How to connect 3-wire appliance to 4-wire junction box

Question

I want to replace my old electric cooktop with a new electric cooktop. The new cooktop is 208/240V. It has 3 threaded wires: red, black, and green.

The metal junction box is 4-wire grounded. It has red, black, white wires and a bare wire grounded to a screw in the box.

Looking at my circuit breaker, the circuit running to this junction box is 120/240V.

Is this something I, not an electrician, can do? If so, is this the proper way to connect:

• Red to Red
• Black to Black
• Green (from appliance) grounded to the same screw as the bare wire (from the circuit)
• Cap off the white wire (from circuit)

Answer 1

That is correct wiring. You are in the very good situation of: Had 4-wire, now only need 3-wire. Far more common is either: "Had 3-wire, now need 4-wire" or "Had 3-wire that should have been 4-wire but grandfathered".

The only issue is current requirements. Depending on the size of the existing wires and breaker, you may be in any of the following situations:

• Everything OK as-is
• Wire OK but need to put in a larger breaker
• Wire OK but need to put in a smaller breaker
• Need to put in larger wire and a larger breaker.

Can't tell which of these 4 situations applies without knowing the specs of the new cooktop, the size of your existing wire and the size of your existing breaker.