Hugh Cairns: All about aluminum wiring

“Having received an increasing number of questions about the safety of aluminum wiring, and in particular, questions from those purchasing a home with aluminum wiring, I have written this fact sheet to clarify aluminum wiring concerns.”- Hugh Cairns, RHI

When was aluminum wiring used in homes?

For over 100 years, the material of choice for residential branch wiring has always been copper, but when the price of copper spiked in the mid 1960’s, aluminum wiring was sometimes used as an economical alternative. By the mid 1970’s, inherent weaknesses were determined in aluminum wiring that led to its disuse.

It may surprise you to learn that there are an estimated 450,000 homes in Canada with aluminum branch wiring.


Is aluminum wiring safe?

Aluminum branch wiring in homes was installed the very same way as copper. Typically, aluminum branch wiring was connected at the electrical panel, and at the other end, to an electrical device or terminal. The behaviour of aluminum wiring at the device or terminal has been the focus of the issue, and not the wire itself. 

When aluminum branch wiring was introduced, the wiring material changed but the same copper devices were used. When electricity flows through either metal, it causes it to expand and contract. Aluminum and copper have different expansion properties. When the two different metals are connected, the differences in the expansion properties can cause the connection to become loose. Loose connections can result in sparking, arcing oxidation and heat buildup, all of which are safety hazards.

Fortunately, the problems associated with aluminum to copper connections are now well understood.

Aluminum wiring

How to tell if you have aluminum wiring?

The only way to tell if you have aluminum wiring is to inspect the electrical branch wiring system. If you’re not comfortable around electricity and wiring then call in a pro. It’s a small investment to have a licensed professional do the work for you.

The first place to look for aluminum wiring is at your electrical service panel. By removing the cover and visually inspecting the exposed end of each wire connected at the panel, look for aluminum coloured wires. You’ll notice that there is a mixture of large and small gauged wires installed in the panel. Larger (thick) gauged wire will be used for feeding the heavy loads, like electric ranges and dryers, while the smaller gauged  (thin) wire will supply electricity to the lower branch lights and wall plugs.

The electrical supply lines that enters our homes is usually aluminum, as is almost the entire power grid.

You may find that copper branch wiring has been installed throughout the home. Alternatively, you may observe the presence of aluminum branch wiring to all, or part of the home.

Large aluminum gauged wiring (220-volt) serving major appliances is considered acceptable in most cases because:

·       Normally there are only two connection points in the circuit

·       These connection points or are of a different design than that found in a household receptacle

·       The wire connection usually is straight without a sharp bend or crimp

·       Major appliances and their currents are more likely installed by qualified professional electricians

·       During the late 80’s, manufacturers made improvements on the aluminum wire itself by adding a small percentage of other performance enhancing metals

Aluminum is an excellent choice for main distribution wiring, but not for lower branch circuit wiring.

Another way to determine the presence of aluminum branch wiring is to inspect the branch wiring sheathing. You may be able to see wires entering the panel or perhaps you can look between open floor joists or up in the attic.

Aluminum wire sheathing made before May 1977 will be marked with

·       The word  ALUMINUM

·       An abbreviation –  ALUM, or AL.


Aluminum wire sheathing made after May 1977 will be marked with

·       The word  ALUMINUM

·       An abbreviation – ALUM, ACM, or ALACM


Aluminum wire sheathing may be marked with the manufacturers’ name:

·       NUAL

·       STABILOY

·       ACM


Items that indicate electrical problems and requiring inspection are:

·       arcing or sparking at an electrical device – unusual sounds such as sizzles or buzzes

·       an item is hotter than it typically should be to touch

·       breakers or fuses continually trip or blow

·       equipment or wire is damaged

·       discoloration of receptacle or light switch cover plates


What can I do if my home has aluminum branch wiring?

If you have lower aluminum branch wiring, the correct way to get started is to have your electrical system assessed by a licensed pro.  

If your aluminum wiring is terminated on devices that are currently approved for use then most likely all that needs to be done is for the electrician to inspect all connections and possibly apply some anti-oxidant. Still, this is considered a temporary solution.

If the aluminum wire is not terminated at properly approved devices, then one you may elect to choose one of the following options:

·       Replace all devices to the current standard. This is considered a temporary solution.

·       The correct and lasting solution is to eliminate the aluminum wiring in its entirety.

Short-term fixes are least effective as they are only temporary and need to be checked every few years for further system deterioration. Doing the math, and using the short term or Band-Aid fixes, don’t return your investment as effectively as full replacement.

Aluminum wiring

Aluminum wiring and age

Now that lower branch aluminum wiring is more than 40 years old, it’s long overdue for and inspection if you haven’t had one.

While it might be tempting to believe that a home with aluminum wiring is safe because the wiring hasn’t caused a problem for 30 or 40 years, that is a risky misconception. The longer aluminum wiring connections are uninspected and allowed to deteriorate, the more likely a problem will occur.

How to replace aluminum wiring

You can do some of the work yourself or you can hire a pro. Sure, it’s possible for a determined and skilled homeowner to pull the wiring, but hiring a pro is really the way to go. The experts are experienced in minimizing drywall damage and carefully fish in new wires. Seek out a specialist with years of experience doing just this for the best results.

Aluminum wiring

Cost for replacing aluminum branch wiring

With over 450,000 homes in Canada with aluminum branch wiring it would be convenient to have a simple formula for pricing out the cost of replacing aluminum branch wiring. Since there are so many variables in construction techniques a simple formula is impossible to devise.

Hugh Cairns aluminum wiring replacement tip…..The cost of replacing or repairing aluminum branch wiring is best estimated by the person or company doing the work. You’ll need to consider materials, labour and interior access and remediation. Replacing aluminum branch wiring is almost always invasive. There are plenty of solid techniques that you or your contractor can use to minimize the remediation process.

The cost of replacing your aluminum wiring in your electrical system can be likened to the cost of several routine home maintenance items such as re-flooring your home for putting on new roof shingles. If you are in the position to re-wire the home, and you weren’t prepared, it’s an unfortunate position to be in. But it really is similar to other maintenance items, perhaps one you didn’t expect.

Replacing aluminum wiring is a good investment in your home. You will realize peace-of-mind and increased value to your home.

Aluminum wiring

Aluminum wiring and house insurance

Homeowners’ insurance is a necessity, something every property owner should have. If you have a mortgage, your lender will require coverage — and if your home is mortgage-free you should have coverage anyway.

The usage of aluminum wiring has raised concerns within the home insurance industry regarding their risk exposure. Not surprisingly, the residential insurance industry is approaching the issue in much the same way that they do with other residential risk categories. As a result, some homeowners are finding insurance companies are offering varying opinions and different reactions to underwriting aluminum wiring coverage when it comes to renewal or new policy time.

Clients are experiencing a full range of responses regarding the presence of aluminum wiring and the home’s insurability. In some cases aluminum wiring is treated as trivial, in others, aluminum wiring has resulted in higher insurance premiums. Some clients have reported that the deductible for this condition exceeds the cost of replacing the entire lower branch wiring system. In some cases, requests for insurance have been denied by a particular insurer leaving clients to scramble for an insurer that will underwrite for them.

If you are presently insured, electrical failures of all sorts is typically covered by most policies. When a home experiences an insurance claim the underwriter regularly adds the claim to a database associated with the property. Should you experience an aluminum wiring insurance claim (or multiple claims) your insurer may decide to increase your premium, your deductible, or worse yet, may not renew your policy. Remember, this action can happen as a result of any casualty, such as fire or weather damage.

Aluminum wiring and buying a house

The discussion of aluminum wiring and its relation to insurance underwriting often occurs well ahead of purchase offers. Should the presence of aluminum wiring be determined in the home that you intend to purchase, you should initiate dialogue with your insurer immediately. The presence of aluminum wiring may affect the underwriting of the home and your acceptance of the terms offered to you by your insurer.

If you have previously bought a house or you are a first time home buyer, you probably know that the process of purchasing a home is not like buying anything else. Once your purchase a house, there is usually no option to return or exchange it if you don’t like it.

Because of the finality of buying a home, usually there are several standard optional conditions that must be met before the deal can be closed. These conditions include subjects like financing arrangements, home inspections and insurance. Contingencies are considered a matter of course in real estate transactions and their presence within a purchase agreement is designed to protect the parties involved.

Aluminum wiring and home inspections

Virtually all homes have some cosmetic and routine functional defects that can be corrected easily. When buying a home, your home inspector should help you prioritize what to repair in the short term and what you can leave for later. A home inspection will not determine if an aluminum wiring system is about to fail, but it can look for conditions that promote its reliability and longevity.

Most home inspection clients find that it is prudent to share the report and findings regarding the home with their realtor or designated representative because of its significance in negotiating the agreement of purchase and sale. When the presence of aluminum wiring is determined, the condition should be discussed with your insurer and realtor for advice.