Aluminum Wire - What's all the hype?

Aluminum wiring

I can always tell when home sales are up or insurance policies are due; I get calls for aluminum (AL) wire inspections.  One of the most important things during my AL wire inspection is educating the potential buyer or the current homeowner on the facts about AL wire and helping them sort out the hyperbole "that their house is going to burn down" because it has AL wring or some other ridiculous statement.

I will focus on Canada, but pretty much any residential construction in North America from the late 1960s into the early 1980s used AL wire.  The change to AL wire was prompted by the rising price of copper (CU) wire.  With the change to AL wire, there were some minor changes to the electrical code but basically the installation methods were the same.  It is also fair to note that AL is still used in North America as feeder conductors (the wires that feed your house and panel) and its use is not prohibited in the Canadian Electrical Code (CEC).

So that brings me to my first bit of hype about AL wiring - installation of AL wire is inferior.  This simply is not the case.  In a majority of inspections that I have done, the installation was code compliant for the code at that time.  Yes code requirements have changed, but the basics of the AL installations are still the same as today.  You still need boxes, clamps, connectors, etc today that you needed for AL wire back in the 70's.  Chances are that the installation was inspected and passed so the basic installation is likely still reliable today.

As the number of AL installations increased, so did the negative issues with it; but again not from the wire itself, but from what we were doing with it and to it.  The main issue with AL wiring is that the wrong devices were connected to it or connections were done incorrectly.  Wrong meaning, CU rated devices and connectors that were incompatible with AL wiring were being used. Installers at the time were learning how to work with this new product and products and methods were not necessarily up-to-date.

Here is my next bit of hype - upgrade all the devices to CU and the installation will be safer.  In fact that makes the installation unsafe.  Where this comes into play is that all the newer devices like Decora® or all the coloured switches and receptacles are only rated for CU wire.  The only style available for AL is the older style "face" (NEMA 5-15).  So people are forced to make alterations to their system so they can use a modern style receptacles and switches.

The key to all of this is making sure you have a safe transition from AL to CU so you can use the more modern receptacles and switches or be able to replace worn devices.  If you are happy with the "face" style receptacle and the classical toggle switch, then the best option is to find a device that is CU/AL or CO/ALR rated.  If you have one of those, it is generally a "one for one swap" and is the easiest and most cost effective replacement solution.  If you want other options, then you need to look at what we call "pigtailing".  There are a few ways to do that, but essentially you will use an AL rated solderless connector of some sort that mechanically connects a short piece of CU wire to the AL wire.  You will also need an antioxidant paste if the connector does not have it in it already (Rule 12-118(2)).

Another bit of hype - I have to rewire my entire house because of AL wire.  So now we know the process on how to mitigate AL wire connections when necessary, where is the hidden part?  The hidden part to all of this "pigtailing" comes with the size of box that is used.  By using solderless connectors you will lose valuable space inside that device box.  That space inside the box is there to give the wires room so they don't get damaged when the device is installed as well as it also acts as cooling; giving a space for the heat to dissipate.  I am not going to go into how to calculate box fill (Rule 12-3034), but it is something that you may have to deal with if you want to go the "pigtalling" route.  Going to each device and making the correct connections and perhaps replacing a few boxes here and there is very labour intensive.  While replacing a receptacle or switch is what I would consider "homeowner maintenance", doing a complete "pigtailing" is not necessarily a DIY undertaking.

So straight to the facts - Is AL wire safe?  Yes it is, but there are a few caveats:

  • the AL wire must be the original installation that was code compliant;
  • the installation should not have been modified at all;
  • only AL rated devices have been used;
  • there is not any signs of heating or other stress on the cables; and
  • regular maintenance was performed to ensure optimal performance.

If you are not sure on any of the above, then it is best to call a licenced professional and arrange to have your AL wire inspected.

About the Author

John Kuehnl-Cadwell is a Master Electrician and an owner of Datawise Solutions Inc., an electrical contracting company located in Ontario. He has been licenced as a Journeyman Electrician since 1992.

Posted by: John Kuehnl-Cadwell
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