Dear Mr. Electrician: I am planning to have the electrical service to my house upgraded. The licensed electrical contractor that I am using will be installing aluminum wire for this installation. Is aluminum wire safe to use?
Answer: Yes it is safe to use aluminum wire for new installations and for upgrades. Aluminum wire does have a questionable past, and problems still occasionally surface to this day from improper installations that date back to the 1960’s and 1970’s. However new types of wires, aluminum rated wiring devices, and equipment with an aluminum wire approval have all been tested to be safe. Click here to read a short history of “Aluminum Building Wire” published on WikipediA.
Aluminum Wire Inspection
If you own a house that was built in the 1960’s or 1970’s and it was wired with aluminum wiring throughout, there is no need to panic. However you will need to take some steps to be sure that the wiring is currently in good operating condition and is properly installed. It is possible that a previous owner took the necessary precautionary measures, but you have no idea if they were done correctly unless you investigate.
The simplest thing to do is to have a look at your electrical switches and receptacles from inside. This entails removing them from the wall with the power turned off at the circuit breaker box. This must be done very carefully where aluminum wire is installed. The old aluminum wire does not have the flexibility of copper. Consequently it can break very easily upon the removal of a wiring device from the wall and make matters worse. If you are not comfortable with doing this, please call a licensed electrical contractor to have a look. Aluminum wire must be connected to a wiring device that is approved for aluminum wire. It will have a Co/ALR designation somewhere on the switch or receptacle.
Repairing Aluminum Wire Connections
The best procedure to make your existing aluminum wiring safe at every electrical receptacle and wall switch is to pigtail the aluminum conductors with copper wire. I usually use stranded copper wire for the additional flexibility. Small aluminum conductors tend to break easily after only a couple of bends. Repairing bad aluminium wire connections can be accomplished using one or more methods.
The best and most recommended technique for aluminum wire repair is called the Copalum method. Basically it is a specifically designed crimper for aluminum conductors. It uses a crimp sleeve designed and approved for use with this tool and for the aluminum wire to copper connection. Unfortunately the Copalum method is proprietary and the user must be trained and licensed by the manufacturer to use the tool and purchase the necessary supplies. Consequently you must call a licensed electrical contractor who has been factory approved to do the necessary corrections to make your wiring safe using the Copalum method. Not all electrical contractors have taken the time to get approved to use the Copalum method so it may take several phone calls to find someone to do the work.
Another aluminum wire repair technique is to use twist-on aluminum wire connectors that are specifically designed for aluminum and copper connections. I think connecting stranded copper wire to the aluminum wire is the best because it allows more flexibility for installing a wiring device and puts less strain on the aluminum conductors in the process. The aluminum wire connectors are more expensive than standard twist-on wire connectors, but they are tested and approved for the aluminum and copper wire connections.
Another approved aluminum to copper connection choice is to use push-in aluminum wire connectors that are rated for aluminum wire. These also cost more than regular push-in wire connectors.
Usually when an electrician works with larger sizes of aluminum wire he or she will coat the bare terminating wire end with a coating of anti-oxidant compound to stop one of the main problems with old aluminum wire, oxidation.
Some of my posts on old house wiring might be of interest.