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NEMA 14-50 outlet on a 30 AMP outlet

NEMA 14-50 outlet on a 30 AMP outlet

I am a newbie here and not an electrician - so please forgive my dumb questions.

I need a couple of queries answered, I thought I'd ask before going to the electrician.

1. Can the NEMA 14- 50 outlet run on a 30 AMP outlet? I understand that it slow charging at 24 AMPS, better than 4 miles /hr on a regular outlet? Are there any other concerns?

2. This outlet is shared with drier. I am not sure if I can use the unused outlet. The conduit comes in and splits up in the two boxes. One is used by the drier, and the other one is closed (un-used).

I know them sounds dangerous. But, I am out of breaker spots in my box, and my main is on the other side of the garage. Adding a separate breaker box or adding in from the main would cost me a couple of thousands. And moreover, if an electrician has provided an additional outlet box, I would assumed it can be used.

Yodrak. | 7 mars 2019

I won't comment on having two 30 amp devices on one 30 amp circuit, it seems you already know to not run both at the same time, but why don't you leave the unused outlet as it is and get the appropriate 30 amp adapter for your charging cable?

TeslaTap.com | 7 mars 2019

No, it is not safe to instal a 50 amp outlet on a 30 amp circuit. You could install a NEMA 14-30 on a 30 amp breaker and get the Tesla 30 amp adapter. Code only allows one high power outlet per breaker. You can't just stick two 30 amp outlets on the same circuit. The idea is they don't want any scenarios were you can blow the breaker, which would occur if you charge the car and run the dryer at the same time. While you might know not to do this, someone else may not be aware of the improper configuration.

Here's a bit more on all the outlets available: https://teslatap.com/articles/home-charging-wiring-guide/#connectors

In some cases, you can add a quad breaker in place of two single breakers. The quad could be two 30 amp 240 VAC circuits, take the place of a single 240 VAC double breaker.

Perkins53 | 7 mars 2019

Don’t know why you would have two receptacles on one 30amp dryer circuit. (Not an electrician). You wouldn’t want to run the dryer with anything else on the circuit! If you are charging your car ,a 30amp circuit is great if your daily total commute is under 100mi. And you have the proper Tesla plug for that receptacle. To be safe I would get rid of that 2nd receptacle so that only one thing is plugged in at a time.

esklaw16 | 7 mars 2019

You can use a NEMA 14-50 receptacle on a 40A circuit, but not a 30A. You're correct about the risk of this setup, but there is a solution. What I'd do in your case is install a transfer switch to make certain that the dryer and EVSE are never used concurrently. Or a device like this: https://www.bsaelectronics.com/collections/dryer-buddys/10-30

esklaw16 | 7 mars 2019

One note. If you use a transfer switch, you'll have two thirty amp receptacles with the switch ensuring that only one can be used at a time. Assuming you're talking about the corded mobile connector, you'll use the Tesla 30A adapter (NEMA 10-30 e.g.) to connect to the receptacle.

esklaw16 | 7 mars 2019

One note. If you use a transfer switch, you'll have two thirty amp receptacles with the switch ensuring that only one can be used at a time. Assuming you're talking about the corded mobile connector, you'll use the Tesla 30A adapter (NEMA 10-30 e.g.) to connect to the receptacle.

sherbkarki | 13 mai 2019

I am just getting my M3 in a few days. Since my home was built in 2016, it does have the wiring already done for the car charger. I was going to install the NEMATODE 14-50R receptacle and the cover myself. I checked the circuit breaker panel and noticed that it has dual 40A breakers dedicated to the charger wiring. I believe it’s safe to install the NEMATODE receptacle. Any advise or confirmation will be highly appreciated.

Thanks

akikiki | 13 mai 2019

sherbkarki, you are going to install a worm?

tes-s | 14 mai 2019

Yes, that is the correct receptacle to install.

finished | 14 mai 2019

Here we go again. A 50 amp receptacle on a 40 amp circuit.

TeslaTap.com | 14 mai 2019

@sherbkarki - That's a bit strange, but legal, as there is no 40 amp outlet to buy, so code allows a 50 amp outlet with 40 amp breakers. Not a great approach though, because you are only allowed to draw 80% of the lower of breaker or outlet rating. It has the risk of someone plugging in something that draws continous 40 amps, which is not safe.

Turns out the Mobile connector with the M3 is limited to 32 amps, so everything will work fine so long as that's the only item used to connect to the NEMA 14-50. It might be worth adding a small sign/sticker on or near the outlet stating "32 amp max continuous current draw". Tesla makes an optional MC with a fixed NEMA 14-50 connector that can draw 40 amps. It should NOT be used in your application.

finished | 14 mai 2019

Perfectly stated, TT.

tes-s | 14 mai 2019

Actually, one adjustment to my previous comment. 14-50 is the right receptacle assuming it has a common. If only two hots and a ground, then a 6-50 is the right receptacle..

murphyS90D | 15 mai 2019

A 14-50R without all 4 terminals connected is a violation of the electrical code.