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Is aluminum wiring a fire hazard even when no load is present?

Is aluminum wiring a fire hazard even when no load is present?


  #1  
Old 03-28-05, 10:47 PM
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Is aluminum wiring a fire hazard even when no load is present?

I recently acquired an old mobile home (I got it for free, can’t beat that price!) and I’m using it as a storage building; it of course has aluminum wiring as it was built in the ‘60s. I hooked the electrical up to it today, now I’m worried about the thing going up in flames at night while I’m sleeping.

I turn everything off when I leave (except for a small clock) so I’m just wondering if aluminum wiring will burn even if there’s no load on it? I wouldn’t think so, but I’m no electrician.
 
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Old 03-28-05, 11:53 PM
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Only way to answer that is if you have made a complete inspection of the wiring for damage. I would inspect all the accessable wiring..ie..receptacles. switches and lights .... make sure the wire nuts and wiring insulation does not looked burned or corroded. If it has been unihabited for some time then beware of rodent damage, they love to chew on wires. Do this carefully, with the power off of course, as aluminum isnt very friendly to a lot of bending and flexing. If any of it is 14 awg then it must be changed to 12 awg Aluminum or changed to copper. Aluminum Nm-b is darned hard to come by these days so changing to copper is probably the realistic answer. You may even want to change out the receptacles and switches to aluminum rated ones if they arent already all else being up to snuff.
 
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Old 03-29-05, 07:52 AM
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Most of the problems with aluminum wiring are poor connections. Poor connections only cause problems when under load. So by turning everything off, you are of course not 100% safe, but you have eliminated almost all of the hazard.
 
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Old 03-29-05, 10:03 AM
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I also agree on a careful inspection. Especially pulling ceiling-mounted light fixtures - very gently and very carefully so as not to stress the wire insulation - and visually inspect it. People often ignore the "60 watt max bulb" stickers in ceiling fixtures, and those 100 watt bulbs play havoc on the insulation of that aluminum wiring. Since it expands and contracts more than copper that flexes the insulation more, and I have often seen it cracked. Also, if the neutral (white) is more of a tobacco color, that's a good sign that it has been exposed to exessive heat, and the insulation is probably brittle. Beware of flexing it. If it is discolored but it isn't cracked, it should be OK. If you flex, stress or bend it, it will likely crack.

Also from this period, you may well find "back-stab" switches and receptacles. These are notorious for circuit failures (loss of power, not generally fire hazards). Replace any you find with Cu/Al rated switches and receptacles, and always terminate your wires on the screws, and tighten them very firmly.

Juice
 
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Old 03-29-05, 11:05 AM
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I inspected all the electrical when a painted a few weeks ago that was a perfect time because I had all the covers off.

I found a GFCI that was installed by the owner from the looks of it, when I took the cover off the wires and scotch-locks just fell into my hand they were so burned up. So I cut the burned wires off and just bypassed that outlet (there are a TON of outlets in this thing, it was used as an office building, so lots of computers were here). I bypassed an outside out let that didn’t look good also.

I discovered a very horrible connection in the wall (no scotch-locks, just pigtailed with electrical tape!!) which surprisingly didn’t burn, it seems someone decided to put in an outside light and didn’t do a very good job. All of the light fixture wires are cracking, they are braded copper going to aluminum, and the aluminum looks good though. I think I’m going to have to replace them.

Those are all the problems I found. It looks like they had an electrician come in and convert every receptacle to copper, when it was turned into an office. They all look very good.

I have to say, I’m kind of surprised there’s still a chance of fire with little current flowing, how can a wire still heat up with no load? Oh, and I have a question about those aluminum to copper pigtails, they look like standard yellow scotch-locks to me, there’s no anti corrosion grease in there either, same thing with the lights, can that be safe?
 
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Old 03-29-05, 11:27 AM
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No-ox compound is definitely a good idea on aluminum. The problem when there's no current draw is only if there is any damaged insulation or loose wires that could short-circuit, causing a spark. That could possibly happen with absolutely nothing turned on, unless the main service disconnect is off. Aluminum wire heating up when nothing is on is really not a problem in itself.

Juice
 
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Old 03-29-05, 01:37 PM
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Right, I forgot about short circuits. I'm thinking it would be best to put a main service disconnect on the ouside of this baby and flip the switch off every night.

Thanks for all the help everybody!
 
 

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