The U.S. Consumer Products Safety Commission
estimates that the likelihood of having a
connection reach fire hazard condition in a
house wired with "old technology" aluminum
wiring (manufactured prior to 1972) is 40 to 50
times that of a house wired with copper wire.
There is genuine increased fire risk with such a
home and the homeowner should make modifications
to the house wiring system to lessen the risk.
Number of Affected Houses:
It is estimated that there are approximately 2+
million homes across the U.S. that are "aluminum
wired." These are predominantly tract built
homes constructed between the years 1965 and
1972.
Distinguishing the Wiring Type:
The wiring that is of concern is the LOWER
BRANCH wiring that distributes power to the
plug-in receptacles, the switches and lights,
the kitchen countertop plugs and the minor
appliances such as disposer, dishwasher, furnace
and washing machine. This is single strand wire
and solid aluminum. (This wiring is
distinguished from copper clad aluminum and all
others.)
There are differing generations of aluminum
single strand wire but the solid aluminum wires
are all considered essentially the same, higher
risk. Most modern houses employ some aluminum
wiring. Entrance cables from the street and
through the meter to the distribution panels are
most often aluminum as are the heavier 240 volt
circuits that feed the major appliances in
homes. An "aluminum wired" house is
distinguished by the existence of single strand
solid aluminum general lighting and minor
appliance wiring.
The Idiosyncracies of the Problem:
The problem is not with the wire itself, it is
intermittent hot connections where the wires
join together or connect to devices. The reasons
for this are not absolutely known but seem to
center on the following factors:
1. Aluminum wire has a higher coefficient of
expansion than copper and expands more when
current passes through it. This can contribute
to loosening at the connections.
2. Aluminum wire must be slightly thicker than
copper to carry the same loads and this sizing
difference may have contributed to loosening
connections in early applications.
3. Metals in an oxygen atmosphere oxidize.
Copper that oxidizes forms a conductor while
aluminum oxide is a resistor. The resistance at
the connections causes heat to build.
4. Unlike metals which connect can cause an
oxide build as well and this may have caused an
increased difficulty when aluminum wire was
joined to devices intended for copper wire. The
oxide added resistance.
5. The problem seems to increase as time goes
by. This would seem to be due to increased
loosening and oxide build.
Danger Signals:
Here are some symptoms that you may have
aluminum wiring in your house or that your
aluminum wiring may have connection problems.
1. Flickering lights.
2. Unusual static on radio or TV.
3. Reduced TV picture size.
4. Arcing or sparks coming from switches or
receptacles.
5. Cover plates on switches or plugs hot/warm to
the touch.
6. Plugs and lights that don't work. Dead
circuits.
7. Circuit breakers that trip for no apparent
reason.
8. Arcing sounds within main distribution
panels.
9. Melted insulation on conductors near
connections.
10. Burning plastic odors near plugs or switches
or lighting.
11. Smoke from switches or plugs or junction
boxes.
12. Light bulbs that burn out quickly or shine
unusually bright.
Making Aluminum Wiring Safer:
A variety of modifications have been practiced
over the years but only the "COPALUM" method is
considered acceptable by the U.S. Consumer
Products Safety Commission.
1. The various switches and plugs can be changed
to those carrying the label, COALR, which is a
more compatible metal to connect aluminum to.
This is relatively inexpensive (about $6.00 to
8.00 per device) but it does not address the
loosening potential or those connections made
within junction boxes or within the main
distribution panel itself.
2. Pigtailing with copper wire attached with
SCOTCHLOK connectors and PENATROX A antioxidant
compound. The aluminum wire is attached to a
short section of copper wire with a compatible
wire nut and reattached to the device. Both the
aluminum and copper wires are first cleaned with
an approved antioxidant compound. This method
addresses all of the connections and is somewhat
more expensive. ($7.50 to $9.00 per
connection.)
3. Crimp connecting with the AMP COPALUM
connectors. This method is similar to the above
method except that a cylindrical device is
placed over the wires and then is crushed to
cold weld the wires together permanently. This
method is the US CPSC accepted one and is
considered the highest quality risk reduction
method available. Because it involves more time
and equipment, it is more expensive. The cost is
approximately $12 to $15 per opening or
connection.
Warning: Working with older aluminum wire is
more difficult than working with copper wire. An
inexperienced electrician can do more harm than
good. Aluminum wiring safety retrofits are best
left to specialists.
For further information on this subject we refer
you to:
"How to make your aluminum wiring safer."
Technical Dynamics Publishing Department
402 Riverside Drive
Pasadena, MD 21122
"Repairing Aluminum Wiring"
U.S. Consumer Products Safety Commission
Washington, D.C. 20207
8006388326