I’m a helper and worked with an old time electrician and he did something a year ago that still troubles me. We wired a 50 amp 220 volt circuit for some heat pumps. he brought the wires into the panel, hooked them to ground and the breaker and left the white wire capped with a wire nut. He told me it will work fine and forget about it. Did we leave somebody with an open neutral? Is the ground wire the neutral now? Should I try and go back and fix this?
If the equipment in question doesn’t require a neutral (like much HVAC equipment), then the neutral isn’t floating, it just isn’t used/terminated on either side. I’m assuming you guys pulled in 6/3 or 8/3 romex, both of which have a #10 ground. Personally, I would have tied down the neutral in the panel side, but it isn’t a big deal, it’s just an unused wire at that point.
Remember that with 240v, you have 240v of potential difference between the two opposing 120v phase legs, and the opposition of phases are what complete the circuit all the way back to the transformer.
Maybe I’m missing something but 220 doesn’t need a neutral, just 2 hots. Maybe if you were wiring up a NEMA outlet with a neutral connection that would be bad, but a direct wire to an appliance sounds fine?
This is correct. Direct connection to a 220/240 appliance takes two hots – one each from opposite ends of the phase – and a ground. No neutral is required. (You may even find a sticker inside the wiring panel to the effect of, “Do not connect any neutral wire.” The mini split I just installed had one, for instance.)
Some people treat ground and neutral as interchangeable since in residential applications with only a single breaker panel they are often bonded at the panel anyhow. While you can get away with this in a variety of scenarios, doing so is not technically correct.
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It’s the same idea, except with two legs of single phase instead of 3 legs of three phase. A lot of HVAC equipment is centered around some kind of motor, and they’ll typically have some kind of transformer to derive control voltage.
Wow, thanks for the great explanations, I feel a lot better about it.
