Dear Mr. Electrician: Is aluminum wiring safe to use? 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.
Answer: Yes it is safe to use aluminum wiring for new installations and for upgrades. NOTE: Some text links below go to applicable products on Amazon. As an Amazon Associate I earn from qualifying purchases.
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.
New types of wires, aluminum wire rated 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 WIRING 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.
The issues with the wiring at that time became apparent over time. It turns out that the alloys used to make that wire back then was subject to oxidation. As the oxidation at the connection points got worse, so did the resistance of the connection. This caused the connections to arc and burn and with a low melting point the wired connection would melt.
When that became apparent it was then required to use anti-oxidant compound on all aluminum wiring connections. However now the aluminum alloy has been changed and on new aluminum wiring installations it is not required to use an anti-oxidant unless specified by the manufacturer.
Another problem with the aluminum wire was that it had a greater expansion and contraction capacity over copper. So when the wire was under a large load such as an electric heater it would expand. Then when the load was off the wire would contract. Over time this caused the connections under screw terminals to become loose which led to arcing and burning and melting.
It is very important when installing aluminum wire that all connection and termination points are rated and approved for its use.
It is possible that a previous owner took the necessary precautionary measures to ensure that the existing aluminum wire is connected properly. However you will have no idea if the repairs were done or done correctly unless you investigate or have an inspector or electrician take a look.
The simplest thing to do is to have a look at your electrical switches and receptacles inside the electrical box. Turn off the power at the circuit breaker before doing this. If you remove the wall plate over a switch or electrical receptacle outlet you may be able to see the aluminum wires on the screw terminals. Shining a flashlight inside may help.
Try to see if there is an aluminum wire connected directly onto the screw terminal. Also look inside the electrical box for purple colored wire connectors which are commonly used for aluminum to copper wire connections.
If you see copper wire on the screw terminals and purple connectors inside of the electrical box, then it is very likely that particular outlet or switch was pigtailed correctly with copper wire and is safe from future aluminum wire issues.
If you cannot see clearly into the electrical box then the switch or outlet will need to be removed. 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.
Aluminum 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 conductors must be connected to a device that is approved for its use. It will have a Co/ALR designation somewhere on the switch or receptacle.
It is better to have copper pigtails connected to the switch or outlet rather than direct connections of the aluminum wire onto the devices. Copper wire is more flexible and can be bent many times before weakening and break. Aluminum wire will break after bending a couple of times. This is why it is more desirable to add copper pigtails.
I can speak from my own experience after connecting aluminum onto an approved outlet, I pushed it back into the electrical box and the wire broke. Now I used stranded copper wire for pigtailing to aluminum wires for the extra flexibility.
REPAIRING ALUMINUM WIRE CONNECTIONS
The best procedure to make your existing 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 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 to copper connection.
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 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 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 wire connectors that are rated for aluminum. These also cost more than regular push-in wire connectors.
Usually when an electrician works with larger sizes of aluminum 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 the old wire, oxidation.
Oxidation is no longer an issue with the newer aluminum alloys that are being sold and the use of ant-oxidant is no longer required for new installations.
Some of my posts on old house wiring might be of interest.