March 20, 2015 in Electrical, Technical

The True Story Behind Aluminum Wiring – Part Two

In Part One, we took a look at the difference between copper and aluminum wiring, the initial issues with aluminum wiring, and how inspectors can benefit from home inspector training to fully understand issues like this to better serve their clients. In this part, we will continue by looking at the requirements for aluminum wiring, a little bit of its history, insurance information, and what to do if you have aluminum wiring in your home.

First, let’s take a look at a few of the requirements put in place for aluminum wiring.

Push-In Not Allowed

The authorities found that aluminum performs better with screw type connections, where the wire was looped around a screw and held in place by the head of the screw, rather than with the “push-in” type terminations on some devices, sometimes referred to as ‘quick wire’, ‘dagger’, or ‘bayonet’ terminations. Push-in type terminations are not permitted with aluminum wiring.

Joint Compound/Anti-Oxidant Grease

Stranded aluminum wires need a special joint compound that is electrically conductive and prevents rust. The stranded conductors are used on larger cables (8 gauge and up), typically used for large appliances like stoves and ovens. It is agreed that joint compound is a good practice on all aluminum wiring, but the compound is generally not required on solid conductors.

A Better Alloy

In the early 1970s, the alloy used for aluminum wiring was changed to a superior quality wire much better suited to use for electrical work.

The Irony of Improvement

These changes improved the performance of aluminum wiring significantly. However, by the time the aluminum wiring issues were identified and improved, aluminum had received enough bad publicity that it became unmarketable. By the late 1970s, it was no longer used by most builders, although it is still approved and less expensive than copper. Most manufacturers have stopped making solid strand aluminum conductors, although multi-strand conductors for larger appliances and service entrances are still widely used.

The Insurance Question

The home insurance world became aware of the issues around aluminum wiring, and some insurance companies refuse to insure homes with aluminum. Others require a certificate from a licensed electrician or the electrical authority. Some say these decisions were made on conservative underwriting criteria rather than actual loss experience.

Is a Retrofit or Replacement Required?

There were a lot of homes built with aluminum wiring, and a lot of older homes that were updated with aluminum during the 1960s and 70s. What about all these homes that still have aluminum wiring? The electrical authority in Ontario, Canada says, “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.”

Home inspectors who identify aluminum wiring in homes should look for evidence of problems including flickering lights, warm cover plates, discolouration, and melted insulation. Inspectors should recommend an electrical audit of all the connections in the home performed by specialists. The authority in our area does not require that devices be replaced with aluminum-approved devices if no problems are identified.

Homeowners who have aluminum wiring should have an electrical audit performed to ensure their home is safe.


Aluminum wiring in homes has had problems, and significant improvements have been made. Neither authorities nor electrical specialists recommend rewiring a house with aluminum. All connections should be inspected and replaced or improved as necessary—there is no evidence that suggests this has to be done on a regular basis.