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Penney Electric Inc |
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Aluminum Wiring In Homes
Between approximately 1965 and 1973, single-strand aluminum wiring was sometimes substituted for copper branch-circuit wiring in residential electrical systems 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 led 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 homeowner’s insurance policy. Homeowners should talk with their insurance agents about whether the presence of aluminum wiring in their home is a problem that requires changes to their policy.
Failing aluminum-wired connections seldom provide easily detected warning signs. Aluminum-wired connections and splices have been reported to fail and overheat without any prior indications or problems as stated per The U.S. Consumer Product Safety Commission (CPSC).
Facts and Figures
In April 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, when fire hazards become likely.
These qualities are:
Identifying Aluminum Wiring
Fixing The Problem
Aluminum wiring can be replaced or repaired to effectively and permanently reduce the possibility of fire and injury due to failing (overheating) wire connections and splices. Only a qualified electrician should perform this remediation. Other than complete replacement of aluminum wire with copper wire, there may be other potential solutions for the permanent repair of hazardous aluminum wire connections and splices.
CPSC recommend repair methods only where there is satisfactory, documented evidence that the methods meet the following criteria:
• Permanent. The method must affect a permanent repair. Such as Rewiring the home with a complete replacement of copper cable. The pro and con for this solution is that while it is permanent it may be cost prohibitive. Methods designed to address temporary or emergency repair situations, but which may fail over time, are not considered permanent.
• Safe & Effective. The method must be effective and successfully eliminate or substantially mitigate the fire hazard. The more affordable solution to a complete rewire Pigtailing.
What is Pigtailing?
As an alternate to rewiring the home with copper, the next best method is attaching a short section of copper wire to the ends of the aluminum wire at each connection points (a technique commonly referred to as “pigtailing”), using a special connector to join the wires. The CPSC considers pigtailing to be a safe and permanent repair of the existing aluminum wiring. The repair should include every connection or splice involving aluminum wire in the home, including outlets, dimmers, switches, fixtures, appliances, and junction boxes. The repaired system, with short copper wire extensions at every termination throughout the home, permits the use of standard wiring devices, including receptacles and switches.
Between approximately 1965 and 1973, single-strand aluminum wiring was sometimes substituted for copper branch-circuit wiring in residential electrical systems 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 led 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 homeowner’s insurance policy. Homeowners should talk with their insurance agents about whether the presence of aluminum wiring in their home is a problem that requires changes to their policy.
Failing aluminum-wired connections seldom provide easily detected warning signs. Aluminum-wired connections and splices have been reported to fail and overheat without any prior indications or problems as stated per The U.S. Consumer Product Safety Commission (CPSC).
Facts and Figures
In April 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, when fire hazards become likely.
These qualities are:
- 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 that 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.
Identifying Aluminum Wiring
- Aluminum wires are the color of aluminum and are easily discernible from copper and other metals.
- Since the early 1970s, wiring-device binding terminals for use with aluminum wire have been marked CO/ALR, which stands for “copper/aluminum revised."
- Look for the word "aluminum" or the initials "AL" on the plastic wire jacket. Where wiring is visible, such as in the attic or electrical panel, homeowners can look for printed or embossed letters on the plastic wire jacket. Aluminum wire may have the word "aluminum," or a specific brand name, such as "Kaiser Aluminum," marked on the wire jacket. Where labels are hard to read, a light can be shined along the length of the wire.
- When was the house built? Homes built or expanded between 1965 and 1973 are more likely to have aluminum wiring than houses built before or after those years.
Fixing The Problem
Aluminum wiring can be replaced or repaired to effectively and permanently reduce the possibility of fire and injury due to failing (overheating) wire connections and splices. Only a qualified electrician should perform this remediation. Other than complete replacement of aluminum wire with copper wire, there may be other potential solutions for the permanent repair of hazardous aluminum wire connections and splices.
CPSC recommend repair methods only where there is satisfactory, documented evidence that the methods meet the following criteria:
• Permanent. The method must affect a permanent repair. Such as Rewiring the home with a complete replacement of copper cable. The pro and con for this solution is that while it is permanent it may be cost prohibitive. Methods designed to address temporary or emergency repair situations, but which may fail over time, are not considered permanent.
• Safe & Effective. The method must be effective and successfully eliminate or substantially mitigate the fire hazard. The more affordable solution to a complete rewire Pigtailing.
What is Pigtailing?
As an alternate to rewiring the home with copper, the next best method is attaching a short section of copper wire to the ends of the aluminum wire at each connection points (a technique commonly referred to as “pigtailing”), using a special connector to join the wires. The CPSC considers pigtailing to be a safe and permanent repair of the existing aluminum wiring. The repair should include every connection or splice involving aluminum wire in the home, including outlets, dimmers, switches, fixtures, appliances, and junction boxes. The repaired system, with short copper wire extensions at every termination throughout the home, permits the use of standard wiring devices, including receptacles and switches.
