prophet@umcp-cs.UUCP (07/10/84)
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Sorry for posting this here, but I lost the person's mail address and thus I
must reply to him here.
Regarding aluminum house wiring, my parents own and live in a house in
Richmond, Va. that was built in 1968. It, along with almost every other
house in the neighborhood, has aluminum wiring. There have been several
house fires in the neighborhood that are directly related to aluminum
wiring. The problems with aluminum wiring are as follows.
Back in the middle 1960's, aluminum wiring was developed because of a short-
age of copper. When used properly, aluminum wiring can be made safe. The
problem was, the electricians that wired the houses did not understand the
differences between copper and aluminum wire, and so the electricians used
aluminum in the same way they would use copper. This is a serious problem,
because aluminum has a higher coefficient of expansion than copper.
The electricians that wired the houses in my parent's neighborhood used
outlets and switches that have push-in holes instead of screws to connect
the wire. This is ok for copper wire, but totally unacceptable for aluminum
wire. What happens is this: When an electrical load is drawn through a wire
(any wire, copper OR aluminum) the wire tends to heat slightly. When the
electrical load is turned off, the wire cools down. Naturally, due to ex-
pansion and contraction, the wire tends to move a slight bit when heating
and cooling. Aluminum, with its higher coefficient of expansion, moves
quite a bit more than copper. This causes the connection to eventually
loosen a bit, especially with the push-in connector. This increases the
electrical resistance of the connection. As the resistance increases, the
wire begins to heat up more at the connection. As the connection loosens
still more, the connection begins to oxidize. Eventually, after many cycles
of heating up and cooling off, the oxidation builds up and the connection
loosens up enough to cause arcing at the connection. This is one of the
first signs of faulty aluminum wiring, when you notice your lights
flickering and static on your AM radio as the lights flicker.
We have had four separate incidents of circuit failure in our house due to
this problem. There have also been several fires in the nighborhood due to
aluminum wiring. To help offset the problems caused by use of the push-in
connectors, we purchased outlets and switches that are U.L. approved for
aluminum wire. These outlets and switches have screw-connections instead
of the improper push-in type. These screw type connectors, although not a
complete cure, helps to hold the wire more securely and prevents the
connection from loosening. I might add, that one of the times we had a
circuit failure, we found that one of the connections at an outlet had
heated up so much that the wire was melted!!!
To summarize, I would try to avoid a house that has aluminum wiring like the
plague. I do not know exactly when they stopped using aluminum wire for
houses, but I would play it safe and not buy a house with aluminum wiring.
To find out if a house is wired in aluminum, find an outlet or a switch THAT
IS NOT IN THE KITCHEN AREA and remove it. Examine the wire at the con-
nections. If the metal part of the wire (not the insulation!) is the color
of a Lincoln penny, then it is copper; if it is aluminum wire, it will be
silver in color. The law required back in the 1960's required that kitchens
be wired in copper regardless of whether the rest of the house is wired in
aluminum or copper, thus, don't examine an outlet in that area. To be safe,
examine several switches and outlets throughout the house.
Good Luck!!!
Dennis
--
Call-Me: Dennis Gibbs, Univ. of Md. Comp. Sci. Center.
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