AL/CU connection

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  #1  
Old 01-21-07, 03:58 PM
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AL/CU connection

I'm talking a lot of greek here that I dont understand. Hopefully someone can help me out.

The 3 power lines are 220v 8 gauge AL (black, red, & bare). There is one 8 gauge line going to the oven. There are two parallel wired, 8 gauge lines going to the range. All three lines are on one 40 amp breaker.

The range came prewired with 12 gauge CU (red, black, white, & bare). I'm not sure of the wire type but it appears to have high temp insulation. The oven was prewired with 16 gauge CU (red, black, white, & bare). It also has the special insulation. The wires run through a flexible metal tubing pigtail (I don't know what it actual name of this tubing is).

The old range was wired directly to the AL lines. The old oven had a pigtail and the connection to the AL lines were made in a metal terminal box. When I removed the old range and oven, the range showed no problems (i.e. overheating wires). The old oven on the other hand, showed some serious issues.

The AL/CU connection in the terminal box were secured with wire nuts. The connection had overheated and one of the wire nuts had completely burned the insulation off. It's was just a matter of time until I had a fire or a direct short.

After researching the AL/CU issue, I understand why the wiring had overheating. The problem I have now is, what do I do about it.

I realize I could rewire the circuit but I want to avoid that if I can.

I saw some information about information (http://tooling.tycoelectronics.com/copalum_home.stm) about adding Tyco COPALUM AL/CU pigtails. This seems like a reasonable option although I have not checked into the costs.

Another solution seems to be a detailed wire nut installation (http://www.inspect-ny.com/aluminum/pl2p12.htm). Certainly the least expensive way to go.

I also considered using an aluminum Thomas&Betts Splicer reducer ASR0214-B2 which are rated for a AL or CU connection. I would make my own pigtail and use shrink tubing to insulate the connection. I dont know if that is code or not.

Anyway, I am looking for help on the AL/CU connection fix.

As a side question, why would I need two AL parallel wired 8 gauge wires that terminates at a 12 gauge CU connection?
 
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Old 01-21-07, 04:07 PM
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Wink

If it was my home and what I have seen aluminum wire do in many homes. Ld pull that D** wire out of there and run copper.

The AL/CU connection in the terminal box were secured with wire nuts. The connection had overheated and one of the wire nuts had completely burned the insulation off. It's was just a matter of time until I had a fire or a direct short.

Dont that say it all. Did they have any paste in them????
 
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Old 01-21-07, 04:29 PM
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Not sure about that wire nut site you linked. There is only one wire nut I know of that is rated for cu/al connections. Ideal purples and I'm not sure they make them large enough for #8 and I would still not use them.

cu/al rated split bolts, some 3M 88 tape and some 3M 33+ tape, a bit of No-ox and your on your way.

the wiring situation; not sure what you have. You had one wire running to the oven? and you actually list only one (although it was a paralled #8) to the range as well.


Try to explain that again. It makes no sense how you say it was hooked up.

from the size of the new equipment wires, are they gas? The wires seem quite small for electric units.
 
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Old 01-21-07, 05:06 PM
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1) The research I've done doesn't leave me with a whole lot of faith in the Ideal Purples. And you're right, they don't make them large enough for #8.

2) The range and oven are separate, built-in units.

There two #8 Romex (non-metallic sheathing) NM cables (with a red, black, and bare wires) going to the range. The cables are wired together so they can carry more current (like having a 4 gauge cable).

There is a single #8 Romex cable going to the oven.

I don't even have a gas line running to the house

3) Split bolt? Any why 2 different types of tape?
 
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Old 01-21-07, 05:25 PM
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Okay, I have the split bolt figured out. I'm still wondering why 2 different types of tape.
 
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Old 01-21-07, 06:20 PM
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The 88 is a rubbery thick tape. It fills and insulates well but does not adhere to itself as well as I would like to see. The 33+ (my preference) provides a tight smooth finish and helps protect the 88 from abrasion.

Now I could have recommended varnished cambric. That is an old electricians' I know favorite method for insulating. A pain to work with but very effective.

Now I see about the cables. I was seeing it as single conductors rather than a NM cable assembly.

Now that you have explained that, I still find it unbelievable to find #12 or especially #16 wire for the units.

To the last question of the first post. I dont know why there would be parralelled conductors as you describe but I will say that regardless what the manufacturer uses as far as wire size, the premises wiring must abide by the code which requires #8 for a 40 amp circuit.

Another problem with the intallation; you cannot parallel conductors smaller than 1/0 with a few exceptions, which would not apply to your situation.
 
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Old 01-21-07, 06:53 PM
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New to the market, but with better connections that the twist purples in my opinion
http://www.alumiconn.com/
Although still max of #10 wire.
 
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Old 01-21-07, 07:01 PM
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Now those I would have no problem with. They are simply a small terminal strip that is rated for either copper or aluminum wire. Too bad they aren't made large enough.

Actually I don't know why I tend to forget these but try these on for size.

http://www.polarisconnectors.com/black.html

actually the problem may be the small size of the appliance conductors, They may not accept that wide of a range of conductor sizes. Take a look though.
 
  #9  
Old 01-21-07, 10:03 PM
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Just to clarify things.

I was mistaken (go figure).

It was NOT a parallel cable set-up. There was a single #8 coming from the breaker box and terminating at the range. The second cable I was seeing was a daisychain (I think that is what it is called) to the range.
 
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