Residential Wiring -
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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.
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.
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
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
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.
You 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.
Replace 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.
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
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
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.
Once 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.
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 rooms.
In 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 switches and wire nuts to the new
ALR listed switches and purple wire nuts.
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
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
By: Donald Kerr
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Donald Kerr / Wiring Done Right
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