plastic plumbing

DO NOT EVER MIX THESE TWO CONDUCTORS! An expolosion can result.

coaledsweat wrote:DO NOT EVER MIX THESE TWO CONDUCTORS! An expolosion can result.

Could you please expand on that. I have never heard of that. I know almost all residential service wire is aluminum to the breaker box but almost all wires out of the box through the house are copper. I think aluminum was used for a limited time in the 70's to wire all house circuits but was a major problem.

Back to PVC, My moms townhouse built in 85, had PVC, so the contactor saved $50. 22 years later the connection to the downstairs John busted while she was at work, flooding the downstairs just enough to ruin the new Hardwood floor installed 2 yrs before. That's how I got my starter wood for years! Contractor saves $50 and insurance co. pays thounsands! Now mom won't keep the toilet value open, real pain when I visit. You can keep that junk!

gaw wrote:

coaledsweat wrote:DO NOT EVER MIX THESE TWO CONDUCTORS! An expolosion can result.

Could you please expand on that.

If copper and aluminum wire are connected together in the same termination you are setting yourself up for a very dangerous situation. I have witnessed two fires and a 200 amp panel explode violently from this. They are not compatible under an electrical load. The more power involved the higher the danger potential.

So you are saying don't actually connect an aluminum wire to a copper wire? Say with a wire nut??

I know that aluminum is much more reactive with humidiity, and in a humid environment has pretty bad corrosion issues. Coaledsweat, I bet in your place that was a major contributing factor to the electrical explosion.

Most of us [ at least I do] think of an explosion as something flamaable, like gasoiine, or highly burnable like gunpowerder or other chemicals causeing an explosion. But if a circuit box is carrying a big load, and the corrosion inside causes a lot of resistance-heating, then the heat can blow the box apart, without any fuel other than oxygen and the fumes from the burning wire insulation...

Scary thought.... my place has at least four large distribution panels.... I guess I ought to inspect them ocassionally.

Greg L

.

coaledsweat wrote:

gaw wrote:

coaledsweat wrote:DO NOT EVER MIX THESE TWO CONDUCTORS! An expolosion can result.

Could you please expand on that.

If copper and aluminum wire are connected together in the same termination you are setting yourself up for a very dangerous situation. I have witnessed two fires and a 200 amp panel explode violently from this. They are not compatible under an electrical load. The more power involved the higher the danger potential.

I'm not sure I understand. The wire from the power company is aluminum like all overhead wire, right. The aluminum wire is screwed to the main circuit breaker which is copper, no? I always thought aluminum wire caused fires when it became loose and corroded and the insulation on it heated up and burned.

I guess explosion would not be the correct term, arc blast is what I think it may be called. You may find another name for it if you get burned from the plasma. Someone had pulled additional power off the feed at the top of the panel which was fed from the main with copper wire. They installed aluminum wire into the same termination as the copper to feed another panel. These two cannot meet in the same place and carry an electric load. At different ends of the same terminal block yes, in the same termination, no. It blew most of the panel apart and nearly off the wall. Termination blocks are almost always steel but may be plated with other materials. If they are copper clad, do not use aluminum wire.

Greg, as far as two wires with a wire nut carrying a small load there would not be a real dangerous situation. However, the connection is prone to an early failure.

http://www.inspect-ny.com/aluminum/pl2p8.htm

They do make a special wire nut for this application, I have no idea what the material is however.

OK, I was just trying to get a clear picture of what was OK, and what was a no-no.

So in big, high load connections: don't mix aluminum and Copper. Got it !!

Greg

The only time they can come in contact is when the whatever connects them is made to do just that, copper to aluminum.

The aluminum wiring used for service cable and used for large appliances still in homes today is not the same compostion as the aluminum used in the 60's and 70's that caused fires. The bad aluminum was a very soft type that would heat up and extrude after thousands cycles of heating and cooling from beibg under a load. It worked loose and arced causing aluminum oxide to form, making a poor connection and generating more heat until it actually caught fire, often without drawing enough amps to trip a breaker. I've seen many examples of this over the years. As far as an explosion, I don't know what happened in that panel but I don't think it was caused by just connecting copper to aluminum. I suspect some knucklehead wired something wrong, undersized, etc.
If copper is connected to aluminum, it must be with an approved device. Common wire nuts are nut aluminum compatible. There is a special wire nut called an Amp 95 that is compatible. There is also a new device called an alumiconn connector. That's what I recommend to my clients with aluminum wiring in their homes as a retrofit device.
www.kinginnovation.com/products/alumiconn.html

I guess I started quite a discussion with my innocent little quip.
I was referring to the 1970's aluminum wiring fad. I realize that service entrances are generally aluminum, I've installed them myself, mine here is aluminum. The metal mix is different that the branch wiring of the 1970s. Also the service entrance is a larger gauge, less prone to expansion then #14 or #12. When securing the feed to the main breaker, anti oxidant compound is first applied to the wire.

Just to add my 2 cents: I've been using Pex tubing for 5+ years now and I love it! I've used it for both domestic water, hydronic heat, and radiant heat installations. It was great before it was cheaper than copper and even better now. On the electrical side of things I have already witnessed arcing inside of a 200 amp service panel where the aluminum entrance cable was installed apparently without using the anti-oxidant paste and the wires were melted away to almost nothing by the time I saw it. This was in a heated basement in a house less than 10 years old.

mufwapo wrote: On the electrical side of things I have already witnessed arcing inside of a 200 amp service panel where the aluminum entrance cable was installed apparently without using the anti-oxidant paste and the wires were melted away to almost nothing by the time I saw it. This was in a heated basement in a house less than 10 years old.

Thanks, now I'm worrying that there isn't enough anti-oxidant compound on the ends of my service entrance wire and the lugs are not tight enough, so the next time I power up a high amperage piece of equipment the breaker box is going to explode.

Wood'nCoal wrote:

mufwapo wrote: On the electrical side of things I have already witnessed arcing inside of a 200 amp service panel where the aluminum entrance cable was installed apparently without using the anti-oxidant paste and the wires were melted away to almost nothing by the time I saw it. This was in a heated basement in a house less than 10 years old.

Thanks, now I'm worrying that there isn't enough anti-oxidant compound on the ends of my service entrance wire and the lugs are not tight enough, so the next time I power up a high amperage piece of equipment the breaker box is going to explode.

Oh man! The service line to my shop is under ground service cable (about 3/4 diameter total , strands combined) and I know for a fact there was no Anti-oxidant applied. It's been in place for 15yrs. but perhaps I'll apply some now, better safe than sorry.

Ed.A wrote:

Wood'nCoal wrote:

mufwapo wrote: On the electrical side of things I have already witnessed arcing inside of a 200 amp service panel where the aluminum entrance cable was installed apparently without using the anti-oxidant paste and the wires were melted away to almost nothing by the time I saw it. This was in a heated basement in a house less than 10 years old.

Thanks, now I'm worrying that there isn't enough anti-oxidant compound on the ends of my service entrance wire and the lugs are not tight enough, so the next time I power up a high amperage piece of equipment the breaker box is going to explode.

Oh man! The service line to my shop is under ground service cable (about 3/4 diameter total , strands combined) and I know for a fact there was no Anti-oxidant applied. It's been in place for 15yrs. but perhaps I'll apply some now, better safe than sorry.

I would, just to be safe. It will also give you a chance to inspect the bare ends of the line, and be sure the lugs are tight.
Just make sure to shut the power off first!