residential, commercial, electrician, cincinnati


During the mid-1960’s and early 1970’s aluminum (instead of copper) wiring became quite popular and was widely used in the home building process by electrical contractors. Since that time, aluminum wiring has been implicated in a number of house fires, and most jurisdictions do not allow its use with the exception of some 240 volt circuits based upon the termination equipment or device. We recommend that you do not have it installed in your home unless it is service entrance cable for the main service or a sub panel.  Aluminum wiring, when properly installed, can be just as safe as copper. Aluminum wiring is, however, very unforgiving of improper installation.

The main problem with aluminum wiring is a phenomenon known as “cold creep”. When aluminum wiring warms up, (load is applied) it expands. When it cools down, (load is turned off) it contracts. Unlike copper, when aluminum goes through a number of warm/cool cycles it loses a bit of tightness each time. To make the problem worse, aluminum oxidizes, or corrodes when in contact with certain types of metal, so the resistance of the connection increases, which causes it to heat up and corrode/oxidize still more. Eventually the wire may start getting very hot, melt the insulation or fixture it’s attached to, and possibly even cause a fire.

According to the U.S. Consumer Product Safety Commission, there have been many hazardous safety issues reported with aluminum wiring such as fire and even deaths to have been caused by aluminum wiring problems. Problems due to this expansion, or more likely micro-fretting and arcing at the connections can cause overheating at connections between the wire and devices or at splices. These connections can become hot enough to start a fire without ever tripping the circuit breaker.

CPSC research shows that “homes wired with aluminum wire manufactured before 1972 are 55 times more likely to have one or more connections reach “Fire Hazard Conditions” than are homes wired with copper. “Post 1972 “aluminum wire is also a concern. Introduction of the aluminum wire “alloys” in 1972 time frame did not solve most of the connection failure problems. It should be noted that aluminum wiring is still today permitted and used for certain applications, including residential service entrance wiring and single purpose higher amperage 240 volt circuits such as air conditioners, dryers, or ranges. The fire risk from single purpose circuits is much less than for branch circuits to receptacles, switches or light fixtures. But it’s not necessarily because of “new alloy” as some people assert. It’s because there are enormously fewer connections and thus statistically a smaller chance of a connection failure. These connections do still burn up, as indicated by field report studies.


Since most people usually discover aluminum wiring during a home inspectors report or after they have moved into a home, we want to cover a few basic points of safe aluminum wiring. We suggest that, if you are considering purchasing a home with aluminum wiring, or have discovered it later, that you hire a LICENSED electrician to check over the wiring for the following reasons.

  • ·        Look for signs of overheating or discoloration on devices (receptacles or switches) or cover plates. Visibly inspect for any signs of dark connections, melted insulation or wirenuts connectors. Any such damage should be repaired immediately.


  • ·        Devices (receptacles or switches) directly connected to aluminum wiring should be rated and identified with a stamped marking of “Al/Cu” or “CO/ALR”. If you do not see this stamped marking on the yoke of the device it should be replaced or a proper connector should be used in the transition from aluminum to copper wiring. Note: The “CO/ALR” devices are still available but are somewhat more expensive.


  • ·        The wire at these devices regardless whether it is aluminum or copper should be properly connected (at least ¾ of the way around the screw in a clockwise direction).  These connections should be tight and any time that you remove a device from its mounting box the wiring terminations should be checked for tightness.


  • ·        Manufacturers for years have provided devices (receptacles and switches) with “push-in” connection terminals. We do not recommend this termination method and are especially hazardous with aluminum wire. Any connections using push-in terminals should be removed and a proper device with screw terminals should be installed immediately.


  • ·        Connections between aluminum and copper wire need to be handled properly with approved methods. The National Electric Code requires that the wire be connected together using special crimp devices or mechanical connectors, with an anti-oxidant grease. This should be left for a professional licensed electrician. We use alumiconn connectors. These connections are quite commonly known as “pigtailing” a copper wire onto the homes aluminum wiring inside the electrical box behind the device.

 ·        Best practice is to remove the aluminum wiring and replace it with newer copper wire, but this can be expensive.