Recognizing the Dangers of Hazardous Residential Aluminum Wiring

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Even though aluminum wiring is in many Ottawa homes, there are many dangers that you need to be made aware of.  Call Ring Electric at (613) 299-8239 to book a free quote to ensure the safety of your home!

Substandard Wiring Poses a Fire Hazard

Why does aluminum pose such a fire hazard? For one thing, aluminum tends to expand which compromises the sheathing and may cause connection screws to loosen up over time. Aluminum has a coefficient of expansion in inches per degree Fahrenheit of 0.0000123 – 0.0000129, where copper is rated at just 0.0000093. That’s a huge difference and reason for concern.

Another serious problem is the incompatibility between aluminum and the metals used in connections, junction boxes, electric switches, etc. This causes a condition known as micro-fretting. This means a surface oxide will form which can lead to arcing and overheating. According to, “The connections can become hot enough to start a fire without ever tripping a circuit breaker.”

The U.S. Consumer Product Safety Commission (CPSC) states that, “homes wired with aluminum wire manufactured before 1972 are 55 times more likely to have one or more connections that reach “Fire Hazard Conditions” than are homes wired with copper.”

Tips to Indicate the Use of Aluminum Wiring

Any repair or opening of electrical circuits should be done by a competent person, notably a licensed electrician when the local electrical building code requires it.

There are a number of clues, other than just knowing that the home was built from the mid-60s to the early 70s. The CPSC specifically notes warm electrical switch or receptacle face plates, flickering lights when the bulb is in otherwise good condition, and the odor of melting or burning plastic.

Sometimes it’s easy to identify just by seeing the word “aluminum” written on the sheathing. Another good spot to look is in the circuit breaker box where the sheathing has been stripped to make the electrical connection.

Finally, if all the wiring is 12-gauge and there is no 14-gauge, this is a red flag. The reason is that if aluminum is used, it must be one gauge larger than copper for a given circuit. This is no guarantee but is a strong indication. The gauge should by embossed on the sheathing.

Aluminum was commonly used in place of copper wiring from the mid-60s to the early 70s. Once it was exposed as a fire hazard, its use was discontinued.

However, it should be noted that there are a few situations where it still got the green light for use. Usually this applies to circuits which are dedicated to a single purpose, such as service entrance wiring, electric range circuits, and 240 V HVAC circuits.

The primary two reasons the aluminum substitution was made was because it’s cheaper than copper and it hadn’t yet been outlawed. This situation is similar to the current issue of toxic Chinese drywall used in some southern states; some building contractors are always looking for ways to cut corners financially.

Anyone planning to buy a home with this wiring should be aware of this issue because some insurance companies charge higher homeowners insurance policy rates or even deny coverage.

4 Comments Add yours

  1. seewel says:

    Aluminum wire gets cheaper but always use copper wire for house wiring to avoid any fire hazard due to short circuit. Always use quality cables for house wiring

  2. We should be very choosy when it comes to electrical supplies. Substandard products possess a great possibility for electrical errors.

  3. Mark Clair says:

    I don’t agree to a complete extent seewel because I have done aluminium wiring at my home. It never showed any danger till now. I don’t know whether it is the same opinion with all. And it is always great to choose aluminium wiring because it can save you a lot of money.

  4. Melissa J Young says:

    Aluminum wire is much cheaper than copper wire. If you think of financial disasters, then aluminum wire could save you a lot money at the end. But it causes fire hazards easily. And one suggestion to you all is that always hire some licensed electricians when it comes about wiring. ‘The Shock Doctors’ at Orillia is the one which I prefer.

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