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My cooktop has black, red and bare ground wires (brand new pre wired this way). Power supply has a neutral and no ground. Do I just leave it disconnected as shown? Is this connected correctly? Or should I greentape the unused neutral wire and connect to ground at panel and to bare wire from cooktop at juntion box. see picture.

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Whitestroke
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    It seems good if the cooktop does not require neutral. I would check for a good ground path back to the panel by checking voltage between a black(from the panel) and the box, it should read 120v. – crip659 Apr 26 '23 at 12:33
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    Where do you plan to connect the cooktop's bare wire? – Huesmann Apr 26 '23 at 14:19
  • I grounded it to the junction box. See picture. – Whitestroke Apr 26 '23 at 17:45
  • If your talking about the cooktop end? It came brand new wired in the cooktop with the conduit you see in picture with the black, red and bare ground. I didn't open it up at cooktop end. – Whitestroke Apr 26 '23 at 17:52
  • It's rather doubtful that the flexible metal conduit used for the supply satisfies the very limited conditions that make it suitable for grounding, and your installation was likely not code-compliant when installed. I would strongly recommend rewiring the supply to include an equipment ground. The connections as shown are correct, but they leave the cooktop without a proper ground. – kreemoweet Apr 27 '23 at 05:47
  • Could I green tape unused neutral wire green and connect at panel to the ground and at the junction box to the Bare Ground wire? – Whitestroke Apr 27 '23 at 07:03
  • Legally, no. But judging by the two black wires, it may be pullable conduit - you could remove the white wire and run a valid ground (if the conduit isn’t usable as ground itself). – nobody Apr 27 '23 at 12:25
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    No need to remove the white, by the look of things the fill is likely not an issue, so just pull in a green or bare. Then it's there when you swap appliances again and need it. – Ecnerwal Apr 27 '23 at 17:33
  • What is the breaker size on this circuit? What is the conductor size? What are the specified requirements for the cooktop? – Jim Stewart Apr 27 '23 at 21:31

2 Answers2

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You can’t re-mark or tape a neutral to turn it into a ground, per NEC 250.119:

Individually covered or insulated equipment grounding conductors shall have a continuous outer finish that is either green or green with one or more yellow stripes, except as permitted in this section.

The exceptions are for

  • low-voltage/low-power
  • conductors 4 AWG and larger
  • conductors inside multiconductor cable

Your situation doesn’t fit in these three exceptions, so you have to run a new ground wire. Luckily, you have a conduit, so it shouldn’t be hard.

Jacob Krall
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Note that if the conduit is intact all the way back to the breaker box, it is in fact a legitimate safety ground path, and you can ground the cooktop by attaching its ground wire to the box.

In fact, in your photo it appears someone has already done exactly that; the bare copper ground wire from the upper conduit goes to a screw attaching it to the box.

keshlam
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    It appears to be **flexible** conduit, so that only applies for something like 6 feet/two meters, as far as I recall. EMT, IMC or RMC don't have the length limitation, FMC does. But being (obviously, two blacks and a white) conduit, pulling in a green or bare should be possible. – Ecnerwal Apr 27 '23 at 17:30
  • Thanks, @Ecnerwal; wasn't aware of that restriction. – keshlam Apr 27 '23 at 17:42