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1234mom 06-29-2011 08:29 PM

wiring electric cooktop 4 wires to 3 wires
 
Have a new whirlpool G7CE3055 cooktop with 4 wires (black, red, white, bare) and 3 wire junction box (black, white, bare). Instruction say to wire black to black, Red to red, and cooktop white & bare to bare. The problems is that I don't have red at the junction box. what now?

AllanJ 06-29-2011 08:34 PM

You may not wire it up at all until you run a new cable up from the panel with white neutral, red and black for 240 volt hot, and bare or green for ground.

Most likely the white and black feed wires in the box are 240 volt hots in y our situation. Ground (bare) may not be used as neutral.

Jim Port 06-29-2011 08:39 PM

Your old unit must have been 240 volt only. The new unit has both 120 and 240 volt components.

1234mom 06-29-2011 08:49 PM

can the cooktop safely be wired with the black to black, white(junction box) to red(cooktop), and bare(junction box to white&bare(cooktop)?

1234mom 06-29-2011 08:55 PM

Quote:

Originally Posted by AllanJ (Post 676818)
You may not wire it up at all until you run a new cable up from the panel with white neutral, red and black for 240 volt hot, and bare or green for ground.

Most likely the white and black feed wires in the box are 240 volt hots in y our situation. Ground (bare) may not be used as neutral.

so what happens if it is wired black to black, white (junction box) to red (cooktop), bare (junction) to white & bare cooktop??

kbsparky 06-29-2011 09:07 PM

Can you post a picture of the wires in your junction box?

1234mom 06-29-2011 09:45 PM

Quote:

Originally Posted by kbsparky (Post 676857)
Can you post a picture of the wires in your junction box?


Unfortunately, at the moment, I'm not able to do so. What are you wanting to see or are looking for?

rbj 06-29-2011 09:49 PM

Quote:

Originally Posted by 1234mom (Post 676814)
Have a new whirlpool G7CE3055 cooktop with 4 wires (black, red, white, bare) and 3 wire junction box (black, white, bare). Instruction say to wire black to black, Red to red, and cooktop white & bare to bare. The problems is that I don't have red at the junction box. what now?

I agree with Jim, the mfr is suggesting non-compliant wiring. What could happen? The cooktop surface becomes an non-grounding surface with lethal shock capabilities from other surrounding non-grounding appliances. (I.e. toaster without polarized hookup)

mpoulton 06-29-2011 09:52 PM

Quote:

Originally Posted by 1234mom (Post 676836)
can the cooktop safely be wired with the black to black, white(junction box) to red(cooktop), and bare(junction box to white&bare(cooktop)?

It will function normally, and be unsafe. That's a code violation for good reason. The bare ground wire would be carrying current during normal operation.

rbj 06-29-2011 09:56 PM

what mpoulton said.:(

1234mom 06-29-2011 10:24 PM

do all new cooktops have 4 wires? the old unit had only 3 wires and thus was hooked up to the 3 wires from the junction box just fine. Why does this new unit now have 4 wires when it is just a newer version of the old one? And why does the mfg. instructions allow for connection to a 3 wire box? The problem, again, that I ran into and was confused about was the fact that I had no set of reds to connect? What do the colors of the wires mean? Finally, I'm in Alabama and how do I go about finding a licensed electrician that I can trust to run a new power supply from my breaker box?

1234mom 06-29-2011 10:25 PM

Quote:

Originally Posted by mpoulton (Post 676891)
It will function normally, and be unsafe. That's a code violation for good reason. The bare ground wire would be carrying current during normal operation.

that doesn't sound good at all.

rbj 06-29-2011 10:35 PM

Quote:

Originally Posted by 1234mom (Post 676927)
that doesn't sound good at all.

Even more exciting...that cooktop metal surface can be carrying current to the wire also.

rbj 06-29-2011 10:44 PM

Quote:

Originally Posted by 1234mom (Post 676924)
do all new cooktops have 4 wires? the old unit had only 3 wires and thus was hooked up to the 3 wires from the junction box just fine. Why does this new unit now have 4 wires when it is just a newer version of the old one? And why does the mfg. instructions allow for connection to a 3 wire box? The problem, again, that I ran into and was confused about was the fact that I had no set of reds to connect? What do the colors of the wires mean? Finally, I'm in Alabama and how do I go about finding a licensed electrician that I can trust to run a new power supply from my breaker box?

In the old days blk-red-wht did not use an equipment grounding conductor (EGC) The neutral was used as the grounding bond. In cases where truck stock only had blk-wht-bare, (I.e. SE cable) was substituted for the same 240V circuit with the bare as a neutral.

mpoulton 06-29-2011 10:58 PM

Depending on the specific cooktop, the previous version may not have required a neutral. Some do, some don't. In the olden days, a three wire connection with an INSULATED neutral was used for stoves and dryers. That old-fashioned connection did not have a ground, and the metal case of the appliance was connected to the insulated neutral instead. This posed a major problem if the neutral connection ever became loose - the metal appliance itself would be electrified. That's why this is no longer allowed for new installations. It was never permissible to use an uninsulated grounding conductor as a neutral, which your prior cooktop may have.


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