The high price of copper directly resulted in the use of aluminum wiring in many of the homes that were constructed between 1965-1973. This aluminum wiring was of the single strand variety, and though considered a safe choice at the time, was later discovered to have weaknesses. Aluminum wiring that is in good condition is acceptable for use. However, aluminum will break down faster than copper. Connections that have been neglected can become dangerous as they age.
Poor connections can cause overheating, which can in turn cause a fire should the temperature become too high. Because of this, some insurance companies will not insure a home that has aluminum single-strand wiring. When this type of wiring is noted by a home inspector, the home owner or potential buyer may be advised to check with insurance companies to ensure that the home can be covered by an insurance policy.
How dangerous is aluminum wiring? It was considered the cause of a fire that claimed two lives in New York in 1974. It was also labeled as fifty-five more times likely to be a fire hazard than copper wiring by the Consumer Product Safety Commission.
Dangers Associated With Aluminum WiringMany of the qualities of aluminum work to render it a material that is not the best conductor of electricity. Each of the following may cause loose connections, which may in turn cause a fire hazard. Consider the following:
- Aluminum is highly resistant to the flow of electrical currents. This means that aluminum conductors will need to be larger than copper conductors in order to handle the same level of amperage.
- Aluminum is less ductile than copper. It will not hold up well to frequent bending, and once the wire starts to break down it will resist the electrical current even more than it naturally would. This will cause overheating.
- Aluminum is subject to galvanic corrosion when it is exposed to moisture or comes in contact with some dissimilar metals.
- Aluminum wiring oxides at a much faster rate than copper. Air can cause the outside surface of the wire to to deteriorate, which in turn presents a fire hazard.
- Aluminum is a soft metal, and therefore malleable. This makes it very sensitive to compression. An act as small as over tightening a screw could cause the wire to be deformed and allow increased electrical resistance.
- Changes in temperature can cause aluminum to expand and contract. This can cause connections to degrade over time. This means that aluminum is not the best choice for many of the different termination types that are found on outlets and light switches.
- Aluminum allows more electrical current vibration than copper. Over time, this vibration may cause connections to become loose.
Does Your Home Have Aluminum Wiring?
The silver color of aluminum allows it to be easily be identified. In homes that were built in the early 1970's on, binding terminals that include aluminum wiring were labeled as CO/ALR, which stands for copper/aluminum revised. Wiring jackets may display the word "aluminum" or the letters "AL" may be stamped on the jacket. The date of construction may also be used as an indicator, with homes built from 1965-1973 being those that are most likely to contain aluminum wiring.
Wiring Correction Options
The condition of aluminum wiring will need to be determined by an electrician that has experience. Not all electricians will have worked with this type of wiring. According to the CPSC, there are two ways in which to correct aluminum wiring:
- Replace all existing aluminum wiring with copper wiring. While this is an effective fix, the cost to rewire an entire home will be high.
- Have copalum crimps installed on all connectors. During this process, copper wiring will be attached to existing wire branch circuits. This is done by attaching a special sleeve, and must be installed using a special AMP tool. An insulation sleeve will then be placed on the connector, completing the job. The cost per unit of repair is around $50.
The CPSC does not endorse the following methods. However, they may also be considered:
- Anti-oxidant paste may be applied to multi-strand wires, or wiring that is too large to be crimped.
- Pigtailing, or connecting a small piece of copper wiring to aluminum wiring with a connector of the twist-on variety, is another option. In order for this method to be effective, the wiring connections and pigtails must be completely reliable. The proper connector types must be used in order to not increase the hazard risk. The process of pigtailing will increase the connection numbers, all of which will need to be maintained.
- The use of CO/ALR connections may be appropriate for some areas. These will not include ceiling mounted fixtures or any appliance that needs to be permanently wired. These connections cannot take the place of permanent repair as they may become loose over time.
- Alumiconn may be used as a temporary fix. However, little history has been established in regard to its use. Additionally, alumiconn is often applied incorrectly.
- Replace devices and connections that are prone to failure with others that will work better with aluminum wiring.
- Flammable materials should not be placed near connections. Clear items away from aluminum based wiring connections.
A home inspection will reveal whether or not aluminum wiring is in place. Since it is a known fire hazard, home owners or buyers will need to make decisions in regard to how to deal with this issue.