[billstl]

Hello,

I need to replace our GE profile glass cooktop because the glass itself shattered. I found a very similar used cooktop. However, the cooktop I'm taking out has 4 wires, black, white, red and bare copper. The one I'm putting in has 3; black, red and bare copper. Do I just match colors and go, ignoring the white? My oven is on the same circuit, wired into the same box.

Thanks,
Bill

[stanfortyman]

Do I just match colors and go, ignoring the white?

Pretty much. Just be sure to safely cap off the white wire.

Is the new unit the same draw as the old one?

[billstl]

Yes. The old unit is 220. The new cooktop itself has a plate that says 208y/120v, 60Hz, A.C. 3 wire on one line and 120/240v, 60Hz, A.C. 3-wire on the next line down.

[stanfortyman]

That is weird. If it really were a 120/240v appliance there would definitely be a white wire at the wiring harness. :confused:

[Handyman2007]

Pretty much. Just be sure to safely cap off the white wire.

Is the new unit the same draw as the old one?

I would not "cap off" the white wire. It should be connected to the bare copper. BONDING!!
Neutral (white) and Ground(bare copper) should be bonded.

[stanfortyman]

I would not "cap off" the white wire. It should be connected to the bare copper. BONDING!!!
Neutral (white) and Ground(bare copper) should be bonded.

WHAT?? Are you serious? NO, the neutral and ground should NOT Be connected!

If this really is a 240v "3-wire appliance you DO NOT need a neutral. You also NEVER (any more at least) connect a neutral to a ground anywhere outside the main panel.
I know what BONDING is, and this is not it!

Are you even an electrician?

[Handyman2007]

Hmmm, have you ever taken a look at the electrical wiring insde of an electric appliance... the neutral(white ) AND ground are Bonded within the appliance.

[Handyman2007]

That is on newer 4 wire appliances.

[stanfortyman]

They are bonded, or can be bonded, because of older codes allowing it. This allowance has been removed for several code cycles now.

Like I said, a straight 240v appliance does not even use a neutral.

[Handyman2007]

I will neither agree nor disagree with you but I have several schematics for appliances and newer 4 wire appliances Do have a neutral that is internally connected to ground.
Good Evening...
If I could add one to this response I would...

[stanfortyman]

I will neither agree nor disagree with you but I have several schematics for appliances and newer 4 wire appliances Do have a neutral that is internally connected to ground.
Good Evening...........
If I could add one to this response I would...

This is not a grey area.

For a 120/240v appliance such as a range or dryer:

An existing circuit can be left or used as is. The code change is not retroactive.

A newer circuit MUST be a 4-wire (one being a dedicated equipment grounding conductor) with the neutral and ground separate.

A straight 240v appliance does not use a neutral.

[donf]

To begin with, electricity has nothing to do with electronics. What the manufacturer does inside his box is totally outside the electricians domain.

For electrical problems, you can use a wiring plan, but not a schematic. Schematics are on the appliance side.

Now, please stop and think this through. Power is sent to a residence by either an overhead drop or an underground lateral.

You get three wires in. Two hots and one neutral. The "Neutral" is 120 VAC away from each Hot.

The previous statement that you do not need a neutral is correct if the device that is connected only use 240VAC (a water heater). However, if the device also requires 120 VAC drop ( as in a stove or oven) then you must bring the neutral over to the device.