Articles - Aluminum Wire Fire Hazards

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Aluminum Wire Fire Hazards:

The U.S. Consumer Products Safety Commission estimates that the likelihood of having a connection reach fire hazard condition in a house wired with "old technology" aluminum wiring (manufactured prior to 1972) is 40 to 50 times that of a house wired with copper wire. There is genuine increased fire risk with such a home and the homeowner should make modifications to the house wiring system to lessen the risk.

Number of Affected Houses: It is estimated that there are approximately 2+ million homes across the U.S. that are "aluminum wired." These are predominantly tract built homes constructed between the years 1965 and 1972.

Distinguishing the Wiring Type: The wiring that is of concern is the LOWER BRANCH wiring that distributes power to the plug-in receptacles, the switches and lights, the kitchen countertop plugs and the minor appliances such as disposer, dishwasher, furnace and washing machine. This is single strand wire and solid aluminum. (This wiring is distinguished from copper clad aluminum and all others.)

There are differing generations of aluminum single strand wire but the solid aluminum wires are all considered essentially the same, higher risk. Most modern houses employ some aluminum wiring. Entrance cables from the street and through the meter to the distribution panels are most often aluminum as are the heavier 240 volt circuits that feed the major appliances in homes. An "aluminum wired" house is distinguished by the existence of single strand solid aluminum general lighting and minor appliance wiring.

The Idiosyncracies of the Problem: The problem is not with the wire itself, it is intermittent hot connections where the wires join together or connect to devices. The reasons for this are not absolutely known but seem to center on the following factors:

1. Aluminum wire has a higher coefficient of expansion than copper and expands more when current passes through it. This can contribute to loosening at the connections.
2. Aluminum wire must be slightly thicker than copper to carry the same loads and this sizing difference may have contributed to loosening connections in early applications.
3. Metals in an oxygen atmosphere oxidize. Copper that oxidizes forms a conductor while aluminum oxide is a resistor. The resistance at the connections causes heat to build.
4. Unlike metals which connect can cause an oxide build as well and this may have caused an increased difficulty when aluminum wire was joined to devices intended for copper wire. The oxide added resistance.
5. The problem seems to increase as time goes by. This would seem to be due to increased loosening and oxide build.

Danger Signals: Here are some symptoms that you may have aluminum wiring in your house or that your aluminum wiring may have connection problems.

1. Flickering lights.
2. Unusual static on radio or TV.
3. Reduced TV picture size.
4. Arcing or sparks coming from switches or receptacles.
5. Cover plates on switches or plugs hot/warm to the touch.
6. Plugs and lights that don't work. Dead circuits.
7. Circuit breakers that trip for no apparent reason.
8. Arcing sounds within main distribution panels.
9. Melted insulation on conductors near connections.
10. Burning plastic odors near plugs or switches or lighting.
11. Smoke from switches or plugs or junction boxes.
12. Light bulbs that burn out quickly or shine unusually bright.

Making Aluminum Wiring Safer: A variety of modifications have been practiced over the years but only the "COPALUM" method is considered acceptable by the U.S. Consumer Products Safety Commission.

1. The various switches and plugs can be changed to those carrying the label, COALR, which is a more compatible metal to connect aluminum to. This is relatively inexpensive (about $6.00 to 8.00 per device) but it does not address the loosening potential or those connections made within junction boxes or within the main distribution panel itself.

2. Pigtailing with copper wire attached with SCOTCHLOK connectors and PENATROX A antioxidant compound. The aluminum wire is attached to a short section of copper wire with a compatible wire nut and reattached to the device. Both the aluminum and copper wires are first cleaned with an approved antioxidant compound. This method addresses all of the connections and is somewhat more expensive. ($7.50 to $9.00 per connection.)

3. Crimp connecting with the AMP COPALUM connectors. This method is similar to the above method except that a cylindrical device is placed over the wires and then is crushed to cold weld the wires together permanently. This method is the US CPSC accepted one and is considered the highest quality risk reduction method available. Because it involves more time and equipment, it is more expensive. The cost is approximately $12 to $15 per opening or connection.

Warning: Working with older aluminum wire is more difficult than working with copper wire. An inexperienced electrician can do more harm than good. Aluminum wiring safety retrofits are best left to specialists.
For further information on this subject we refer you to:

"How to make your aluminum wiring safer."
Technical Dynamics Publishing Department
402 Riverside Drive
Pasadena, MD 21122

"Repairing Aluminum Wiring"
U.S. Consumer Products Safety Commission
Washington, D.C. 20207
8006388326

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