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I bought a cooktop which has 3 wires:

  • Black
  • Red
  • Green

The wiring in my home is 4 wires:

  • Black
  • Red
  • White
  • Bare

I saw the instruction for 3-wire to 4-wire connection, it states to leave the white neutral wire alone.

Is it safe to do so? Without neutral wire, how the circuit could be completed?

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5
  • 5
    Is that... a device box inside your cupboards? Because that's definitely illegal. As is NMD cable running outside a wall without protection.
    – J...
    Apr 6, 2022 at 11:59
  • Related: diy.stackexchange.com/questions/33602/…
    – Machavity
    Apr 6, 2022 at 12:22
  • 2
    It looks like your cooktop is using aluminum wires. Keep in mind only certain connectors are designed to connect aluminum and copper.
    – PJ8
    Apr 6, 2022 at 13:00
  • 1
    @PJ8 An appliance definitely won't be aluminum - it's tinned copper.
    – J...
    Apr 6, 2022 at 13:08
  • 6
    While we're looking at code violations: The box has a conduit clamp on cable. It should have a cable clamp and the other conduit clamp should be removed and a blanking plate installed.
    – FreeMan
    Apr 6, 2022 at 14:06

2 Answers 2

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14

You go by the instructions(if listed by UL/CSA). They can override local or NEC rules usually.

If a 240volt device (stove) does not use 120 volt (clocks, fans), it does not need to have a neutral wire.

So you can cap/wire nut the neutral.

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2
  • 11
    The "complete" circuit is between the red and black. For safety the grounds should attach not just to each other but also to the box as shown in your instruction sheet.
    – jay613
    Apr 5, 2022 at 22:40
  • 1
    The box even has a ground screw conveniently installed in the proper spot in the back
    – FreeMan
    Apr 6, 2022 at 14:06
2

Yes it's fine.

Current flows out through one hot conductor and back through the other (with the direction reversing frequently).

Traditionally in north America it was/is common to have equipment where the high power stuff was 240V, but the controls were 120V so a neutral wire was needed, but if the equipment is designed with 240V control equipment there is no need for a neutral.

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