If your stove uses no more than 3600 watts (as you mentioned) and that's at 220/240 volts AND there's nothing else on the circuit then the 10 guage wire ought to be safe. The reason I say this is that most electric water heaters use 4500-watt/220v elements and run them on 12 guage wire (which is a size smaller).
As to the breaker size - do the math. 3600 watts divided by 220 is a little over 16 amps; divided by 240 is 15 amps.
Question: if all surface burners AND the oven were on at once, would that go over 3600 watts?

Thanks for the quick response.....more clarification:

Well just to be clear. The documentation for the stove didn't say exactly how many watts it would be using. The documentation just said that you should have it on a 40 Amp circuit. And, since there is already 10 gauge wire there which is obviously capable of supporting 30amps I want to reuse what's there. I don't believe it would be safe to use a 40amp breaker with the existing wire.

I guess I'm wondering about whether or not the stove could ever consume 3600 watts. I mean is that even realistic.

What's the worst that could happen if the stove maxes out what the breaker will provide? The wiring should be rated to handle more than 30amps. The breaker should limit consumption to 30amps. Will parts of the stove just not work???

All parts of the stove will work properly until/unless the breaker trips.

If nobody else responds with precise numbers as to what current 10-guage wire can handle, you could stop into your local store that sells electrical wire and read the label on the 10-guage wire.
I think it'll handle a 40-amp circuit OK, but don't have the for-sure info. Assuming the 10-guage wire will safely handle the power requirement, you should be OK replacing the 30-amp breaker with a 40.

Remember, I'm assuming there's nothing else on that circuit.

[This message has been edited by rpxlpx (edited June 04, 2002).]

No need to assume. There is nothing else on that circuit. It is currently a dedicated circuit with 10-3 and a 30amp breaker.

I just found this table on the Web.
Wire Gauge Amps
14 15
12 20
10 30
8 40
6 65
With that in mind, your stove could use up to 7200 watts without max-ing out the 10-guage wire. (30 amps X 240 volts = 7200 watts) As to why they want a 40-amp breaker, probably just for a little extra margin.

I thought it worked slightly different from that.

Each hot line is still essentially only 120V. Thus when you multiply you would multiply 30 Amps X 120 volts = 3600W per line. I always thought that the applicances themselves kept the lines separate to power separate devices internally. For instance, an electric dryer would have one 120v line powering the heating element while the 2nd line would be powering the motor and the various other electronics inside.

My worry is still that the stove will use 1 120v 30Amp line to power the heating elements (which if they are all on might not be enough considering the instructions call for a 40Amp) and the other line to power the clock and other added functions the stove provides.

Most dryers use 120v for the motor and 240 for the heating element. Most electric stoves use 120 for the light bulb and timer and 240 for the heating elements, which are the main power users. Don't worry about the 120 in the stove. It's the 240 you should be concerned with. The 240 is obtained by using BOTH 120 lines combined.

[This message has been edited by rpxlpx (edited June 05, 2002).]

There's a mishmash of highly dangerous misunderstanding going on here.

NO electric range, apartment (20") or full (30") size notwithstanding, should be connected to anything less than a #8 wire. No. 10 wire is simply not heavy enough to carry the potential amperage an electric range can draw.

And a certain size breaker is not specified because it will make the range operate better; it has nothing to do with that.

Electrical conductors (wires) OPERATE a range and the breaker to which the wires are connected PROTECT the wires.

You can play with all the math you want to, but you can't escape the fact that a #10 wire is rated to carry a maximum of 30 amps and will not be protected by a breaker which won't snap until more than 40 amps hit it. A #10 wire will burn up (and burn your house down) before that 40-amp breaker even thinks about snapping.

And limiting each use to only one or two burners or just the oven will not bypass the potential for disaster. Burners burn out and when they do they can create dead shorts, causing uncontrolled amperage to run wild. When that happens, the only thing that can keep that wire from burning up inside your walls is a breaker rated at no more amperage than the maximum the wire is able to carry safely.

Apartment-size ranges require at least a #8 wire and full-size ranges require a #6 wire. You might get by with #8 and a 40-amp breaker on a full-size range, but it wouldn't be my choice.

Bite the bullet and rewire the thing for the size range you'll be connecting to.

Or forget the range and just get a hotplate for that #10 wire -- with a 30-amp breaker.

Unless, of course, you enjoy watching house fires.

EDIT: You don't necessarily have to rip out walls and cabinets. You can probably figure a route for surface-mount electrical conduit or the higher-priced Wiremold and run the new wire along baseboards, walls, etc., to a new -- and properly sized -- range outlet. And just leave the old #10 circuit for other uses.

[This message has been edited by HBB (edited August 20, 2002).]

Congrats, HBB. Your post says it all.

pOps, If the appliance calls for a certain min. or max. you must do it, for no other reason if you don't it will void your warranty. HBB is correct about rewiring. There may be a number of ways to do it without distroying your home. Do you have a basement? An attic? Is it on an outside wall?

rpxlpx....It would do you good to look up the word liability.