer. – gregmac Jul 7 at 21:57

Here's what I did in my house, based on internet research and asking my Dad, a construction superintendent.

  1. Buy some wire nuts made for multiple types of wire and some anti-corrosion compound (usually available in the same area of the hardware store).
  2. Take some copper wire and twist it together with the aluminum wire.
  3. Put the compound on the wire and some inside the wire nut.
  4. Twist the wire nut onto the wire twist you made.
  5. Use the new copper end to connect to the new plug/switch.
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Very important safety note for the above: I believe you need to put the corrosion compound on BEFORE you twist the wires together. This prevents bimetallic corrosion between the two different types of wire, which would lead to higher resistance and a fire. Just smearing it on after you've already joined the wires is not enough. – Karl Katzke Aug 15 '11 at 1:14
While that will prevent corrosion, won't you still get the separation caused from the heat generated between the copper and aluminum expanding? – Zach Aug 18 '11 at 1:09
If you need to connect copper to aluminum, do not directly twist copper with aluminum. The two will eat at each other, and resistance and heat will increase. The only way to splice copper to aluminum safely is using a device listed for that use. Others here mentioned a wire nut that you can safely use instead. – Jeremy W. Sherman Jul 13 '12 at 21:48
You should also use a wire brush on the exposed aluminum before applying the rust (oxidation) inhibiting paste. – Craig Jul 7 at 20:14

I am a licensed electrician in Connecticut. My own condo has aluminum wiring, I highly recommend the alum.con connectors because they are homeowner friendly. Two methods are presented:

  1. a special torque screwdriver (recommended)
  2. a set of specific instructions for the number of turns on the copper side/aluminum side.

These connectors are quickly becoming accepted by major insurance companies. Their downside is price: approximately $2.00 each, and figure three per outlet if you choose to do the grounds as well.

Also they are a bit larger than standard wire nuts adding a bit more difficulty for wire and device room in a existing device box. They appear to be code compliant in most cases for cubic inch capacity.

I have installed them in my home and neighbors. The biggest issue with aluminum wiring arc issues are exterior walls that are poorly insulated and major temperature changes occur over the years exaggerating the expansion/contraction issues. Hope this helps.

Do not use the Ideal purple wire nuts; I've seen too many melt downs; it's a bad product.

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I discovered I have the same issue here. My research has found that aluminum wiring is UNSAFE, and you need to be very careful about what you do. The two options are:

  1. Replace the wiring. This is not something that would be safe to do on your own (you really should get a licensed contractor), and looks to cost several thousand dollars (like $8000+ for a 1600 sq ft home).
  2. Use AlumiConn. This stuff is actually approved to be used for aluminum to copper connections (the other pigtails mentioned here are NOT), and you can get a free sample to try it out. There's another thing, called COPALUM, but it's not really something you can DIY. Wikipedia has some good information on this.

I'll update when I actually get my sample AlumiConn connector to see if it's a viable option. The safest option would be to get a licensed electrician to rewire the house with copper, since the aluminum connections are inherently dangerous (and you will probably find other issues, such as bad breakers, 3-wire 240V instead of 4-wire, and a poorly labeled breaker box like I did). I've had receptacles in my house spark and connections melt because of the aluminum, so please take this seriously.

Edit 1: There's also more information about aluminum wiring from the CPSC (PDF) (Consumer Product Safety Commission).

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"since the aluminum connections are inherently dangerous" How so? Isn't the only danger when you mix them with copper or other non-approved components? – Zach Aug 18 '11 at 1:11
You still have the problem of oxidation. When the connection oxidizes, it increases resistance, which ultimately means heat. I'll update my post with a link to the CPSC document on aluminum wiring. – Jerr Aug 20 '11 at 19:46
The main issue with the aluminum conductor is that aluminum expands more than copper when heated. This can cuase loose connections which can lead to arcing at the point of connection. – RSMoser Nov 4 '11 at 16:01
@Zach I know I'm coming along years later here, bu the Jerr is right. Aluminum rust (aluminum oxide) is an effective electrical insulator. It doesn't conduct electricity. So if even a straight aluminum to aluminum connection isn't protected from oxygen, it will oxidize and create resistance and heat, which can lead to a fire. – Craig Jul 7 at 20:10

My parent's house has aluminum wiring. You can either search for CO-ALR switches and plugs which take aluminum wires or get the paste as you said and wire them together. The paste is important, otherwise the wires corrode and start rubbing/sparking .... bad mojo from there.

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Also a good idea to wire-brush the exposed aluminum wire ends before applying the paste. Aluminum oxidizes very rapidly. In fact, if aluminum oxide didn't form an air-tight seal when it forms, you could almost watch an entire chunk of aluminum rust right in front of your eyes. – Craig Jul 7 at 20:08

Just buy the ALR rated outlets and switches. You can pigtail but I don't like that as you now have 2 connections instead of one and you bend the wire more stuffing all that into the box. I have 35 yr old alum wiring. My wiring is in great shape. Replaced several outlets that needed to be replaced. They had the classic alumnimum connection issues. Connected properly there is no problem with aluminum wire. I remember when it came out the industry was publishing all sorts of propaganda to sell ALR as the next big thing. Popular mechanics did a big piece saying we'd never use copper again. Now they are selling $50 "special" cold weld connectors. Its all a big friggin joke and a $ machine. A good connection will remain in place for decades no matter how many hot/cold cycles it goes thru. A bad connection may very well have problems.

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You should probably talk about what a proper connection is. – Chris Cudmore Mar 27 '13 at 13:01
Pigtailing in general is fine. In fact, it's preferable to connecting multiple wires to a device like a receptacle. Aluminum connections that aren't done right can start fires, and there's no getting around the fact that making a proper electrical connection with aluminum is more technical (and thus more prone to mistakes) than with copper. – Craig Jul 7 at 20:13

To my knowledge, this insulated 3 port splice connector is the safest product on the market right now. Unfortunately, I don't know who actually makes it or what it's called- just what it looks like. NSi Industries (Tork) makes something similar (their IPL series), but I'm not sure if they make really small ones like you need.

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/The aluminum to copper splice connector that I use is the AlumiConn 95104 which fits wire from #18 to #10. Remember that aluminum wire is larger than copper for the same capacity current. These connectors are available at Lowes for about $6.50 for a package of 2.

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