In the late 1960′s and early 1970′s copper prices rose and contractors/electricians switched from copper to lower costing aluminum wiring. Although no longer common for distribution circuits, aluminum wiring is still used today in certain applications. For example, 240 volt circuits for stoves and dryers. It sometimes is used on the main service entrance wire from the road to the house. Concerns with this type of wiring have arisen, for example, when aluminum wire is connected to devices (eg. receptacles, light fixtures) which were not designed for aluminum, or, when aluminum and copper wires are attached. In these cases a reaction can occur causing the connections to fail, perhaps become disconnected, and/or, potentially overheat, spark and catch fire. Symptoms of this can sometimes be seen in the discolouration of receptacles, flickering lights, or the smell of hot plastic insulation. The conductivity of aluminum is not as good as copper so a different, thicker, gauge wire must used. For example, today the most common copper wire size is 14 gauge. The comparable aluminum wire size used was 12 gauge. In their most recent 1997 Safety Notice, Ontario Hydro states: “Aluminum wiring in residential installations will operate as safely as any other type of wiring if the proper materials are used and it is installed as per the manufacturer’s instructions and the Ontario Hydro Electrical Safety Code.” Special care must be taken to ensure, for example, that connections are made to receptacles that are suitable for aluminum wiring. Further, where aluminum and copper wires are connected that proper paste/flux, and/or, the appropriate wire connectors, are used. Regardless of the wiring type used, no circuits should overloaded or over fused. What do you do if you suspect a problem? Have a qualified electrician check: 1) Terminations at devices without removing or disturbing them. 2) Cut back any damaged aluminum conductors and join these to a copper tail using a connector approved for use with aluminum. These connectors are coloured either brown or purple, depending on the manufacturer. The copper tail is then terminated at the terminal screws of an ordinary device (which includes approved receptacles, etc.). Or, cut back any damaged aluminum conductors and re-terminate at a new device bearing the appropriate marking.

Only devices bearing the mark CO/ALR are currently approved for use with aluminum wiring. 3) Panel board terminations for signs of overheating. 4) Fuses present for heavy loads are temperature sensitive type (D or P). If a home has aluminum wiring and you suspect problems may exist further professional advice from a qualified electrician, experienced in repairing aluminum wiring concerns, is recommended.

If youre living in a house that was built between the years 1965 to 1973, theres a good chance your home is at increased risk for electrical fires if it has aluminum house wiring. During that period, about 1.5 million homes were wired with aluminum wiring because copper wire was too expensive. Unfortunately, this older aluminum house wiring proved to be a poor substitute for copper. Research conducted by the U.S. Consumer Product Safety Commission shows that homes wired with aluminum wire manufactured before 1972 are 55 times more likely to have one or more connections reach “Fire Hazard Conditions” than a home wired with copper.

After 1973, copper once again become the predominant wire used in new house construction, renovations and rewiring. For those homes that have aluminum wiring, a few simple steps can help prevent some of the potential hazards. The Leviton Institute recommends that homeowners consider calling in a qualified electrician to inspect all the switches and receptacles in their homes and, if necessary, replace them with devices made specifically for aluminum wiring. These devices carry the designation of CO/ALR, which stands for copper/aluminum. Underwriters Laboratory lists CO/ALR devices primarily for use with aluminum wire because they use special metals at the terminal areas that are compatible with aluminum wire. Aluminum wiring has “Al” or “Aluminum” marked every few feet along the length of its insulating jacket. CO/ALR wiring devices, like the one shown above, have special terminals designed just for aluminum wiring. How can you tell if your home has aluminum wiring?

One way is to visually inspect the bare wiring at the circuit breakers in the panel box. Look for the silver color typical of aluminum wire. You can also identify aluminum wire by visually inspecting any exposed house wiring, such as the wires in an attic, garage, or unfinished basement. Aluminum wiring has “Al” or “Aluminum” marked every few feet along the length of its insulating jacket. Also watch for the warning signs that typically precede a serious electrical problem. These signs include faceplates on outlets or switches that are warm to the touch, lights that flicker on and off, circuits that no longer work, and the smell of burning plastic at outlets or switches. Because of the potential dangers posed by aluminum wiring, the Leviton Institute advises homeowners not to open, disassemble or touch any electrical panels, devices, or components if you are not familiar with aluminum wiring. Other areas in the house that should be inspected include lighting fixtures, such as chandeliers and outdoor porch lights, and appliances that are wired directly to a branch circuit, such as an air-conditioning unit. If you suspect that your home has aluminum wiring, have a qualified electrician conduct a thorough home inspection. Even room additions or circuits rewired or added between 1965 and 1973 may contain aluminum wiring.

It should be noted even though Ontario Hydro supports the use of aluminum wiring some insurance companies will not insure homes with aluminum wiring installed.

Supplied for your information by The Alliston Home Inspector

Originally posted 2010-01-19 06:56:43. Republished by Blog Post Promoter