Between approximately 1965 to the late 70's, single-strand aluminum wiring was sometimes substituted for copper branch-circuit wiring in residential electrical systems Aluminum and copper wiring, with each metal clearly identifiable by its color due to the sudden escalating price of copper. After a decade of use by homeowners and electricians, inherent weaknesses were discovered in the metal that lead to its disuse as a branch wiring material. Although properly maintained aluminum wiring is acceptable, aluminum will generally become defective faster than copper due to certain qualities inherent in the metal. Neglected connections in outlets, switches and light fixtures containing aluminum wiring become increasingly dangerous over time. Poor connections cause wiring to overheat, creating a potential fire hazard. In addition, the presence of single-strand aluminum wiring may void a home’s insurance policies. Inspectors may instruct their clients to talk with their insurance agents about whether the presence of aluminum wiring in their home is a problem that requires changes to their policy language.
FACTS AND FIGURES
On April, 28, 1974, two people were killed in a house fire in Hampton Bays, New York. Fire officials determined that the fire was caused by a faulty aluminum wire connection at an outlet.
According to the Consumer Product Safety Commission (CPSC), "Homes wired with aluminum wire manufactured before 1972 ['old technology' aluminum wire] are 55 times more likely to have one or more connections reach "Fire Hazard Conditions" than is a home wired with copper."
ALUMINUM AS A METAL
Aluminum possesses certain qualities that, compared with copper, make it an undesirable material as an electrical conductor. These qualities all lead to loose connections, where fire hazards become likely. These qualities are as follows:
- higher electrical resistance. Aluminum has a high resistance to electrical current flow, which means that, given the same amperage, aluminum conductors must be of a larger diameter than would be required by copper conductors.
- less ductile. Aluminum will fatigue and break down more readily when subjected to bending and other forms of abuse than copper, which is more ductile. Fatigue will cause the wire to break down internally and will increasingly resist electrical current, leading to a buildup of excessive heat.
- galvanic corrosion. In the presence of moisture, aluminum will undergo galvanic corrosion when it comes into contact with certain dissimilar metals.
- oxidation. Exposure to oxygen in the air causes deterioration to the outer surface of the wire. This process is called oxidation. Aluminum wire is more easily oxidized than copper wire, and the compound formed by this process – aluminum oxide – is less conductive than copper oxide. As time passes, oxidation can deteriorate connections and present a fire hazard.
- greater malleability. Aluminum is soft and malleable, meaning it is highly sensitive to compression. After a screw has been over-tightened on aluminum wiring, for instance, the wire will continue to deform or “flow” even after the tightening has ceased. This deformation will create a loose connection and increase electrical resistance in that location.
- greater thermal expansion and contraction. Even more than copper, aluminum expands and contracts with changes in temperature. Over time, this process will cause connections between the wire and the device to degrade. For this reason, aluminum wires should never be inserted into the “stab,” “bayonet” or “push-in” type terminations found on the back of many light switches and outlets.
- excessive vibration. Electrical current vibrates as it passes through wiring. This vibration is more extreme in aluminum than it is in copper, and, as time passes, it can cause connections to loosen.
IS ALUMINUM WIRING SAFE?
Aluminum wiring is an acceptable wiring choice if properly installed and used in the proper application. Problems began to show up where aluminum was used in branch circuit wiring. These are the smaller wires that deliver electricity from the electrical panel to the plugs, switches and lighting fixtures. Aluminum tends to oxidize when exposed to air, resulting in overheating, and eventual failure at the termination points. Since aluminum wire is softer and exhibits different electrical characteristics than copper wiring, particular attention is necessary to verity that appropriate devices are being used. As with all wiring, aluminum is safe provided appropriate connections and terminations are made without damaging the wire and with approved materials installed in conformity with the Canadian Electrical Code. Today, stranded aluminum cable is mostly used for main distribution wiring or feeder lines to bring electricity to the home.
When houses are wired with aluminum wiring most insurance companies require a complete electrical safely inspection by a professional and licensed electrical contractor before policies are sold or renewed. Electrical modifications are generally needed and in some cases complete rewiring is advised to reduce the risk of a house fire.
HOW DO I KNOW IF MY HOME HAS ALUMINUM WIRING?
Houses constructed between the mid 1960’s until the late 1970’s could have aluminum wiring. You might be able to check the wiring yourself. This may be done by looking at the electrical wiring visible, either between the open floor joists, in the basement, up in the attic, or at the service panel, check if the wire is marked with the work ALUMINUM or ALUM, AL, ALUM ACM, AL ACM.
SOME SYMPTOMS THAT MAY INDICATE PROBLEMS WITH ALUMINUM WIRINGARE:
- Flickering lights that can’t be traced to a failing bulb or other external cause.
- Plugs that don’t work even with the circuit energized.
- Uncommon static on the radio, TV or computer.
- Switch plates and receptacle covers that are crooked, discolored or warm.
- Circuit breakers or fuses that trip for no evident reason.
- Unusual odor similar to that of burning plastic around switches and receptacles.
- Smoke or sparking close to electrical devices.
If you observe any of these problems, it is important to have a licensed Vancouver electrical contractor check the electrical system immediately to determine the best and securest solution to this safety concern.
IS THERE A SOLUTION TO MY ALUMINUM WIRING PROBLEMS?
Yes, BC homeowners have three ESA authorized options, when addressing the concerns of aluminum wiring.
1. Installation of CO/ALR or AL/CU devices only.
It involves replacing all the wall receptacles and switches in the house with ones that are specifically rated for aluminum wiring. “Decora” devices and Tamper Resistant receptacles are not available in a CO / ARC form. Availability islimited to standard devices. This option does not address connections in lighting fixtures.
2. Copper Pigtails with Specialized Connectors.
The most usual method of addressing this problem is bridging a new copper pigtail wire between the existing aluminum wiring and any electrical device. This connection must be done using very specialwire connectors along with appropriate anti-oxidant paste to increase conductivity and eliminate corrosion.
3. Complete home rewire using only copper wiring.
Clearly this is the securest long term solution to the aluminum wire dilemma. It is the most labor intensive and expensive method, with investments ranging from $7,000 to $20,000 plus, depending on the size of the home. This option would help to protect the value of the home.
All three of these options should be performed by a professional and licensed Vancouver electrical contractor to ensure right installation procedures are strictly followed.
In summary, aluminum wiring can be a fire hazard due to inherent qualities of the metal. Inspectors should be capable of identifying this type of wiring.