Cooktop Wiring


I want to wire a new Jenn Air Radiant downdraft cooktop. The wire from the breaker only has three wires (Black,White, and Copper). I checked the Black and White which were both "hot'. The directions say I need a 3 wire 120/240volt circuit). The cooktop has three wires in the connection box - balck, red, and white ( No copper). Do I connect the Black and Red wires from the cooktop to the balck and white "hot" wires form the breaker.? What do do with the white from the cooktop and the copper from the breaker? Thanks
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You don't have what the manufacturer requires. You need a three conductor with ground to feed it. The metal flex on the cooktop will be grounded by the bare wire in the cable. The neutral and two hots get connected color for color

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Would be OK to temporarly connect the white (I assume common) wire from the cooktop to the copper ground wire until I can get an electrician out to run a new conductor?
RBM (remove this) wrote:

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It'll work

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But is it acceptable to code; presumably there is a jumper to connect the frame to the neutral. On a dryer it would be fine, but they plug in. Is is also fine on permanently wired machines, or is that considered new work?

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Thanks for the information. I just hooked it up so the two hot wires (black and white) from the service are connected to the black and red wires coming from the cooktop. I then connected the copper wire from the service to the white wire from the cooktop. All seems to work fine. Should I jump from the copper/white wire connection to a screw on the metal frame box? It mayl be a while (maybe several weeks) before an electrician can come out if necessary. Is there a problem with this setup for a while? I think my previous cooktop had a similar arrangement where the common and ground where connected, although that top didn't have a fan. Thanks again for any advice.
Toller wrote:

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It will work, and in certain circumstances it's legal, but doesn't meet current code. In your case, the manufacturer specifically calls for a 120/240 volt three wire circuit, which you don't have. My guess is that this cooktop pulls more current through the neutral than the manufacturer wants to go through a shared neutral-ground.

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Look at page 3 of your installation manual under the heading "Electrical wiring information". If it indicates that the neutral is bonded to the frame, you can use the existing wiring provided the cable is large enough to carry the amperage of the unit

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Thanks RBM> The instructions do indeed say the nuetral is grounded to the frame. Does that mean I'm OK with the existing wires and it OK that I have the bare copper from the service connected to the white neutral from the Jenn Air. Is this OK for a permanent setup or do I still need to have a new line run. It would be nice to not have to bring the electrician out. Thanks again for all your time.
RBM (remove this) wrote:

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Yes, that's what I mean. Provided the ampacity of the line is large enough for the amperage draw of the new cooktop. The NEC requires new installations to have both neutral and ground conductors, but does allow the use of an existing three conductor feeder, and since the manufactures does not specifically require separate neutral and ground, you're good to go

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wrote:

240V wiring is supposed to have black and red. I suppose that electrician used what he had. It's that way in my house too. Just make sure the wires are big enough. If you want to be more correct, you could put a bit of red tape around that wire.

[But need to be opposite phases (240V [not 0V] between them).

Connect the white wire from the cooktop to the bare wire. Make sure ground is connected to neutral on the cooktop. This'll work, but there may be some rule about not using a bare wire as a current-carrying conductor.
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