I have a NEMA 6-20 240 volt 20amp single outlet. It has three wire connections on it. Two hot and one ground. There is a four conductor (including ground) romex cable coming out of the box. What is done with the neutral white wire? I don't think it is used. Should it be disconnected at the service panel?

4 Answers 4


A NEMA 6-20 does not require a neutral. The devil is in the details. A NAMA 6-20 configuration is for a 240V, single voltage connection. If it were to have a neutral the configuration would be a dual voltage NEMA 14-20, 20A 120/240V.

If you don't need the neutral you can simply wire nut it off and leave it in the box.


Don't cut off the neutral wire at either end. You never know when you may need it. Just cap it off on both ends, then roll it up back toward where it enters the box.

NEMA 6-20 is a legit, modern connector.

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The NEMA 6-20 is exactly what it looks like: a slight rearrangement of the common duplex receptacle. It fits in the same junction boxes, uses the same cover plates, etc. It is typically used on 240V-only loads, which are loads generally too large to be powered by the limited 1440 watts continuous available from a common receptacle. The 6-20 can handle up to 3840W continuous, or 4800W intermittent.

If for Code reasons you need a 1-socket 6-20 receptacle, that's not a problem.

enter image description here src:GALCO

If you need the same power, but your machine also needs 120V power for some reason, the NEMA 14-20 will do the job. You can change to that at any time, just by connecting neutral at both ends. This is a bulky receptacle, and it won't come in duplex, and will struggle to fit in a 1-gang box.

  • Thanks for all responses. The single NEMA 6-20 outlet is for an electric car charging cord in the garage. It will not be used for anything else.
    – Rob Hylton
    Aug 15, 2018 at 19:44
  • What model of car uses this receptacle? Aug 15, 2018 at 20:21
  • 1
    @JimStewart Cars don't, chargers do. You can get chargers of almost any size (i.e. designed to make the most out of whichever circuit capacity you are able to provision, 120/15, 20, 240/15, 20, 30, 40, 50 ++ even 3-phase. Nothing like provisioning 16kw on three #12 wires! Many chargers are switchable so they can pull dial-a-load. Aug 15, 2018 at 21:20
  • How did you decide on 12 AWG cable, why not 10 or even 8 just in case you later want to ungrade to a higher current charging system? Or would this be just over providing? Aug 15, 2018 at 21:57
  • 2
    @JimStewart the charger's instructions called for a dedicated circuit. It's conduit and we could throw in 2 more #12 circuits in there, 9 wires is just within the fill and derate limit for 1/2" conduit. If I was doing an electric car charger kiosk outdoors with 3-4 fast chargers, I would have preferred the heavier wire and chargers rated to share a circuit. Aug 15, 2018 at 22:13

First - terminology - romex does not include the ground wire in it's count. Thus if your romex has 4 wires, and they are 2 hot, one neutral, then technically it's a 3+g wire and would be listed as something like 10/3 (assuming 10 awg)

That said, my understanding is that for new 220A installations, 4 wire outlets are now mandatory and 3 wire is only allowed for replacements.

If your box is feeding a 3+g to the outlet then you should install a 3+g plug. Your 2+g plug would be against code as leaving wires partially connected is not permissible, as I understand it.

  • 1
    NEMA 6 (hot-hot-ground) is perfectly allowed. It's NEMA 10 (hot-hot-neutral) that is disallowed except where grandfathered. Aug 15, 2018 at 15:55
  • can a 2+G wire be used from the service panel to outlet for this outlet?
    – Rob Hylton
    Aug 15, 2018 at 19:36
  • It could be that wiring with 12/3 + gnd would make this more flexible if later you would want to put in a receptacle with 2 hots and a neutral. Aug 15, 2018 at 20:29

I don't think it is either a code violation or a safety hazard to have an unused neutral conductor capped off in the box with a connection to any NEMA receptacle which uses only the two hot legs. You could disconnect the neutral in the panel, but some expert in the code could tell you whether that is required or advisable. I wouldn't do unless told that it should be done.

Changing to a receptacle with a ground presumably would not work because the appliances that would be powered with the NEMA 6-20 would have a plug which would not fit a receptacle with a neutral, I would think.

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