Aluminum Wiring

Hearing or reading things about Aluminum wiring and you are concerned?  Hopefully you find this information helpful.

Aluminum wiring was used to wire entire houses for a short time from the mid-1960’s to the late 1970’s during a period of high copper prices.  Aluminum is not as resilient as copper and expands and contracts more than copper wire, which leads to loose connections, arcing, melting and ultimately fire.  Also, Aluminum wire corrodes much more easily than copper wire, which causes the breakdown of the wire, particularly at its points of connection.   Many of the terminations to aluminum wire began to fail due to improper connection techniques (improper installation) and dissimilar metals having different resistances and difference coeffients of thermal expansion.  These connection failures generated heat under electrical load and caused overheated connections.

Breakage, due to improper stripping of the wires or over-tightening of the splices during the installation stage, has created further problems.  Insurance companies are wary of homes with aluminum wiring and most companies require a complete electrical safety inspection by a trained and certified electrical contractor before policies are sold or renewed.  Electrical modifications are usually needed and in some cases complete rewiring is recommended to reduce the risk of a house fire.

A device specifically known as CO/ALR (meaning copper-aluminum) was created that specified standards for devices intended for use with aluminum wire.  CO/ALR applies only to standard light switches and receptacles; CU/AL is the standard marking for circuit breakers and larger equipment.   CO/ALR devices (switches and receptacles) should be used in place of older receptacles that did not have the proper rating and Staback receptacles.

This alloy, when used with CO/ALR devices and aluminum-rated connectors, can be just as safe as copper wiring.  However it is extremely rare in branch circuit wiring, and most twist-on connectors in typical branch-circuit sizes, even those designed to connect copper to aluminum wiring, are not rated for aluminum-to-aluminum connections (an exception is the Marette 63 and Marette 65).  A home with aluminum wiring installed prior to 1972 probably has the older series alloy wire nuts/marettes that was designed for copper.

What Are My Options

Several upgrades or repairs are available for homes with aluminum branch circuit wiring:

  • Completely rewiring the house with copper wires
  • Pigtailing involves splicing a short length of copper wire (pigtail) to the original aluminum wire, and then attaching the copper wire to the existing electrical device.  The splice of the copper pigtail to the existing aluminum wire uses special wire buts, special crimp connectors, or special miniature lug-type connectors.
  • Refurbish devices with CO/ALR

Qualified electricians familiar with aluminum wire problems and repair methods should do any repairs. 

Even though it only was used between roughly 1965 and 1980, there are easily over 15,000 homes in the London area with aluminum wiring.  This means that 15% of the houses in London are 55 times more likely to have fire hazard conditions present.

It is estimated that there are over 450,000 homes in Canada that are wired entirely with aluminum wiring.  Studies confirm that these homes are 55 times more likely to have a fire hazard condition present than homes wired with copper.
Some Symptoms that may indicate aluminum wiring problems are:

  • Flickering lights that cannot be traced to a failing bulb or other external causes
  • Plugs that do not work even with the circuit energized
  • Unusual static on the radio, TV or computer
  • Switch plates and receptacle covers that are warped, discoloured or warm
  • Circuit breakers or fuses that trip for no apparent reason
  • Strange odor similar to that of burning plastic around switches and receptacles
  • Smoke or Sparking around electrical devices

In an effort to update the appearance of the home, some homeowners have unknowingly compounded the problem by replacing

dated plugs and switches with more modern looking Decora style device which are not rated for use with aluminum wiring (direct contact).  This has created an additional safety concern as the incompatible parts cause electrical resistance, resulting in overheating and possibly a fire.

Addressing Aluminum Wiring Concerns

1.Installation of CO/ALR devices only
This cost-effective method is a good start in improving the safety of your home’s electrical system.  It involves replacing all the receptacles and switches in the home with ones that are rated for aluminum wiring.  This takes care of both the metal expansion/contraction and corrosion issues.  Unfortunately this choice is limited to some older style, standard devices as the popular decorator style Decora devices and the new Tamper Resistant receptacles are not available in CO/ALR form.   This method alone does not address connections in lighting fixtures.

2.Copper Pigtails with Specialized Twist-On Connector
The most common method of addressing this problem is bridging a new copper pigtail wire between the existing aluminum wire and any electrical device.  This connection must be done using very specific twist-on wire connectors along with an applied anti-oxidant paste to increase conductivity and eliminate corrosion.

3.Copper Pigtails with Specialize Connector
The acceptable alternative repair methods of addressing this problem is bridging a new copper pigtail wire between the existing aluminum wire and any electrical device.  This connection must be done using very specific wire connectors 1) COPALUM – provides a permanent, low-resistance electrical connection to aluminum wire.   This repair eliminates the aluminum connection failure problems and still uses the existing installed aluminum wires.  This is a crimp that makes a cold weld.  This can be a cost prohibitive method though still cheaper than a complete home rewire.  2) AlumiConn – provides another acceptable alternative repair may be considered the next best alternative for a permanent repair.  This repair method involves using a setscrew type connector.

4.Complete Home Rewire Using Only Copper Wiring
Obviously this is the best and safest long-term solution to the aluminum wire dilemma.  For obvious reasons, it is also the most labor intensive and costly method.  Over all costs may possibly decrease when rewiring is coordinated with other major or structural renovations.

Never use on Aluminum Wire:

  • Common Hand-Crimped Connectors
  • Twist-on Copper Only Connectors
  • Receptacles or switches stamped with AL and a line through it.  These are incompatible with aluminum wiring