While preparing for painting in the laundry room I decided it
was a good time to replace the 36 year old, ceiling mounted,
drum style lighting fixture. When I unscrewed the base from the
ceiling and was preparing to remove the twist connectors
I was shocked (not electrically, but emotionally) when they
fell off in my hand. Probably due to heat, the aluminum wiring
had corroded completely through. Looking at the wire more closely,
I see other places where the insulation has baked and flaked off,
exposing bare wire. These are 14 gauge aluminum in Romex
Obviously, that wire has got to go. At the least I will have to get
attic and cut the Romex back from the fixture box and install another
box so I can splice in a new copper wire to feed into the fixture box.
Probably should look for some high temperature rated wire while
I'm at it.
Or, I could go one step further: Splice new copper to the cable
going down to the light switch, and then back up to the fixture box.
That would be a lot harder, as the switch is in an outside wall
at the edge of a fairly low pitched roof, making working room
extremely tight... laying on my belly in rock-wool insulation. But,
it would get rid of a bit more of the aluminum.
Before doing anything, I would inspect *all*
the fixtures and maybe *all* the recepts.
If there is one problem, there are likely many.
IOW, get a handle on the scope of the situation
you're looking at.
I was curious about this because I was working as a fledgling
residential electrician about mid point of the early AL wiring rage
(1970). Now that we know AL was misapplied at that time, I wonder how
all those homes I worked on (when I really didn't have a clue what was
going on) have fared. I did a search on "aluminum wiring hazard", the
third hit of 76,000, a commercial alum repair site, yeilded this:
"Aluminum Wiring was used in the construction of roughly 1.5 million
U.S. homes built between 1965 and 1973. According to a report
published by the U.S. Consumer Product Safety Commission (CPSC), homes
wired with aluminum wire manufactured before 1972 ("old technology"
aluminum wire) are 55 times more likely to have one or more
connections reach Fire Hazard Conditions than is a home wired with
copper. This problem only gets worse with time. The aluminum-wired
connections that fail tend to progressively deteriorate at a slow
rate, and after many years can reach very high temperature while still
remaining electrically functional in the circuits. A large number of
connection burnouts have occurred in aluminum-wired homes. Many fires
have occurred some involving injury and death."
Take this with a FWIW, they are in the biz of repairing AL
I haven't read everyone's comments yet, but I have aluminum wiring in my
house and when I added on to it I simply got some anti-oxidizing grease from
a local electrical supply store and used screw-connectors, not the twist
ones, to make all connections. The ceiling fan I added in had copper wiring,
so I had no choice but to make use of the aluminum.
Aluminum wiring isn't a problem so long as the connections to copper are
done properly and the wiring is rated properly for the load.
No electrical knowledge here, except to know not to stick a fork in a live
electrical socket. That said, I was on a job rennovation once where the
electrician was cussing at some unknown electricians which had years ago
wired aluminum to copper without putting this _compound?_ on the wires. The
wires _oxidized?_ and caused insulation to be bare. He said they were
supposed to put this compound when wiring aluminum & copper together. Maybe
someone can help you out on what this is. I'm not sure of the technical
terms are, in any case, I plead temporary insanity.
Git em, tiger!
Incidentally, if memory serves, copper runs two sizes smaller. So, if you're
pulling out 14 AWG, you can use 16 copper. I wouldn't bother in this case.
Just use 14 copper, and you'll be good.
The less aluminum wire in your house the better.
back in the day they used aluminum instead of more
expensive copper. they started noticing fire hazards due to people hooking
up aluminum wires to brass screws or fixtures. something to do with the rate
of expansion/contraction and the wires came loose from the fixtures. make
sure all your fixtures are for aluminum wiring. id even get a electrical
inspector in to look at it
14 AWG is the minimum size for installed wiring.
What's more important is having the correct size wire for the rating of the
overcurrent protection (fuse or circuit breaker). for a 15 amp circuit, that
would be 14 awg, for a 20 amp circuit, that would be 12 AWG.
It is always OK to use a larger size wire than required, and sometimes a
good idea to do so (large loads on a long circuit, etc..)
-- Welcome My Son, Welcome To The Machine --
Bob Vaughan | email@example.com |
There are 2 problems with aluminum wire.
Aluminum is very reactive and a clean aluminum surface will oxidize
rapidly. This is useful in that the surface winds up protected by a
thin layer of aluminum oxide and remains shiny. But the aluminum oxide
is an insulator which can increase the resistance of a connection and
cause a failure. This problem is solved using an antioxide paste, one
example of which is Noalox. The paste keeps oxygen away from the
aluminum. Some pastes also have (had?) particles of metal to 'bite' into
the aluminum wire. Aluminum is restricted is some uses, one I think is
some commections in damp/wet locations near the ground.
The second problem is that aluminum has a high expansion rate with
temperature - a lot higher than most other metals. As a result, when a
connection of aluminum wires in a joint surrounded by another metal
heats up, the aluminum expands faster and can be squeezed/ compressed.
This makes the connection a little looser with a little higher
resistance so it will heat up more on the next cycle of use. This can be
progressive and cause failure. The solution to this problem is to use
connectors and devices (switches, receptacles,... ) that are rated for
aluminum. This rating was developed after the problems developed using
aluminum for branch circuit wiring. Receptacles exist with a Cu/Al
rating. (I don't think any back-stab connections are aluminum rated.)
Likewise, wire nuts, split-bolts, etc sould be aluminum rated.
I would splice the aluminum wire to copper, with a small amount of paste
on the aluminum, using a wire nut listed for aluminum-copper, then
connect the copper to the end device.
Jag Man wrote:
Thnaks, Jim. I have lived in the house since 1972 so have visited most
wall boxes over the years... I think! Shortly after the bad news hit,
through and replaced all the devices that aluminum touched. That's
when I learned that all the lighting circuits are wired with aluminum,
and all the
outlets (except the switched ones) are wired with copper. Not
once did I find anything that looked like there had been any arcing or
until now. In my opinion, the problem is heat in ceiling fixtures.
were only 4: kitchen, the 2 baths, and the laundry room. And, this is
one of these to be replaced.
With help from this group, I recently ripped out all the aluminum in
the guest bathroom
going TO the lights and fan, replacing with copper. And yes, I used
twist connectors with the goo inside on the Al/Cu connections.
Like everyone else, I wish I could rip all the aluminul out, but that
a huge job. From the repairs and extensions I've done I know that all
cables are nailed to the studs 8" from the boxes at every wall box.
the wiring often dives through studs rather than just straight down
from the attic.
What that means is every wall box would have to have pulls down from
bypassing existing cables entirely. For interior walls I could almost
see myself doing that.
But what brings be back to reality is all the boxes in exterior walls.
have fire breaks, and more often than not are in the walls at the edge
roof. I've done some of that kind of thing for a sound system and know
stucco has to be broken through at the top and at the fire break. As I
said, a BIG job.
Anyway, thanks for listening, and I do appreciate the input!
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