03 Mar 2017

A closer look at Electrical Wiring

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With the spring real estate market heating up, questions and concerns about aluminum wiring are common with those looking to buy or sell a residential property.

Aluminum branch wiring was used during the 1960s and 1970s in many homes for the wiring of receptacles, switches and other devices. Aluminum does not conduct electricity as efficiently as copper and creates more resistance and heat.

Single strand branch aluminum wiring has been implicated in a number of house fires. The cause of these fires is not normally the aluminum wire itself rather they are the result of improper connections.

Aluminum wiring also expands and contracts more than copper, thus there is a tendency for the connections to become loose at the devices (switches, outlets and breakers) and junction boxes. Oxidation will build up between the loose connections, causing an increase in the amount of heat generated, which can then pose a potential fire hazard.

Do not replace devices with “copper only rated” devices because they also could be a fire hazard. There are copper/aluminum rated devices available but they’re much more expensive than the standard copper only rated devices.

In the interest of safety, when it comes to aluminum wire, you need to contact a licensed electrician if:

  • Outlets and switch cover plates are unusually warm or warped
  • Smoke or sparks are coming from receptacles and switches
  • There are strange odours in the area of receptacles and switches
  • You have untraceable problems with plug-in lights and appliances

Lights periodically flicker.

Many individuals and insurance companies believe aluminum wiring should be removed and replaced with copper. It should be mentioned that this is not always necessary because there are approved or recognized methods for making these systems safe.

If single strand aluminum wire is present, (No. 12 or No. 10 general purpose branch wiring) it is important to install or verify proper connections of all devices and terminals throughout the house. Copper wire ends, known as “pigtails,” can be installed at all terminals. Standard wire nuts are not approved for pig tailing and should be replaced if present as they pose a fire hazard. Special wire nuts approved for aluminum and copper connections must be used.

Care to be taken with aluminum wiring:

  • Do not over-fuse aluminum wiring. The AWG (American Wire Gauge) rating of No. 12 aluminum wiring is equivalent to No. 14 copper wiring. Both are rated for 15 amps, so use only the t5 amp rated glass fuse, cartridge fuse or breaker for aluminum wiring stamped either 12/2 or 12/3.
  • Copper and aluminum should never be connected together except using special anti-oxidant paste and crimped with approved clamp connectors. If you use twist-on connectors (wire-nuts or marrets), make sure they are approved for use with aluminum wiring.
  • When purchasing replacement receptacles, switches or fixtures, ensure that they are compatible for aluminum wiring. Typically, receptacles that are approved for aluminum wiring will be stamped CO/ALR, CU-AL or AL-CU indicating they can be used for both copper and aluminum. Newer Decor switches and outlets (the new designer look flat outlets and switches) are not aluminum rated.
  • Do not use receptacles stamped with AL and a line through it. These receptacles are incompatible with aluminum wiring.

As part of your preventive maintenance plan for the home, check switches and receptacles by removing the cover plates and visually inspecting the wires for any signs of scorching, looseness, heat and odour.

Aluminum wiring is not DIY-friendly. If you suspect anything unusual, have a licensed electrician work on circuits with aluminum wiring.

If you own a home with aluminum wire you should have a licensed electrician check all connections every few years to ensure they are tight and not oxidized.

If you’re considering purchasing a home that has aluminum wiring, some insurance companies will ask for an ESA (Electrical Safety Authority) inspection of the home, some will charge a premium to insure the home, or some may even require that all connections be aluminum to copper pigtailed, the cost of which may be very expensive, before they will insure the home.

Author: Rob Parker  

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