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I currently have a 12A EVSE that takes either 120V or 240V and uses a normal three-prong (NEMA 5-15) plug. I am looking to install a 240V outlet on a 50A circuit breaker to use with this EVSE, but I'm wondering which receptacle to use with this new outlet. I've ruled out a NEMA 5-15/5-20 receptacle, so I will need an adapter to use my current EVSE for any outlet I install. Would it make more sense to install a 14-50R receptacle, a 6-50 receptacle, or some other type?

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    What make and model is your EV, and what sort of chargers can you get for it? – ThreePhaseEel Sep 13 at 0:43
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NEMA 6-15 and you're done

Outlets aren't that expensive. Simply fit the correct one.

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The third one.

If your wiring is 12 AWG or larger copper and your breaker is 20A, you can fit a NEMA 6-20 instead.

Now, noting this thing is dual voltage, the right way to deal with that is have it have a removable inlet (the way a PC does) that takes an IEC connector. Then you simply change the cord to what you're plugging into. However you can make a NEMA 5-15R to 6-15P cheater cord if you really want to. If someone finds a 6" long cord with a funny plug on it, that's a big fat hint to be careful what they plug in.

If you are thinking of wiring up a universal future adapter socket, you can't. What you can do is run 6/3 cable (or #8 THHN in conduit) to a large 4-11/16" square junction box. The large 4-11/16" square box gives you the room for big wires and splices. At this point you can install any of these pairs:

  • NEMA 6-15 receptacle with a 15A or 20A breaker
  • NEMA 6-20 receptacle with a 20A breaker
  • NEMA 6-30 or 14-30 with a 30A breaker
  • NEMA 6-50 or 14-50 with a 50A breaker

Note that except for a 15A receptacle on a 20A breaker, the receptacle size must always match the breaker size. And of course you can't exceed wire maximums.

  • Thanks! Why would you recommend installing a 6-20 and adapting to 5-15/5-20, rather than installing a 14-50 and adapting to 5-15/5-20? – palswim Sep 13 at 4:25
  • Yes, for many reasons. A 14-50 is not an option unless you install much larger wires and a 50A breaker. (Breakers MUST match receptacles amp ratings except a 15A receptacle is allowed on a 20A breaker only). Even then, it would fail to protect the 15A device. – Harper - Reinstate Monica Sep 13 at 4:41
  • Ah, I mentioned the 14-50 and 6-50 receptacles in the question, but I updated the question to make it explicit that I will install on a 50A circuit. – palswim Sep 13 at 5:07
  • @palswim OK, then you'd just need to change the breaker to match the receptacle. The smallest receptacles and breakers may not be willing to talk to a #6 or #8 wire, so you'd have to pigtail that. – Harper - Reinstate Monica Sep 13 at 5:11
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Eventually, I decided to wire the outlet as a NEMA 14-50 (hot-hot-neutral-ground) rather than a NEMA 6-50 (hot-hot-ground) because the I can re-wire to a 6-50 easily enough by capping the neutral wire and from my limited research, I found that more EVSE chargers used NEMA 14-50 rather than NEMA 6-50.

As far as adapting the outlet to my current charger, creating a NEMA 14-50 to a NEMA 5-20 homemade extension cord (cheater cable, as one helpful answer named it) did not pose too much difficulty.

My EVSE (E346031) only draws 12A. A short would trip a 20A breaker or a 50A breaker, so I had no fear about overheating and the extension cord. For any other EVSE, I would probably have to create a different extension cord.

  • I find it odd that EVSE chargers use 14-50s since they have no use whatsoever for neutral.... – ThreePhaseEel Sep 24 at 23:54
  • Be aware that a 14-50 to 5-20 cheater cord is not to code, because (1) an appliance cord designed to plug into a 5-20 outlet need only be capable of sustaining 20 amps before melting or catching fire, and (2) your breaker will only pop over 50 amps, which leaves plenty of room for a cable-melting fire-starting fault to occur. It's not common to see a fault draw 40 amps without being a dead short, but it is possible, and such a fault would almost surely burn down your house, so be careful and never leave a cheater cord unattended in use. – Glenn Willen Sep 26 at 18:04
  • (Incidentally, you CAN adapt 14-50 to 5-20 in a way that IS to code, by getting an adapter that has an appropriate 20A fuse or breaker in it. Although I can't find one, and I can find LOTS of the not-to-code kind. Home Depot even seems to sell them, which confuses me.) – Glenn Willen Sep 26 at 18:10

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