Aluminum wiring was used in Western Canada in the late 1960’s through to the mid 1970’s. If purchasing an older home today, a lot of people are scarred away by the existence of aluminum wiring because of the potential threat of fire. Let me put the record straight.
There is nothing wrong with Aluminum wire.
The problem comes when an aluminum wire is compressed under the screw, on the side of a switch or receptacle for example. This problem is called “Cold Flow.”
When electrical current flows through an aluminum conductor, it heats up. This is one of it’s characteristics. With the generation of heat comes expansion and of course when it cools you have contraction. This happens on a very small scale but over time, the action may loosen the pressure of the screw on the aluminum. What happens next is cold flow.
The current still tries to go through the now loose connection and arcing happens. With arcing, the screw starts to heat up and eventually the plastic of the device starts to melt and soon, as we have found out, fires occur.
In the last while, insurance underwriters have been increasingly concerned with the fact that aluminum wiring exists in homes. They have started to refuse insurance coverage, demanded corrections be implemented, or at least, like some, are requesting a inspection and report by a qualified electrician or inspector.
- Alumicon, a connector with set screws.
- Copalum, a compression type of connector.
- CO/ALR, Aluminum compatible devices, (receptacles not legal in Canada).
- Pig Tailing (shown to the left).
Our company, Robart Electrical Services Ltd, does on average 50 aluminum wiring upgrades a year. In my experience, after extensive investigation, the only method I feel comfortable with is Pig Tailing.
Pig Tailing is not just connection a piece of copper wire to an existing aluminum conductor. There are additional precautions that must be met in order to meet the requirement that make this procedure safe.
One of the most important steps is that the exposed aluminum and copper must be coated with a non oxidizing compound then twisted together before the approved marett is put on.
This photo to the right is a result of what“Uncle Dave” pigtailed 2 weeks earlier. I found this in a switch box of a 1972 house that clients wanted to purchase. Uncle Dave did not twist the wires together before he installed the marett.
Please see “Aluminum Wiring – Is It Safe?” in our Documents and Downloads section of this web site for more detailed findings relating to the above mentioned methods!
Robart Group of Companies