I think I need to splice 220V...

Hi,
I'm in the process of replacing a gas stove with an electric oven and separate cooktop which has me playing with 220V current and I've got a couple questions... I've got a 220V circuit that was run when the house was built but never hooked up since we were using gas. I'd like to use this for the oven, but it's not quite long enough. I'm hoping somebody can help me answer the following:
1. Can I splice the existing 220 line to another 10 feet of cable to make it reach? 2. Do I need a special junction box for this or can I use the same ones I use with 110? 3. The wires are quite large. I can't imagine I'd be able to twist them with the wires from another cable and put on a wire nut like I've done with 110 in the past. How do I join them together? A butt splice? 4. The oven manual explicitly states to attach it to copper wire. It appears, though, that the existing wire is aluminum. Do I need to replace the entire wire? Can I splice in copper and be fine?
Thanks, -Doug
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It can all be done. However... You are dealing with big amperages and aluminum wire, and don't seem to know what you are doing. That is a potentially bad combination.
I would have an electrician look at it. (Though someone here will probably tell you exactly how to do it. Please get it right.)
Another issue (which you will probably ignore also) is that if the existing cable is more than 8 years old, it is probably 3 conductors. You need 4 conductors to do it legally. I won't get into the issue of whether you need 4 conductors to do it safely; it is done to death here about every month. There is no way to get around this; you have to replace the cable.
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Unless he has no clue what he is doing, I dont think he needs an electrician. Just spend the money and get new cable. Sure it may cost around $2 a foot, (or less if you buy a 50 foot roll). But is your home and life worth the $100 or less that you spend?
Yes, you splice in common boxes, but large ones. But if you splice CU to AL, you are asking for trouble, and the only safe method to splice is with split bolts and a special taping method. Just replace the cable and be done with it. You might someday find another use for that old cable too, such as hooking up an elec. water heater, so dont toss it.
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Doug Neumann wrote:

You need to determine whether your stove requires a neutral connection (for the oven light, ignitors, etc.). It probably does. You need to determine how many conductors are in the existing cable. If the stove requires a neutral connection, and if the existing cable only has 2 hot wires and a grounded wire, you cannot extend it and keep the current configuration.
Do the old wires terminate in a big brown receptical? Even if there are only 3 wires, you could still use it if you attached an extra-long cord to the stove and plugged it into the old outlet. (This is unlikely to be acceptable because it will be hard to hide the long cord, but I thought I'd mention it)
If the wires are old enough, they might be tinned copper and they just look like aluminum.
In the unlikely event that you do have 4 conductors, you can splice onto them, and you can even splice copper to aluminum. But you have to use a really big junction box, and the right connectors, and you have to prepare the ends properly if they are aluminum.
If it were me, I would probably run a brand new aluminum cable (#4 or #6 aluminum type SER cable) from the breaker panel to stove and install a NEMA 14-50R receptical right behind the stove. Then put a 4' or 6' cord-and-plug set on the stove. This will come in handy later when you need to remove or replace the stove -- you can just unplug it. And any stove can be made to plug into a 14-60R outlet.
Bob
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Yes.
Standard 4" square boxes (not octagonal) are adequate for a simple junctin.

There are wirenuts suitable for this size.

You _can_ splice copper to aluminum, but it's a lot of fuss. You won't be able to use wirenuts (either special crimp-ons, or U-bolts) and de-oxidant grease, tape, possibly a bigger box. If running a new circuit in all copper isn't _real_ hard to do, do that.

... legally. It'd _work_, but you shouldn't.

You shouldn't have ;-) It'd _work_, but it's not legal (there are code max-lengths for cords to such devices (at least here), and you can't plug in a builtin oven).

See above.

You'd have to finesse the oven's "requirement" for copper wire. I don't know where the instructions mean "no Al WHATSOEVER", or, "Al is fine if you connect properly, but copper is so much easier, don't give yourself an unnecessary headache".
For an oven, the price differential isn't that much, so I'd wire install a new branch with copper. Unless that would be a major expense (like major wall repair).
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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Chris Lewis wrote:

Oops. And I missed the part about it being built-in. :-/

Probably means the terminals are only listed for copper. If you hardwired it, you would need all copper wire. If you use a cord and plug, the cord with have copper or brass terminals already installed, and it's none of the stoves business what kind of wire you used for the receptacle.

You're probably right. Definitely right if he's gonna hard-wire it. If he uses a cord/plug/receptacle to attach, AL might make sense. (I just instinctively think AL wire for feeder circuits and stoves, copper for everything smaller, and the actual service wires can go either way.)
Best regards, Bob
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I should mention that you can always pigtail aluminum to copper IF you do the connection correctly.
My 100A subpanel is pigtailed - obviously the electrician didn't think it was a good idea to run #3 Al into the "used" 100A dual breaker he had installed in the 20+ year old Commander main panel. So there's a 4x6x6 box sitting beside the main that simply splices a short chunk of #2 copper to the panel.
But on the other end, the Al connects direct to the (then) brand new Seimens subpanel.
--
Chris Lewis, Una confibula non set est
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