Aluminum wiring was used extensively in the residential market from 1965 to 1976, but is no longer a popular wiring material for branch circuits. Problems have been reported from the overheating and failure of aluminum wiring terminations. Symptoms of this include receptacle discolouration, flickering lights, the smell of hot plastic insulation and sometimes an electrical-induced static noise on the radio and/or television.
Aluminum wiring in a home will operate as safely as any other type of wiring if the proper materials are used and it is installed to the manufacturer’s instructions and the Electric Safety Code of the jurisdiction where you live.
If you are trying to sell a home with aluminum wiring, one of the biggest obstacles will be when the potential buyers try to obtain insurance. The insurance underwriter often insists on having the electrical system inspected by a licensed electrician who has experience in inspecting and repairing aluminum wiring.
Your home inspector should strongly recommend that you hire a qualified electrical contractor experienced in repairing aluminum wiring to do a thorough inspection of the electrical system, even if the insurance company does not request one.
The inspection should include the following:
1. Visually check terminations at devices without removing or disturbing the devices.
2. Cut back any damaged aluminum conductors and join these to a copper tail using an approved connector for use with aluminum. These connectors are brown or purple depending on the manufacturer.
3. The copper tail is then terminated at the terminal screws of an approved ordinary device.
4. Sometimes the damaged section can be cut back, removing the damaged aluminum conductors and re-terminated at a new device bearing the marking CO/ALR.
5. Only devices bearing this CO/ALR marking are currently approved for use with aluminum wiring.
6. Panel board terminations should be checked for signs of overheating.
7. Fuses installed for heavy loads should be temperature sensitive Type D or Type P.
8. Circuits should never be overloaded or over fused regardless of wiring type.
Someone who has not examined the wiring in your house cannot reliably assure you about the condition that this wiring is in. Yet, in response to inquiry by owners or buyers of homes containing aluminum electrical branch wiring, there have been reports that some individuals in the field say the aluminum wiring in your house is not likely to be a problem.
The condition of aluminum electrical wiring connections vary greatly from house to house and even from branch circuit to branch circuit within a particular house. It is possible for very unsafe conditions to be present, but not visible, in any house with aluminum branch circuit wiring.
It is inaccurate and even dangerous for anyone to make any representation about the condition of aluminum wiring in a specific property without an on-site inspection.
Are the connections to the aluminum wire in any branch circuit safe? Without determining what types of connections are in the system and how they were made, nobody can answer the question definitively.
Are the receptacles “push-in” or “screw-terminal” type? If screw-terminal wired, how is the wire placed under the screw? (Does the wire go straight in or is it wrapped around the connector)? Are the screws steel or brass? Are the screws plated with zinc on the neutral side? What kind of splicing connectors exist in the system? If they are twist-on connectors (“wire nuts”), are they the live spring or restrained spring type? Did the installer clean the aluminum wire to remove the oxide before making the connection?
Were the spliced wires pre-twisted together? Was a proper corrosion inhibitor used on all connections?
Only after having the answers to all of these questions (from direct observations), can an evaluation of the relative safety of the wiring system be made.
These types of questions cannot be answered by a visual home inspection. Consequently, when a house contains any branch aluminum wire circuits, the client is strongly advised to have the electrical system thoroughly inspected by a qualified, licensed electrical contractor familiar with aluminum wiring.