Renovation & Design

ASK THE INSPECTOR: Aluminum wiring requires special plug-in receptacles

QUESTION: My home was built in 1978 or 1979. It has aluminum wiring. Lately, I am noticing sparking in different plugs when I plug something in. Is this something to be concerned about. Thank you. Barb Wild

ANSWER: Sometimes when minor sparking is seen in an electrical receptacle it is a result of a lack of use but may also be a sign of excessive corrosion or damage, especially in homes with aluminum wiring. You're right to be concerned and should hire a licensed electrician to evaluate the offending receptacles, or possibly all of the electrical devices in your home, to ensure safety.

Aluminum wiring installed in homes in our area, mainly from the mid sixties to mid seventies, may provide some unique safety challenges for owners. Because your home was built near the end of the common use of aluminum branch wiring, you may have properly rated receptacles, but this should be checked to make sure.

Aluminum wiring has been problematic in many areas because it is very soft, subject to easier damage than copper, and excess oxidation can cause an increase in fire hazards. For these reasons, special devices have been developed for use with aluminum.

The designation CU/AL was stamped or printed on original electrical devices approved for this use. While these are still acceptable for circuit-breakers and many light switches, duplex receptacles with this rating should be upgraded. Many homes were found to have problems with excessive oxidation, overheating and damage at these receptacles.

For that reason, newer devices with the rating of CO/ALR were developed and are required to be used in these areas. The newer receptacles have fasteners with metals that were more compatible with aluminum, reducing the chance of oxidation and overheating.

To determine if your home has the properly rated CO/ALR units, or outdated and potential dangerous CU/AL, you could remove a few cover plates and inspect the receptacles. For safety, this should be done after the circuit-breaker is shut off at the panel. This can be done by plugging in a radio with the volume turned up, and shutting off breakers until the radio becomes quiet.

Removal of the plastic cover plates with a simple screw driver should reveal the top and bottom tabs of the receptacle, where it is secured it to the metal box. Look for stamped printing of the CO/ALR, normally on the top tab. This may be obscured by old paint, dirt or other debris, but use of a flashlight and a dry rag to clean the surface may help you see the imprint.

If it is not present, or CU/AL is seen there or in another location on the unit, repairs or replacement should be done. You should also look for any obvious soot, stains, scorching, discoloured wiring or melting on the receptacle, wiring or surrounding area. If this is seen, immediately discontinue use of this device and call an electrician for further evaluation and repairs.

If you can see the proper designation stamp on the tab and no physical evidence of damage or overheating is visible ,there may be nothing to worry about. Several other receptacles should be inspected to ensure they are also properly rated and not damaged. The ones most prone to overheating are in high-use locations with appliances that draw considerable current. This is often above the kitchen counter where microwaves, toasters and kettles are used or hair dryers in bathrooms.

If they all seem to be in satisfactory condition, you should replace the covers, re-energize the circuits by switching the breaker to the ON position and monitor for ongoing issues. If there is any visible damage or evidence of overheating, particularly on older CU/AL devices, upgrades will be required.

The solution to damaged receptacles or wiring may range from simple replacement of the receptacles with the properly rated devices to removal and replacement of melted wiring. Installation of CO/ALR receptacles may be quite simple, but the cost of these devices is quite a bit higher than regular ones, so upgrading an entire home may be a moderately priced expense.

Because your home has aluminum wiring, which has been known to be problematic, calling a licensed electrician to check all of your receptacles is a wise move. The results of this inspection will either provide a greater sense of security or lead to repairs that may dramatically improve the safety of your electrical system.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home & Property Inspectors - Manitoba ( Questions can be e-mailed to the address below. Ari can be reached at (204) 291-5358 or check out his website at



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