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Will a NEMA 14-50 to NEMA 10-30 adapter work?

Hi all,

I recently moved to California, leaving my previous OpenEVSE in Canada with my parents who now also have a Volt. I built that one with a NEMA 14-50 connector, and they installed a supporting circuit in the garage. I now plan to build a new one for myself. I would again like to use the NEMA 14-50 connector as the main AC connector.

In the garage of the house I am renting, there is a NEMA 10-30 socket for an electric dryer. If I make a NEMA 14-50 to NEMA 10-30 adapter cable, where ground on the 14-50 is tied to neutral on the 10-30, will this work with the OpenEVSE? Current ratings are not an issue because a) I will set the unit's max current appropriately, and b) the Volt does not draw that much current. It's really just the lack of an actual ground connection that I am wondering about.



Will it work...most likely BUT... It is a violation of the NEC to use Neutral as a Ground and could potentially be unsafe. 

For clarity, is this because NEC explicitly requires 4-wire grounded circuits for EVSEs, despite allowing 3-wire ungrounded circuits in existing installations for things like ranges, dryers, cooktops, etc.?

I'll know more once I move in in a couple weeks, but my ideal solution is to have the receptacle replaced with a 14-30, if there is a ground present in the wire run. Then I can do 14-50 to 14-30, with appropriate current limit on the OEVSE. (Actual, my ideal solution is to have a new 50A circuit run to a dedicated outlet, but that's more $$$ for the landlord).

3 wire with 2 Hots and Dedicated Ground (not neutral is required) is okay. The Neutral could be shared and may to carry current, so it is not a good idea to tie safety/equipment grounds to a Neutral.

I was planning on building mine (the 50A 240V version) with a 14-50 plug but without the neutral pin so it can also plug into a 14-30 dryer plug (since the neutral is the keyed pin). There is no neutral wire going into the 240V 50A OpenEVSE.

This had been recommended on other forums. Is this not a solution for Scott?

I should have added to my other comment that I realize there is a safety issue if you plug the OpenEVSE 14-50 plug (without neutral pin) into a dryer outlet if you have not programmed the OpenEVSE down in current to limit the maximum draw. Well at least I presume it would just trip the breaker on the dryer circuit.

ok weird I don't see my first comment. Maybe now we will get a duplicate post.

I had said that I was planning on building my 50A 240V OpenEVSE with a 14-50 plug with the neutral pin missing so that it could plug into a 14-30 dryer outlet too as I had seen this recommended on other forums.

Is this not a solution for Scott?

There is no neutral wire going into the 240V only kits so no need for the pin on the 14-50 plug. The neutral pin is the one that is keyed and removing it allows the plug to fit into a 14-30 receptacle.

OpenEVSE does not require a Neutral but it does require a Ground.

Scott is using a NEMA10 - 30 which is missing the Ground.

Oh sorry was confused. I was talking about a NEMA 14-30 which is the typical plug for a dryer. He mentioned a dryer so I assumed 14-30 but now I see his post says 10-30 which is typically for welders or something.

NEMA 10-30 is typical of dryers in older American installations, likewise NEMA 10-50 for older electric range installations. Existing installations are grandfathered, but (if I understand correctly) new installations must be NEMA 14-x variants.

I am in the same situation as Scott, with a 10-30 plug in the garage for the dryer.  I've been using it with the Tesla Mobile Connector and its10-30 pigtail to charge the car, but would prefer to save it for when I really need something for the road.

I understand that using the 10-30's neutral wire as ground will probably work, but is not allowed by code.  Would it be better to instead connect the EVSE's ground to a cold water pipe, and leave the 10-30 neutral unconnected?  (The house pre-dates the use of plastic pipe, so it's all solid copper.) 


Quick update...  Talked to an electrician, and we observed that the Dryer plug in the garage is on its own circuit (as apparently it should be), and believe its neutral line is bonded to the UFER Ground at the panel.  So, electrically the neutral pin on the 10-30 plug is essentially, if not technically, the same as ground, and it should work as expected.


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