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Aluminium Wiring


Aluminium wiring came on the scene in the mid sixties (1960's) and into the seventies (1970's) which in part was due to rising copper prices. Compatibility issues became apparent with such items as outlets.

damaged outlet damaged burnt outlet damaged burnt outlet 

Aluminium has different expansion properties than copper when current runs through it, it requires a slightly thicker wire for the same current handling than copper does.

Metals that are in an oxygen atmosphere oxidize. Aluminium when it oxidizes creates resistance, where copper that oxidizes forms a conductor; increased resistance at the connections causes heat to build.

The combination of the oxidizing characteristics of aluminium + the the fact that aluminium has different expansion characteristics than copper + the fact that aluminium required a slightly thicker wire size to carry the same current as a copper wire all lead to some tragedies, and numerous house fires back in the sixties and seventies and continues on today if not properly installed. All this also contributed to connections such as on outlets becoming loose which also added to the chance of arcing and heat build up that resulted in numerous cases fires.

severly burnt outlet  The rise in insurance claims with homes that was wired with aluminium wiring made the insurance industry nervous to the point that some where refusing to insure homes wired with aluminium while others raised rates because of the higher risk of claims. 

As the years went by and the tragedies rose the industry did solve the issues with Aluminium wiring, They figured out among other things that they could not use the same type of connections that was previously used with copper. You also had to use a 12 gage wire to carry the load a 14 gage was able to with a copper wire. They came up with an anti oxidizing paste to reduce the rate of oxidization with aluminium wire. It is too bad we all had to learn that the hard way.

Considering the past history with Aluminium wiring I personally would want copper wiring in the home although aluminium wiring is still in use in many parts of the world.

Much has been learn about using Aluminium wiring since the sixties and seventies and the industry has learned how to make it safe.

Bellow is part of an article written by my former website partner Warren Goodrich who was a master electrician / inspector [who passed away a few years ago] which was written when NEC 2002 was in effect....

What to Do?

Now what to do with the wiring installed in the 70's that had inadequately compatible devices and connections is the question and is it safe.

In my opinion "NO" aluminum wiring is safe if installed in the 70's. However this aluminum wiring if 12 awg or larger can be made safe without rewiring your home, and this wiring may be made safe by you as minor repair that should be able to be done in a couple of weekends while watching your football games if you just knew what to do.

If you wish to rewire your home in copper that is fine if you have the money and time to do so. Most people don't nor will not have the money to do such a project.

If you wish to use your aluminum wiring that was installed in the 70's and want to make it safe to use then read the following.

YYou must replace any 14 awg aluminum wiring totally.

Replacing Aluminum Wiring

If you have 12 awg aluminum wiring or larger then start at one end of your home and this includes the attic or crawl space. In order to start this make safe project pick a room at one end of your home. Most likely a bedroom is the best place to get started giving you time to get used to what you are doing before you get to the heavily used rooms such as kitchens and laundry.

Receptacles and switches in the electrical market today if listed for use with aluminum wiring will have an ALR showing that this device is not only listed for use with aluminum wiring but the R shows that it has been listed after the testing labs upgraded to current requirements to be listed for use with aluminum wiring.

Start in that bedroom and remove each receptacle one at a time and install a new receptacle listed for aluminum wiring with the ALR initials. Read the instructions some connections require an antioxidation inhibitor to grease the connection to limit corrosion. Some devices do not want that antioxidation inhibitor. Read the instructions for making connections on each device and wire nut.

RReplace each receptacle and each switch in each room using either 15 or 20 amp switches and receptacles. The NEC allows 15 amp duplex receptacles and 15 amp switches to be installed on 20 amp wire. Remember that 12 awg aluminum wiring is only rated 15 amp and must be protected by a 15 amp breaker. Also realize that the receptacles in kitchens, nooks, dining, pantry, laundry, and bathrooms must be 20 amp rated wire. We will get to that subject later.

Next Steps

Now replace each receptacle and each switch in all living areas except the rooms listed above using ALR listed receptacles and switches.
Now go back into each room and drop your light fixtures and remove each wire nut one at a time so you don't mix up which wire goes to which wire nut.

Use ALR listed wire nuts. You will see this ALR rating on the wire nut box. They will be more expensive and will have grease already inside these wire nuts. These wire nuts should be purple in color and they are listed even for mixing copper and aluminum in the same wire nut but only if they are purple wire nuts with antioxidant grease already inside the wire nut.

Now anywhere else that has a junction such as attics and crawl spaces again replace all wire nuts with these purple ALR rated wire nuts.

OOnce you have updated your living area rooms and utility rooms and garage and attic and crawl space being anywhere there is a device or junction then it is time to work in the 20 amp required areas.

Anticipating Problems

We have a problem with aluminum wiring and 20 amp rated branch circuits. Your receptacles and switches are not designed to accept 10 awg aluminum wires that would be 20 amp rated. If you have 12 awg aluminum wiring in the 20 amp required receptacles (kitchen, dining, pantry, nook, laundry, and bathroom receptacles) then your 12 awg aluminum is too small to serve these />
IIn the 70's the bathroom receptacle circuit was often 12 awg aluminum 15 amp rated wiring. If it were me I would disable all bathroom receptacles using 12 awg aluminum wiring even if GFI protected. I would fish new copper 12 awg dedicated branch circuit to serve all the receptacles in all the bathrooms as a dedicated 12 awg 20 amp rated bathroom receptacle circuit. These bathroom receptacles are heavily used and the NEC today requires the above type wiring style in new homes 20 amp rated 12 awg wiring if copper.

Kitchen, Dining, and Pantry

In the kitchen, nook dining and pantry rooms I would delete and de-energize all receptacles fed by aluminum wiring. I would then split up these receptacles inter-mixing all the rooms with the same number of receptacles in each room on one 20 amp branch circuit but dividing all these receptacles so that you have three 20 amp 12 awg copper wires to serve equally the same number of receptacles. What I am suggesting is that a cook will not use receptacles in the dining nook or pantry while she or he is in the kitchen yet when dinner is served he or she will likely move that cooking equipment into the dining nook or pantry while serving dinner. This is an either or load design in dividing the load into three small appliance branch circuits serving the receptacles in that kitchen nook dining and pantry.

The light fixtures in the kitchen nook dining and pantry may still be 12 awg aluminum wiring. Just change the swtches and wire nuts to the new ALR listed switches and purple wire nuts.

Laundry Room

Now in the laundry I would again delete any 12 awg aluminum wiring serving receptacles in that laundry room. I would then run a 12 awg copper branch circuit 20 amp rated to serve all the receptacles in that laundry room.

Panel Connections

In the panel you should be fine with no concerns as to connections unless you have wire nuts. There has not been a history of failed connections in those panels. However aluminum wiring does have a tendency to become loose. In any panel open the panel and tighten each connection on breakers, neutral bar and grounding bar. You should find several that have worked loose inside that panel over the years.

Now you have updated and made safe your aluminum wiring meeting today's NEC Code standards.

If you feel you would like an expert to evaluate the aluminium wiring in your home make sure you get an electrician that has experience in aluminium wiring.

By: Donald Kerr
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