# Hooking up 4-wire cooktop to 3-wire service



## Farmer Boy (Jul 18, 2010)

Home service provides a black, white and bare wire. The cook top I'm installing has a Black, White, Red and Green. The cook top has a downdraft vent built into it. Where does the red go? I assuming the green goes to the bare wire, is that correct? This is a used unit, it did not come with instructions. The GE model # JP385w0u1ww. 120/240 volt. The online instructions did not address where to connect the red cook top wire.

Thank You


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## jbfan (Jul 1, 2004)

The instructions should tell you how to wire the stove to a 3 wire service.
What is the model#?


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## Farmer Boy (Jul 18, 2010)

This is a used unit, it did not come with instructions. The GE model # JP385w0u1ww. 120/240 volt. The online instructions did not address where to connect the red cook top wire.


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## jbfan (Jul 1, 2004)

You proberly had one there before, but you have an illeagll install.
The proper wires needed from the panel today would be black, red, white and a bare ground.
When your house was built, it should be a black, red and white, not bare.
The instructions say to hook the black to black, red to red and the bare & white hook to the white from the wall.


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## a7ecorsair (Jun 1, 2010)

Are you using a recepticle that was connected to a stove or oven that was removed? If so, it was probably a straight 240 volt unit. Is your house on circuit breakers or fuses? Do you know was size breaker or fuse protects this receptacle?


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## Stubbie (Jan 7, 2007)

Are you replacing a cooktop or other cooking appliance and the 3 wire supply you are connecting to served that previous unit?

The used unit you have requires 120 volts and 240 volts. So it needs 2 hots (the black and red) a neutral (the white wire) and an equipment ground (the green wire). 4 wires total.

If the 3 wire supply was for a cooking unit your replacing with this GE cooktop it sounds like it was only 240 volts. Hence a black (hot) a white (used as a hot) and a bare equipment ground.

If the ground wire in the 3 wire supply cable you are calling 'bare' is a solid wire (not several stranded wires twisted together) then it sounds like you have a Romex or NM type cable for the 3 wire supply. 

If that is the case then ' *if* ' the replaced cooking unit was 120 and 240 volts you had the 'WRONG' cable connected to it.

The supply cable serving 4 wire cooking units that are 120/240 volts can be 3 wire *but* that 3 wire supply must be a type *SE* cable (link below) with a bare neutral/ground or the neutral in the 3 wire supply cable must be insulated just like the 2 hot wires. SE cables for the most part served ranges not cooktops. SE cables were rarely smaller than #8 awg.

In your case unless the 3 wire supply is an SE type cable (not NM cable) allowing a bare neutral/ground you cannot meet code by connecting to it with your replacement 4 wire cooktop.

The second thing is that if that 3 wire supply was installed for a 120/240 volt cooking unit after the 1996 NEC code cycle became effective in your area it would be the wrong cable period. All cooking unit branch circuit cables installed after that date for 120/240 volt units must be 4 wire (H-H-N-Grd).

After you figure all this out then you need to make sure the wiring and breaker is correct for the electrical needs of the used GE unit.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet273


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## HWConstruction (Jan 19, 2009)

You need to re-wire your service from the plug-in to the breaker or fuse box. The old service was 240 volts only. The new appliance is 120/240. The red and black wires are your lines (120v + 120v = 240v). The white is your neutral for the 120 fan and the green is your appliance ground.


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