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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 systemsAluminum and copper wiring. Each metal is clearly identifyable 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.
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, inspectors 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.
Options for Correction
Aluminum wiring should be evaluated by a qualified electrician who is experienced in evaluating and correcting aluminum
wiring problems. Not all licensed electricians are properly trained to deal with defective aluminum wiring. The CPSC
recommends the following three methods for correction for aluminum wiring:
- Rewire the home with copper wire. While this is the most effective method, rewiring is expensive and impractical, in most
- Use copalum crimps. The crimp connector repair consists of attaching a piece of copper wire to the existing aluminum
wire branch circuit with a specially designed metal sleeve and powered crimping tool. This special connector can be
properly installed only with the matching AMP tool. An insulating sleeve is placed around the crimp connector to complete
the repair. Although effective, they are expensive (typically around $50 per outlet, switch or light fixture).
- Use the approved Alumiconn connectors for connecting wiring.
Although not recommended by the CPSC as methods of permanent repair for defective aluminum wiring, the following
methods may be considered:
- Application of anti-oxidant paste. This method can be used for wires that are multi-stranded or wires that are too large to
be effectively crimped.
- Pigtailing. This method involves attaching a short piece of copper wire to the aluminum wire with a twist-on connector. the
copper wire is connected to the switch, wall outlet or other termination device. This method is only effective if the
connections between the aluminum wires and the copper pigtails are extremely reliable. Pigtailing with some types of
connectors, even though Underwriters Laboratories might presently list them for the application, can lead to increasing
the hazard. Also, beware that pigtailing will increase the number of connections, all of which must be maintained.
Aluminum Wiring Repair (AWR), Inc., of Aurora, Colorado, advises that pigtailing can be useful as a temporary repair or
in isolated applications, such as the installation of a ceiling fan.
- CO/ALR connections. According to the CPSC, these devices cannot be used for all parts of the wiring system, such as
ceiling-mounted light fixtures or permanently wired appliances and, as such, CO/ALR connections cannot constitute a
complete repair. Also, according to AWR, these connections often loosen over time.
- Replace certain failure-prone types of devices and connections with others that are more compatible with aluminum wire.
- Remove the ignitable materials from the vicinity of the connections.
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.
Below are safety recalls from the Consumer Product Safety Commission concerning aluminum wiring in homes.
CPSC Safety Recommendations For Aluminum Wiring In Homes
WASHINGTON, D.C. (June 1974) -- The U.S. Consumer Product Safety Commission held four days of fact-finding hearings on
March 27 and 28 in Washington, D.C., and on April 17 and 18 in Los Angeles, California, to seek information about possible
hazards associated with the use of aluminum in home electrical wiring systems.
The Commission has received numerous reports about home fires that have been attributed to the use of aluminum conductors
in branch circuits. Many of these fires have been the result of overheated terminals involving aluminum wiring and a receptacle
The Commission currently is evaluating the data presented at the hearings by consumers and representatives of industry and
government and conducting additional tests at the National Bureau of Standards to better understand the failure mechanism.
Further action by the Commission is dependent upon a finding that aluminum wiring is either a substantial product hazard or
poses an unreasonable risk of injury to consumers.
An estimated two million homes and mobile homes have been constructed using aluminum wiring since 1965.
To assist consumers who live in homes with aluminum wiring to reduce the potential risk of fire and the possibility of dangerous
overheating, the Commission suggests the following precautionary steps.
CONSUMERS WHO HAVE NOT HAD THOROUGH ELECTRICAL TRAINING SHOULD NOT ATTEMPT TO INSPECT
THEIR HOME WIRING SYSTEM OR MAKE ANY ELECTRICAL REPAIRS OR ADJUSTMENTS BEFORE SEEKING
EXPERT ADVICE. SERIOUS OR FATAL ELECTRIC SHOCK COULD RESULT.
1.If you are not certain or if you do not know whether your home is wired completely with aluminum, ask a knowledgeable
electrician or other qualified individual to make the determination. If aluminum wiring was used, have the electrician or
individual check the connections on heavily loaded and constantly loaded circuits to determine if the electrical connections
have been made properly or show evidence of deterioration.
2.Trouble signals associated with aluminum wiring problems include:
* warm switch or receptacle face plates.
* strange or distinctive odor or the smell of burning plastic in the vicinity of a receptacle or switch.
* flickering of lights not traceable to appliances or obvious external causes.
IF THESE TROUBLE SIGNALS ARE PRESENT IN YOUR HOME, SEEK EXPERT ADVICE IMMEDIATELY.
3.If it is necessary to replace wall switches and receptacle outlets, only devices which are designed specifically for use with
aluminum wiring should be used. These devices are labeled CO/ALR on the mounting strap.
Proper installation of the CO/ALR device is critical. The work should be performed only by a qualified electrician or individual
familiar with the techniques of using aluminum wiring. Proper techniques include the ability to remove the wire insulation without
nicking the wire, to wrap the wire with proper distance and direction around the terminal screw, to tighten the screw with the
proper torque, and to position the wires within the outlet box to avoid loosening the terminal connection. Complete installation
procedures are available at no cost by writing to Aluminum Wire Installations, U.S. Consumer Product Safety Commission,
Washington, D.C. 20207.
4.Pigtailing. A technique called pigtailing is sometimes used to improve aluminum wiring connections. Pigtailing involves
connecting a short piece of insulated copper wire between the aluminum wire and the switch or receptacle connecting
terminals. Although this technique may be an acceptable practice for new installations, the addition of more wires and splices
into existing outlet boxes is not generally recommended.
November 4, 1975
CPSC Invites Offerors For Aluminum Wire System Safety Standard
WASHINGTON, D.C. (Nov. 4) -- The U.S. Consumer Product Safety Commission today invited any interested person or group
to offer to develop a recommended consumer product safety standard for aluminum wire systems -- the wiring and devices --
currently used in residences, schools, recreational facilities, and other public buildings. The recommended standard so
obtained could later be adopted by the Commission as a mandatory Federal standard.
In a Federal Register notice published today, the Commission also invited any person or group to submit an existing standard
for aluminum wire systems for Commission consideration for adoption as a mandatory Federal standard.
According to the Commission, the major hazard associated with aluminum wire systems that needs to be addressed in a
safety standard is death or injury caused by burning or asphyxiation due to fire caused by defective connections within
aluminum wire systems.
The Federal Register notice defines the aluminum wire system as consisting of aluminum electrical conductors intended or
suitable for use in 15 and 20 ampere electrical circuits (generally 10 AWG (American Wire Gage) sizes and smaller) as well
as all devices connected to it, including outlets, wall switches, circuit breakers, fuse holders, lamp holders, wire connectors,
and relay switches.
Included in the definition is aluminum wire which is clad with any conductive coating, but not included is copper clad aluminum
conductors when the copper coating is 10 percent or greater of the conducting cross sectional area.
Since 1965, an estimated two million single family, multifamily, and mobile homes across the country have been wired with
The Commission has preliminarily determined that hazards associated with aluminum wire systems present an unreasonable
risk of injury or death on the basis of testimony received at two public hearings held in Washington, D.C., and in Los Angeles in
March and April 1974, research at the National Bureau of Standards, and hundreds of hotline calls and letters received from
consumers detailing problems with aluminum wire systems. The Commission has collected reports of over 165 aluminum
wiring failures and numerous aluminum wiring related-fires.
Between August 29 and September 17, 1974, the Commission's hotline received 404 phone calls from the New York area in
response to a newspaper article discussing the hazards of aluminum wire. Of those calls, 179 homeowners reported
hazardous conditions such as burned wire insulation, burned receptacles, fire in wall switches, the odor of burning wires,
overheated switches, scorched walls, and melted wire insulation.
The Commission received a petition from Southwire Company, Carrollton, Georgia, on August 27, 1974, asking the
Commission to adopt a standard submitted by it for aluminum conductors and associated devices. The Commission viewed
Southwire's petition in part as a request to commence a standard development proceeding, and, to this extent, responded to
the petition by a Commission decision to initiate such a proceeding. Southwire may re-submit its standard for CPSC
consideration as part of the standard development proceeding.
The Consumer Product Safety Act offeror procedures encourage and provide wide opportunities for participation by all
interested persons -- industry, trade associations, technical experts, and consumers -- in the standards development process
regardless of who is selected as offeror, a CPSC spokesperson said.
The Federal Register notice indicates that the Commission may agree to contribute to the cost of developing a proposed
regulation but anticipates that the bulk of the offeror's work will be done by voluntary effort or funded by non-Commission
Copies of the November 4th Federal Register invitation and injury and hazard data are available from the Office of the
Secretary. Existing standards and offers must be submitted by December 4, 1975 to the Office of the Secretary, U.S.
Consumer Product Safety Commission, 1750 K Street, N.W., Washington, D.C., 20207.
The development period will end 150 days after the notice is published in the Federal Register although the Agency may
extend the time period for good cause. Persons interested in participating in the development activities should also contact the
Office of the Secretary.
May 1, 2003
May Is National Electrical Safety Month: Good News for Homeowners - Aluminum Wiring Fix Still Available
WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission (CPSC) announced today that Tyco Electronics
Corp., of Harrisburg, Pa., has agreed to continue offering the COPALUM connector repair system until at least 2005 for homes
with aluminum wiring. The COPALUM repair system has benefited tens of thousands of consumers by reducing the risks of
dangerous overheating and fire that can be caused by failing aluminum wiring connections. It is estimated that 2 million homes
were built with aluminum wire between 1965 and 1973.
Warning signs, such as warm-to-the-touch face plates on outlets or switches, flickering lights, circuits that don't work, or the
smell of burning plastics, can indicate a fire hazard within 15- and 20-ampere aluminum wiring circuits. A failure in the circuits
can lead to electrical arcing and a serious fire, which can spread within the walls of a home before being detected.
The COPALUM crimp connector, which has been available for more than 20 years, is the only system recognized by CPSC
that provides a complete and permanent repair and reduces the fire hazard in aluminum wire circuits. The COPALUM
connector system attaches a copper wire to the old aluminum wires and is then crimped together with a power tool, achieving
a "cold weld" between the conductors. The "cold weld" creates a permanent bond that eliminates electrical arcing or glowing
connections and creates a safer electrical connection at outlets, switches, lights, circuit breakers, and panelboard terminals.
The COPALUM connector repair materials and power crimping tools are only available to electricians who receive training
from the manufacturer, to ensure that repairs are properly made.
"CPSC appreciates Tyco's commitment to protecting the safety of consumers by continuing to offer COPALUM connectors,"
said CPSC Chairman Hal Stratton. "Without the Tyco Electronics system, the only method for safely upgrading aluminum
wiring systems would be to install new copper circuits, which is often impractical for consumers."
CPSC believes that "twist-on" connectors, receptacles and switches and other devices that connect directly to aluminum wires,
are an inadequate solution. The COPALUM crimp connector system provides a safe, permanent fix.
If homeowners are not certain whether their home has aluminum branch circuit wiring, they can look at the markings on the
surface of the electric cables which may be visible in unfinished basements, attics or garages. Aluminum wiring will have "Al"
or "Aluminum" marked every few feet along the cable. A home inspector or qualified electrician also can assist in identifying
aluminum wiring. CPSC advises that consumers should not open the interior of the panelboard or circuit breaker compartment
- this can expose live wires and pose an electrocution hazard.
COPALUM connectors are available from Tyco Electronics under the AMP brand. Consumers can check to see if the
COPALUM connector system is available in their area by calling the company at (800) 522-6752. To order a list of authorized
electricians in their area, consumers can write to: Tyco Electronics Corp., Attn: Aluminum Wire Repair Program, P.O. Box
3608, Harrisburg, PA 17105-3608. If no authorized electrician is currently located nearby, consumers can have an electrician
interested in repairing their home contact the nearest supplier of AMP- brand COPALUM connectors for training and other
For more information about aluminum wiring and the crimp connector system, see "Repairing Aluminum Wiring" (pdf).
Consumers can also obtain a free copy of this booklet by writing to CPSC, Washington, DC 20207.
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