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This question was originally going to be "my apartment doesn't have a washer or dryer so I have an extra 10-30P socket that I've been using to charge my car (for reference, an L6-30 plug that included an adapter to 10-30P) with for a year. How expensive would it to get a mechanical splitter that would let me switch between charging the car and adding a washer/dryer?" Looking into it more it seems I'm probably playing with a plug with no ground, only a neutral wire.

I've unplugged the charger for now, but what risks am I looking at by continuing to use the charger as is without the jerry rigged grounding out to a nonexistent appliance mentioned in that post? I'm handy and can follow directions, but am not an electrician; what should I do to make this safe?

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  • Can you turn the breaker for that receptacle off, open it up without unwiring the receptacle, and post clear photos of the inside of the box? This isn't great, since the exception in current Code that permits existing NEMA 10 stuff to stay in service may or may not have been applied correctly to your situation, and you're coming off a subpanel (vs. the main panel), but EV chargers don't need neutral for anything to begin with, so it's less severe than with a dryer, which actively is using the neutral as a current-carrying conductor Apr 28 '20 at 0:20
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    I find it odd that you have a NEMA 10, I understand the code to require the circuit to be fed from the service equipment, and apartment circuits are often are fed from a sub-panel. I would check the wiring behind the NEMA 10 to see if by chance somebody swapped the plug to match a dryer instead of changing the cord to match the building. Apr 28 '20 at 0:27
  • @NoSparksPlease -- the code only requires a NEMA 10 to be fed from the service equipment if the branch circuit was wired with SEU cable (i.e. with a bare neutral) Apr 29 '20 at 3:22
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Note that most EVSE chargers require a ground wire. Buy ones that don't and use GFCI protection, if you don't have a ground wire.

This is a rental unit. So any modification must be done with a) landlord authorization and b) by a licensed electrician. But here's what you're up against.

First, it's a Really Bad Idea to continue this in service.

The Hot-Hot-Neutral wiring is unbelievably dangerous. If there is any sort of connection problem with the neutral wire, it will electrify the chassis of the dryer. This should be taken out of service permanently ASAP for dryer use.

In fact, you should insist that any dryer you get is properly wired for a NEMA 14-30 receptacle, with the neutral-ground strap removed.

Note that the NEMA 14-30 is Hot-Hot-Neutral-Ground and is the "universal donor" cable.

The 6-30R to 10-30P adapter cheater should have the 10-30P end removed and smashed. If you want to put a 14-30P there, that is fine.

How easily can it be fixed up for EV use?

How easily you can convert it to proper EV use depends on how thick the stupidity got in the original installation. Several wiring methods were in play depending on age and carelessness. I'll discuss converting them to Hot-hot-ground operation. If possible I'll state how to convert to NEMA 14-30.

  • Obsolete Black Red White cable: you cannot use this hot-hot-ground. However you have two options:
    • You can retrofit ground and fit a NEMA 14-30.
    • You can install a GFCI breaker, fit a NEMA 14-30, and label it "GFCI Protected / No Equipment Ground" and use it for any plug-in loads.
  • SE cable with 2 conductors with a multi-strand bare mesh around it: can be treated either as neutral or ground.
    • Option 1: Treat it as neutral. Use the "GFCI Method" above to convert it to NEMA 14-30.
    • Option 2: Treat it as ground. Move it to the ground bar, and fit a NEMA 6-30 receptacle.
  • 10/2 Black white bare: This was never legal for a dryer and cannot be fixed. It can only be converted to hot-hot-ground by remarking the white wire black. Install a NEMA 6-30.
  • 10/3 Black white red bare: This was installed ready for NEMA 14-30. Swap and done.
  • 2 conductors plus a white in metal conduit all the way back to the panel - The metal conduit is ground. Fit a NEMA 14-30 and done.
  • 2 conductors + white in plastic conduit: Pull a ground wire and fit a 14-30.

Note that they do make dryers which do not require neutral, and can plug into a NEMA 6-30.

Further, if you need to do frequent interchange, the regular sockets aren't made for that. Go to the locking L6-30 or L14-30, which are.

Subpanel, if you have all 4 wires

If you have all 4 wires (neutral AND ground), you can install a subpanel and leave both dryer and EV wired up at once. You use a main-lug panel, and I recommend a Square D "QO" type 4-6 space panel because it's compact. It's expensive, but worth it, because if the inspector has a problem with 2 30A loads on a 30A feeder, you can slap on a $20 "generator interlock" and satisfy that concern.

The existing 4 wires (or 3 wires + metal conduit) come into the panel. Then you fit two 30A 2-pole breakers. One feeds a NEMA 14-30 for the dryer. The other feeds a NEMA {14 or 6} -30 for the EVSE. If you run them both at once, it will trip the breaker, so don't :)

Generally, EVSE's need a dedicated circuit. If you need to do this often enough to potentially wear out a socket, you should really be dedicating a circuit. The "Subpanel" method will get that done.

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  • Using a EV charger on a ungrounded GFCI protected circuit will conflict with the installation and operating instructions included with many EV chargers. This would violate the (UL) Listing. the NEC, and any product warranty. images-na.ssl-images-amazon.com/images/I/91iSxyhnxVL.pdf Apr 28 '20 at 14:26
  • Thank you Harper, and all others! This is definitely something I am not going to touch (literally) beyond unplugging it, and your advice will be very helpful to my (perfectly fine) landlords. I only moved in recently, and the previous tenant had been here over ten years, so it's probable the owners didn't know about it and weren't entirely stupid, just unknowing. Thanks again, and stay safe!
    – LafinJack
    Apr 28 '20 at 17:01
  • Would them getting a dryer that doesn't use neutral (if the user manual is anything to go by, the Blomberg heat pump dryers don't need neutral at all), putting a 6-30P cord on it, and switching the receptacle to 6-30R make it OK? Apr 29 '20 at 2:42
  • @NoSparksPlease Good point. Worth a warning. My advice would be not to pick one of those. Apr 29 '20 at 3:18
  • @ThreePhaseEel Really good point - I did not know about those. Now that I think about it, I do have a couple concerns with plug interchange on a daily basis. Apr 29 '20 at 3:23

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