Installing a Nema 14-50 on a 30 Amp Breaker

[Whoster69]

I have a 240-volt dryer circuit on a 30 amp breaker that I'm not using (I have a gas dryer) I was thinking putting in a Nema 15-40 on this 30 amp breaker to charge a model 3 long range. Here are my questions:

1) Will this work?

2) About how many miles of charge can I get off of this setup with a 30 amp breaker?

Thanks for the help.

 

[M3BlueGeorgia]

No NO no

On a 240v-30A breaker, please, please use the correct 14-30 socket and spend $35 with Tesla to get the correct adapter.

With 14-30, you'll get around 22mph.

Note: This is the setup I have.

 

[Whoster69]

22 mph would be fine. What is wrong with 15-40? I'm new at all of this and I'm trying to understand.

Thanks for the help!

 

[Alketi]

And, you meant NEMA 14-50, not 15-40.

And the answer is still no.

(The reason is -- you cannot put a higher current outlet on a lower current breaker with lower current wiring, and then "try" to use it carefully. It's both illegal and obviously dangerous, unless you don't mind burning your house down.)

 

[Whoster69]

And, you meant NEMA 14-50, not 15-40.

And the answer is still no.

Thanks. I keep getting those backwards.

 

[eprosenx]

Note that dryer receptacles are typically 14-30 or 10-30. The older ones being 10-30. Tesla sells adapters for both.

New 10-30 receptacles are not allowed since they don’t have any ground wire (hot hot and neutral only).

Lots of folks charge just fine off dryer receptacles. They will provide 24a of charging where as a 14-50 will do 32a if using a UMC Gen 2 (what comes with the cars now).

 

[DriveMe]

What is wrong with 15-40?

You can’t put NEMA 14-50 receptacles on a 30A circuits! Not only that would be a code violation, but it would cause immediate problems when charging a Tesla! Here is why.
The type of the NEMA plug (adapter) you use with the UMC tells your car what’s the highest current the car is allowed to draw. If you use the 14-50 adapter, the car will assume you have a 50A rated circuit and will charge at a higher current than it’s supposed to! At best this will trip your circuit breaker, at worst, this can cause fire!

DO NOT DO IT!!!

 

[ry-ballz]

22 mph would be fine. What is wrong with 15-40? I'm new at all of this and I'm trying to understand.

Thanks for the help!

The outlet will have the ability to draw more current than the breaker (and likely the wiring can support.)
In addition to being illegal, it could start a fire if the breaker was to fail, and old breakers fail a lot.
Not just a small fire at the outlet, like the entire wire inside your walls just instantly started to melt and now you have an in-wall fire from your breaker box to the outlet.

 

[brkaus]

Buy the correct adapter and be safe!

You will get good charge speed and meet your needs unless you drive 100s of miles a day.

 

[Petrlol]

Buy the right adapter here.
Gen 2 NEMA Adapters

Perfectly safe this way.

 

[Whoster69]

Thanks for the advice and explanations everyone. I will take this into account before doing anything.

 

[timk225]

What's a 15-40?

OP, read this, get familiar with the outlets.

NEMA connector - Wikipedia

At least read the 5,6,10, and 14 sections, those are what Teslas can use. And are 99% of the outlets in the average home.

 

[Castlerock]

In case you have charge rate envy, you WILL be happy with the 30A service. Seriously. The LR will fully charge (10-90) overnight with that rate. Key assumption in this, is that you don't have to run a new circuit to get where you want to charge. If you can just reroute what you have, you will save $$

 

[WhatIsThis]

Its also worth remember that the Gen 2 mobile charger can only push 32amps. So if you do have a 50amp circuit it won't be able to take advantage of it.

 

[DiegoFro]

This will not work. The 14-50 adapter from Tesla that plugs into the Gen 2 mobile connector will try to draw more than 30 amps and it will trip your breaker. You would need to set the car to draw 22 amps, but I do not know if it will remember every time you plug in. It will most likely try to draw 32 amps first. I have a 10-30 at home and I get 22 miles of charge back in an hour.

 

[jsshapiro]

The breaker and the wiring are both rated for a certain amperage. If too too much current is drawn through the circuit, the wire overheats and will likely start a fire. The breaker is there to try to protect your house from this.

I agree that 30A is fine for recharging a single Tesla. We’re just putting in a second charger, and I expect 30A will do fine for both of our cars most nights. If not, we’ll rewire with a higher capacity circuit.

 

[Mbrockus]

I read a post a while back where someone made a 20 ft cable with a 14-30 plug and 14-50 receptacle and kept it in their Model S for charging from a dryer outlet. For the new mobile chargers would that lead to a current overdraw?

 

[Petrlol]

I read a post a while back where someone made a 20 ft cable with a 14-30 plug and 14-50 receptacle and kept it in their Model S for charging from a dryer outlet. For the new mobile chargers would that lead to a current overdraw?

Yes. The 14-50 on the end of the UMC makes it think it can pull 32 amps. On a dryer outlet that is 30amp you should only pull 24 amps. So pulling 32 amps on a 24amp (constant) circuit will trip the breaker... or much worse.....

They should have gotten the 14-30 adapter, and not use an extension cord.

There are ways to limit the charging on the screen and do it with extension cords and such, but nothing I would post or recommend online as people are well... people....

 

[StellarRat]

I think the breaker will trip every time you try to charge. Why don't you just get the right wire for 50 amps and upgrade the breaker to the proper 50 amps?

 

[RaeW]

I have a 240-volt dryer circuit on a 30 amp breaker that I'm not using (I have a gas dryer) I was thinking putting in a Nema 15-40 on this 30 amp breaker to charge a model 3 long range. Here are my questions:

1) Will this work? Maybe

2) About how many miles of charge can I get off of this setup with a 30 amp breaker?
I generally get 18-19 MPH.

Thanks for the help.

I did this exact same thing, but there are cautions.

My electric dryer outlet, while dedicated, is fed from the panel to a junction box in the basement rafters. This is because the genius electrician who did original construction knew I had a gas dryer and tried to save a few bucks by running a line in the basement only (dryer is above box on first floor). I made him complete the job before we moved in. Several years ago I disconnected the dryer outlet at the junction box and ran the line to the garage (luckily the electrician had used a deep junction box). I have been using this 30 amp circuit for charging my MS (at 24 amps) since 2015.

NOTE THE REQUIREMENTS:
Check your local building code.
You must use the proper gauge wire for the distance (your dryer line may or may not meet this requirement).
You must use the proper outlet (don't use the dryer outlet).
You can only charge at 80% of breaker rating (24 amps on a 30 amp breaker).