Aluminum wiring can be a problem in homes. The circuits involved will most likely be those supplying the lights, outlets, clothes dryer and water heater.
How to find out if you have it…
This can usually be done by looking at the electrical wiring, either between the open floor joists, in the basement, up in the attic, or at the service panel. If the wiring is aluminum and was manufactured before May 1977, the outer covering of the cable will be marked, at least every 12 inches, with the word ALUMINUM, or an abbreviation, ALUM, or AL. If the cable was manufactured after May 1977, the marking may be either ALUMINUM ACM, ALUM ACM, or AL ACM.
Sometimes a mixture of aluminum and copper wiring is installed. If you find that the wiring installed for lights and wall plugs is aluminum, then it’s important that the CO/ALR devices, described below, be used for replacement of wall switches and receptacles.
Aluminum wiring is safe if properly installed.
Use only CO/ALR wall switches and outlets. If your home has aluminum wiring and you need to replace a switch or outlet, the replacement should be a type that is specifically approved for use with aluminum wiring. Approved devices are marking “CO/ALR”. This means “Copper Aluminum Revised” to differentiate these devices from earlier models. The CO/ALR marking identifies the equipment as having been tested and found suitable for use with aluminum or copper wiring.
Why is it so important to install only CO/ALR devices?
When the insulation is stripped from aluminum wire and the wire is exposed to air, an insulating film immediately forms on the wire, causing a poor connection resulting in overheating at the switch or outlet unless the terminal or the device is built with the right contacts designed to break through the film and ensure a good connection.
Devices marked CO/ALR are specifically designed and approved to ensure a good connection through the use of a larger contact area and compatible materials. When connecting to switches and outlets, the wire should be formed in a clockwise direction around the screw into three fourths of a complete loop.
When buying wire connectors for connecting aluminum wires, purchase those specifically marked for use with aluminum wiring. When connecting solid aluminum wire to stranded wire, “Special Service” connectors are recommended. These should also be used with baseboard heaters, water heaters and other large load pieces of equipment.
NOTE: Because of the specialized knowledge and techniques required for working with aluminum wiring, it is recommended that it should be upgraded by qualified electrician.
If you notice any of the following conditions in your home, the causes should be investigated:
- Warm face plates on switches (other than dimmer switches) or receptacles
- Strange or distinctive odors coming from outlets or switches
- Persistent but intermittent flickering of lights that can’t be traced or external causes
- Unusual static on radio or television.
For more information visit the CSPC site.