Is Aluminum Wiring Dangerous?

By Scott Sidler

is aluminum wiring dangerousIf your house was built from 1965-1973, you may be one of the “lucky” folks with early aluminum wiring. Thanks to spiking copper prices in the 1960s, builders stared looking for less expensive materials to use for wiring houses and aluminum seemed to fit the bill.

In just a few short years, issues began showing up with this metal being used as the main wiring material in residential construction and it wasn’t long before the industry realized it needed to make some serious changes to the way they used aluminum wiring.

In the early 1970s, manufacturers changed to a superior quality alloy for aluminum wiring better suited to use for electrical work, but by then, it had gotten such a bad rap as being dangerous that the pubic wanted no part of aluminum wiring. It is still allowed in most local building codes, but rarely used.

Problems With Aluminum Wiring

According to the Consumer Product Safety Commission (CPSC), “Homes wired with aluminum wire manufactured before 1972 [before the upgraded alloy] are 55 times more likely to have one or more connections reach “Fire Hazard Conditions” than is a home wired with copper.” That’s crazy!

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Aluminum is not as good of a conductor of electricity as copper, and so larger diameter wires were needed and it generated more heat than copper. Excess heat caused home fires and that’s why people got so scared of aluminum wiring.

Below I’ve listed some of the issues with aluminum for use in electrical applications:

  • Higher electrical resistance: Compared to copper, aluminum has a higher electrical resistance, which means that for the same current to flow through the wires, you need larger wires and those wires will generate more heat because of the resistance.
  • Less Ductility: Once again compared to copper, aluminum is a more brittle metal that does not stand up the constant bending and stretching common in electrical work. As it is worked more and more, it damages the metal, causing even more electrical resistance.
  • Galvanic corrosion:  Most metals suffer from some sort of galvanic corrosion when they are joined with dissimilar metals. Since most receptacles and switches are made to accommodate copper wiring, one of the biggest dangers with aluminum wiring is when you (or past occupants) have upgraded old outlets to new ones that are not compatible with the aluminum wiring. This is one of the biggest causes of fires, so if you suspect that you have aluminum wiring, check that your new outlets or switches are designed specifically for aluminum wiring.
  • Oxidation: Every metal rusts, even aluminum. Copper rusts and turns green, but that’s ok because copper oxide (rust) has a low electrical resistance. Aluminum oxide has a very high electrical resistance, so it creates yet more heat and potential connection problems.
  • Expansion and contraction: When an electrical current is run through aluminum wires, the additional heat causes the metal to expand and contract more than copper wires, which can cause loose connections. For this reason, aluminum wires are never suggested to be installed into a receptacle with the push-in attachments but rather always be wrapped around the screw and tightened down carefully. The stab-in or push-in applications can wiggle themselves loose over time, causing dangerous arc situations.

Fixes for Aluminum Wiring

While expensive and intrusive, rewiring your house with copper will of course resolve your issues to the point you’ll never have to worry about them again. But there may be some better and more cost effective options below to keep your house safe if you do have aluminum wiring from the danger period of 1965-1973.

No Push-In Connections

Like I talked about above these type of connections should be avoided at all costs when it comes to aluminum wiring. Always attached receptacles, switches, or any other fixtures by wrapping the wire around the screw and tightening it down. This will ensure safer connections throughout the house.

Special Connectors

Since the biggest issue with aluminum wiring is at connections, there were special connector designs for aluminum wiring. Don’t just go to the hardware store and pick up a standard outlet and think you can safely install it. It must be marked specifically that it is safe for aluminum. Below is a list of items that are safe for aluminum wiring. If in doubt, ask one of the salespeople at the store to confirm that your choice is indeed made to work safely with aluminum wiring.

  • Small receptacles marked CO/ALR or AL-CU
  • Large receptacles (> 20 amps) marked AL-CU or CU-AL
  • Switches marked CO/ALR
  • Wire nuts marked AL-CU or CU-AL
  • Electrical panels and breakers marked AL-CU or CU-AL

What About Insurance?

A lot of folks have trouble finding an insurance company that will insure a house with aluminum wiring. If that is your situation, then you may have to do some serious shopping around. Some companies ask and others don’t ask. My advice would be that if they don’t ask, then you don’t tell.

You can find insurance companies that will insure your house, but just like a lot of old houses, some companies will write you off as undesirable. Don’t get discouraged, just keep looking.

If you have aluminum wiring, I don’t think you need to have it replaced, but you definitely need to take some extra precautions to keep your home safe.

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