connecting aluminum to copper wiring

Hi all,
I am remodeling my kitchen. I need to move the wiring for my range and I found oday that the wiring is aluminum. Here are the details:
House built in California in 1992. All of the wiring except to the range is copper.
Range wiring #6 aluminum, 3 conductors + gruond. All stranded. 2 conductors black, one gray, grounde bare, breakers 50amp.
House is 2-story with kitchen downstairs and range wiring between truss web.
So, What's up with aluminum wiring in 1992?
More important, I need to attach about 20' of wire to get to the rannge location. What sort of connector is approved for this?
I would like to use a new copper cable, but I want to know what type of connector to use. I know about the connection being in a box and accessible, etc. I just want to make the coppper/aluminum connection right.
Thanks much.
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It's still fairly common to use aluminum wiring on high amperage circuits. Much more common with main and subpanel feeds, it's occasionally seen on stoves or dryers too.
[Note, as far as I am aware, the Canadian CEC doesn't actually ban aluminum even with 15A/20A circuits, but given the concerns about it, few people will accept it, and some municipalities (ie: ours) add in code-overrides telling you can't use aluminum without prior approval from an inspector. This may apply to the US NEC also.]
It's safe enough because the connections at larger sizes are more forgiving, and since there's so few of them, the installer is more likely to spend the time to do it correctly.
Most problems with aluminum are on 15A/20A circuits (eg: general outlet and lighting strings) especially when the installer uses improper (often very cheap copper-only) outlets and/or push-in terminals. Both of which have always been against code for aluminum.


The most common way to do this is with split bolts (make sure they're rated for copper-to-aluminum and the wire sizes in question), anti-oxidant paste, and tape.
Probably best to obtain the materials from an electrical supplier where you can ask questions on how to use them, but you should find it relatively straightforward.
You may have difficulty shoving all this into the box tho. Good luck.
Consider yourself lucky that the existing cable is already 4-wire. The 1996 NEC amendments would probably require you to upgrade a 3-wire stove connection to 4-wire if you're extending it.
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Chris Lewis, Una confibula non set est
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Chris,
Thanks for the help. Now for 2 stupid questions:
1) Am I correct in assuming that 3 insulated conductors (black, black & light gray) plus bare ground is a 4 wire cable?
2) The 2 black conductors are the hot leads and the light gray is the neutral for the 240/120, right?
Thanks much.
snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote in message

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The answers to both questions are "yes" - _if_ the installer complied with code. The probability is very high that they did, but it wouldn't hurt to visually check the panel end of the circuit. The two black wires should connect to a pair of breakers[+]. The grey wire should be bolted onto a terminal block with other grey or white wires. The bare wire should similarly be bolted onto a terminal block with other bare wires.
The "block" shouldn't really be common to both bare and white wires, but often is - no big deal in a main panel. In a main panel, the "two blocks" are connected together anyway.
You can test it with a voltmeter too, but visual inspection is probably more useful in this context. The cable should be easy to identify - it will be larger than any other cable in the panel (except for the main feed or possibly a subpanel or an appliance that draws even more power than the stove - like an electric forced-air furnace or heat pump with electric heater strips).
[+] the breakers should be tiebarred together.
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Polaris: http://www.polarisconnectors.com/companyinfo.html Ilsco Nimbus connectors :http://www.ilsco.com / Similar connectors are usually available at Home Depot.
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This is Turtle.
Chris explained the changing over but i suggest that you stay with the same wire types and just run all AL. and use a juction box and keep all the wire the same to not convert over. Just a thought.
TURTLE
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As I understood the OP, the splice would be made in the stove's old electrical box used as a junction box. As that's probably a standard 4" square box, it'll actually be bigger than a standard J box.
Splicing aluminum-to-aluminum is effectively the same as splicing copper to aluminum (proper clamps, antioxidant grease et. al.).
[Even aluminum-to-aluminum doesn't allow him to use wirenuts I don't think. Only copper-to-copper splicing would.]
At best the OP'd potentially save a few dollars (in wire cost) at the expense of having the splice harder to do (stuff in stiffer/thicker wire), and the extension wire harder to find.
So, I don't think the OP would gain anything useful by extending the circuit with aluminum.
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box
This is Turtle.
It seem here you feel like just talking about something that does not make any difference.
TURTLE
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It does make a difference:
    - It'll be harder to accomplish (stuffing the thicker/stiffer      wire into the box).     - It increases the number of aluminum connections in the circuit and      attendant "be very careful" (ie: nicks, kinks) requirements.      Which many would prefer to avoid.     - Probably be harder to find the wire, and may be more expensive      (if you have to buy predetermined lengths from an electrical      supplier rather than a generic DIY outlet).
If he has aluminum wire already and he can get the splices into the box, then, sure, fine, go ahead.
But I _personally_ wouldn't spending _more_ effort (and possibly money) implementing an inferior solution. A superior result with _less_ effort (especially when there's minimal cost disadvantage at _best_) sounds like a better plan to me.
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this is Turtle.
i work with all types of wire and some 4/0 or so and when it comes to a #6 or #8 Al wire. they are real easy to work with. I would never have thought about not being able to get Al wire at the warehouses.
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So do I, but not nearly as much as you.

Sometimes the pros forget the DIYer experience.
The typical DIYer rarely handles anything larger than #12 copper, and will often find #8 copper a bit of a struggle, even when all they're doing is direct connecting to screw terminals on stove/dryer receptacles and pulling it through holes in studs and joists.
I remember my first exposure to pulling #8 Cu in a crawlspace well... and not so fondly...
I shudder to think of what most DIYers will encounter trying to stuff 4 split-bolted, taped and gooped #6 Al splices into a regular-sized stove receptacle box in a workmanlike manner. The technique and materials are unfamiliar - they're simply not used to it.
Getting half of the wires down to #8 copper, and getting the cable a little easier to pull is bound to make a significant difference for most DIYers.[+]
Al isn't banned here ("prior approval only" on municipal permits). Yet, I have yet to see _any_ DIY/builder warehouse[*] or hardware store stocking #6 Al here - indeed, _any_ size Al for that matter... While there probably are places here where you can get the cut lengths from rolls here, it'd be special order even in most electrical supply outlets.
For the most part, Al use is limited to electricians wiring lots of houses, where the cost savings (buying multiple rolls) makes a significant difference. For a homeowner extending a circuit a dozen feet or two, a few bucks difference (at best) isn't going to make up for the inconvenience of finding the stuff and installing it. You may find you spend more money on gas just getting the stuff.
[+] while of course this is somewhat larger, when my professional electrician friend installed a #4->#3 copper->Al splice for my 100A subpanel feed, the box he used was at least 3"x4"x6" - 2-3 times the volume of a typical stove receptacle box. From what I call from observing him, I wouldn't have wanted to try anything smaller myself, tho, he could have managed it I'm sure. [The splice was because the ganged 100A breaker he gave me from his "used parts box" wasn't rated for Al, but using Al for the 120' feed saved something like $200 over copper.]
[*] Ie: HomeDepot or Rona (Rona is HD's primary competition in Canada).
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Mr. Bill wrote:

Aluminum works great for stoves and feeder circuits. It's just a little harder to install properly, and generally only worth the trouble for long-run high-amperage circuits.
Look for split bolt connectors that are stamped "AL9CU". You can use AL9CU connectors for aluminum-to-aluminum or aluminum-to-copper splices. Use a deoxidizer black goop on the freshly stripped aluminum wire ends, and wrap the splices with electrical tape. I like to rewrap them with friction tape because it doesn't come loose, and even really good electrical tape can come loose on the ends if any black goop gets to the adhesive.
I don't know if friction tape is considered adequate insulation all by itself unless there's vinyl or rubber tape under it.
Bob
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On 2 May 2004 21:42:49 -0700, jmgreen snipped-for-privacy@hotmail.com (Mr. Bill) wrote:

By the time you buy connectors and such, why not just replace the whole cable all the way to the breaker box, and know you are safe. I was never fond of splicing high amperage cable, even if they are all copper. At a little over $1 per foot, isn't it worth knowing you are safe? Most likely less work too....
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snipped-for-privacy@my.com wrote:

I have a similar problem. All I would need to do is tear rip open about 40 feet of wall board. I think that might be a little more expensive and work. I assume he has the same situation. Unless we laid it undergound along the foundation.
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