The Dangers Of Aluminum House Wiring

During the second half of the sixties and seventies, aluminum wire became quite popular with residential electrician. It was cheaper than copper wire. It was also lighter than copper wire and easier to install. Aluminum wiring is rarely used in residential wiring anymore except for the service entrance wiring. In fact, most jurisdictions no longer allow its use for branch circuit wiring. It is far too dangerous for the inexperienced electrician to install.

Every year there are over 40,000 residential electrical fires in the United States. That is more than 100 residential electrical fires every day and over 50 percent of those fires are attributed to problems with the "Fixed Wiring." According to the Consumer Product Safety Commission (CPSC), there were 5,300 residential electrical fires in 2003 traced to problems with receptacle wiring. Those fires claimed the lives of 40 people and injured 110 more people. The National Fire Protection Association (NFPA) estimates that 5,000 fires start at switches, receptacles, and lighting outlets each year. A study conducted by the NFPA and CPSC show that aluminum-wiring connections were 55 times more likely to be involved in fires than copper connections.

Aluminum wire, when properly installed, is just as safe as copper wire, but aluminum wire is much less forgiving than copper wire and there in lies the problem for the inexperienced electrician.

The "Cold Creeps."

The biggest threat presented by aluminum wiring is a fundamental metallurgical aspect of metal and goes by the name  "Cold Creeps." Metals expand and contract as they are heated and cooled. Copper and aluminum both expand and contract as heated and cooled but aluminum expands and contracts at a higher rate than copper and there in lies the problem. Every time aluminum expands and contracts, connections made with it lose a little tightness. As the joints become looser, they begin to arc and the arcing generates heat that softens the wire’s insulation and sets it on fire.

The Problem Of Corrosion And Oxidation

Aluminum oxidizes or corrodes when it makes physical contact with certain other metals, metals like copper and brass. The oxidation that builds up on the wire and the terminals associated with it causes a high resistant connection to develop. The high resistance causes a voltage drop to develop across it, and this voltage drop causes the connection to heat up.

Combine the heat developed by the arcing caused by "Cold Creep" and the voltage drop across a high resistant connection caused by oxidation and you have a fire waiting to happen. The arcing of loose connections can produce enough heat to melt the device.

Not All Devices Are Created Equal

If you are like most do-it-yourself electricians, you have a variety of receptacle outlets and switches lying around your shop. They may be new or used. They may work OK with copper wire, but you may or may not be able to use these devices with aluminum wiring. You have to use devices rated for use with aluminum wiring. The receptacles, switches, light fixtures, and other devices used with aluminum wiring must be stamped with "Al/Cu" or "CO/ALR." These devices are more expensive than non-rated devices, but they are the only one that you can safely use with aluminum wiring.

Do Not Take The Easy Way Out

Modern devices come with two means of connecting the circuit wires to them, screw terminals and "Push-In" terminals. It takes a couple of minutes longer to make connections using the screw terminals. You have to strip the wire, make a loop in the end with needle nose pliers, place the loop under the screw in a clockwise direction, and then tighten the screw. The "Push-In" terminals are quicker because all you have to is strip ¾ inches of insulation from the wire and then push the stripped end in the hole. They are time savers but never use them with aluminum wire. "Cold Creep" makes them insecure and unsafe.

Connecting Aluminum Wire To Copper Wire

Connecting copper wire to an existing aluminum wire requires the use of specific crimp sleeve connectors and a special powered crimping tool. You use Tyco Products, COPALUM crimp sleeves filled with antioxidant grease. The power crimper exerts enough pressure to produce a "Cold Weld," creating a permanent bond between the two conductors. The "Cold Weld" created by the Tyco Products COPALUM crimping tool is resistant to "Cold Creep" and oxidation. You have to be a licensed, certified electrician to buy the AMP/TYCO tool. If you cannot borrow one from a licensed electrician who trusts your electrician skills, call an electrician.

The Case Of The Purple Wire Nut

There is another device available for splicing aluminum wire and copper wire together, the "Purple Wire Nut." These wire nuts are UL Approved for such use but I have not encountered any. Their antioxidant compound may prevent oxidation from occurring where the copper and aluminum wires make contact but there is still the problem of "Cold Creep" which would concern me. The "Purple Wire Nut" was designed to make pigtail splices using a short length of copper wire so non-rated devices could be used with aluminum wiring system. They are UL Approved so they are safe for the purpose they were designed but I do not know any professional electricians who use them.

I do not mean to repeat myself but this is worth repeating. Aluminum wiring is not forgiving; it leaves no room for mistakes. If you are not comfortable with your skills as a do-it-yourself electrician, call in the professionals who receive individual training in working with aluminum wiring.