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Tuesday, October 18, 2011

Aluminum Wiring in Residential Installations

Aluminum wiring in residential buildings is very commonplace.  We at C&S Electric have worked with Aluminum wiring for many years, and continue to work with it on a daily basis.  We get questions quite often from home and business owners about it, and whether or not it is safe, or if it should be replaced, or what to do with it.
Many of our competitors will tell you that aluminum wiring needs to be replaced, and that it is unsafe.  However there are many alternatives to this that will save you a lot of money and hassle, that are just as safe and workable.

The following is an excerpt from the Electrical Safety Authority (ESA)

• Aluminum wiring was recalled because it is known to be a fire hazard.
• Aluminum wiring is no longer used for interior wiring systems.

• The Electrical Safety Code permits the installation of aluminum wiring.
• Adequate precautions shall be given to the terminations and splicing of aluminum          conductors;
• Aluminum wiring itself is safe if proper connections and terminations are made, without damaging the wire and devices approved for use with aluminum wire are employed.
• Aluminum wiring is widely used today for larger commercial and industrial feeders. Electrical distribution companies use it widely throughout their distribution systems including the supply service cable to most residences; in fact it may still be used today for interior wiring systems in residential homes as well as other structures. 

Aluminum wiring itself is safe and if proper connections and terminations are made without damaging the wire and using approved materials installed in accordance with the Electrical Safety Code and the manufacturer’s instructions, there should be no problems with the aluminum wiring installation.

Issues with aluminum wiring
Since January of 2003 the Electrical Safety Authority has received an increasing number of questions about the safety of aluminum wiring. In particular, purchasers or owners of homes built from the mid 1960’s until the late 1970’s with aluminum wiring are finding that many insurers will not provide or renew insurance coverage on such properties unless the wiring is inspected and repaired or replaced as necessary and this work is inspected by the safety authority, and a copy of the certificate of inspection is provided to the insurer. In some cases the insurer may require replacement of the aluminum wiring with copper wiring.  Check with your insurance company for their requirements.  Some homes may have a mixture of aluminum and copper wiring.
Reported problems with aluminum wiring have been related to the overheating and failure of aluminum wiring terminations. This is due to aluminum's tendency to oxidize and its incompatibility with devices designed for use with copper wiring. Warm cover plates or discoloration of switches or receptacles, flickering lights, or the smell of hot plastic insulation may evidence these problems.
Each home will be different and must be assessed on its own. It is highly recommended the homeowner hire a licensed electrical contractor who is knowledgeable in the special techniques required for working with and repairing aluminum wiring. The contractor should do an assessment, make the necessary repairs, and have the work inspected by the safety authority. The homeowner should obtain a copy of the Certificate of Inspection for their records and for their insurance company (if requested).
As mentioned above, where problems exist with aluminum wiring they are usually found at termination points. This necessitates the opening of all outlets (receptacles, switches, fixtures, appliance connections, and in the panelboard) and visually inspecting terminations for signs of failure and overheating without removing or disturbing the devices or wiring. There should be no signs of overheating such as darkened or discoloured connections, melted insulation, etc.
Where problems are found the damaged aluminum conductor should be cut back to remove the damaged portion and then the necessary repairs made.

Required markings for devices used with aluminum wiring replacement receptacles and switches shall be installed in compliance with the Electrical Safety
Code and as follows:

Receptacle (rated 20 amps or less) - "CO/ALR" or "AL-CU"
Receptacle (rated greater than 20 amps) - "AL-CU" or "CU-AL"
Switch (rated 20 amps or less) - "CO/ALR"
Wire Connectors (intended for use with combinations of either an aluminum conductor(s), a copper conductor(s), or both) - "AL-CU" or "CU-AL"
Luminaire (Lighting fixture or lampholder) - No required marking on fixture, however approved wire connectors are required.
Electric Heater -No required marking on heater, however approved wire connectors are required.  

Photo F1 – Required marking for devices used with aluminum wiring

Terminations of aluminum conductors
Rule 12-118(6) of the Code requires the connection of aluminum conductors to wiring devices having wire binding terminal screws, about which the conductors can be looped under the head of the screw, shall be made by forming the conductor in a clockwise direction around the screw into three-fourths of a complete loop and only one conductor shall be connected to any one screw.
Devices with “push-in” terminations shall not be used with aluminum conductors. An alternative to using copper/aluminum approved devices is to connect a copper wire “pigtail” between the aluminum conductor and the device connection screw of a device approved for copper only connections. Pigtailing also applies to the bond conductor, which is often overlooked. The wire connector used for the pigtail joint shall be marked as specified above.
Rule 12-118(1) states that adequate precaution shall be given to the termination and splicing of aluminum conductors, including the removal of insulation, the cleaning of the bared conductor, and the compatibility and installation of fittings.
Aluminum conductors are softer than copper and care must be taken that they are not nicked or cut, or crushed during termination. Nicks, cuts, or crush spots at terminations result in a weak spot that may result in breakage of the conductor or a hot spot.
Rule 12-118(2) requires that a joint compound be used with stranded aluminum conductor connections, but does not require it for solid aluminum conductors. Even though not required by the Code, it is recommended that bare ends of solid aluminum conductors be coated with approved joint compound.
Note: The compound is conductive and should be used sparingly and any excess compound should be removed.
Where pig tailing is used, Rule 12-3036 must be considered with respect to the minimum volume of box required to contain the existing as well as the new conductors and connections. Where there is not enough room in the existing outlet box, a surface mounted extension box may be required to contain the extra volume necessary to safely accommodate everything.
(ESA 01/05/09)


  1. Thanks for all your hard work on this site, I really enjoy reading it. Electrical Wiring

  2. Every year thousands of people are injured or killed from electrical shocks/contacts. They are exposed to dangers such as electric shock, electrocution, burns, fires, and explosions. The proper grounding of electrode system, conductors, equipment, and equipment conductors can help us in reducing the number of casualties. In order to understand grounding and bonding effectively, Contractor Continuing Education will certainly help you in understanding the best way of grounding and bonding per the National Electrical Code (NEC) 2008 standards.

  3. Hi there. Nice blog. You have shared useful information. Keep up the good work! This blog is really interesting and gives good details. Switchgears, Aluminium cable.

  4. Thanks for sharing this informative article on aluminium wiring, especially the myths vs. fact section.

    Jeff @ Electrical Contractors - A Grade Electrical

  5. This comment has been removed by a blog administrator.

  6. Nowadays it becomes general that every people will use aluminum in the wiring of their building or house. It is safe because aluminum conductors keeps you safe.

    Coiled Cables

  7. L & M Pedulla Electric is a family owned and operated company, the owners and employees of the company truly believe in taken pride in there work, and believe that family brings added value to the customers