14-50 on 100 amp breaker? Ok to use?

[Blacktes24]

I have a setup here on the farm with all sorts of electrical connections with varying plugs/breakers with 240 service and I have one 14-50 outlet that was used for a big electric motor that is no longer used so I plugged my 14-50 with the mobile connector into it and it seems to work great and I am getting 29 mph charge rate. It shows 32 amps and 246/247 volts. I researched what I could and seems like it shouldn't be an issue as it's not like I'm putting more power to the car with a 100 amp versus 50 amp breaker it just will give the connector what it needs with ease.


Also is it ok for the Gen 2 mobile connector to be used/left out in the rain? Not a permanent solution but something to use for now until I get my permanent solution done. Thanks!

 

[Gauss Guzzler]

Yeah it'll work just fine but you're missing much of the fire protection that the circuit breaker is intended to provide. Your outlet and its wiring (presumably) are rated for 50A peak / 40A continuous but it's not uncommon to install a much larger breaker to withstand the surge of a welder or large machinery. This is an unsafe workaround but legal, in part because there's no alternative, but also the assumption that the person welding would likely notice the power loss and ensuing fire.

Car charging is different in that it will pull 32A non-stop for 5-10 hours, unattended, overnight, and absolutely has a tendency to overheat faulty wiring that might not have any trouble with other high power machinery. You'd be wise to swap in a 50A breaker, and even wiser to make it a GFCI breaker as required by code.

The mobile connector seems to do OK outdoors but it is not intended/rated/designed for outdoor use. Tesla's Wall Connector is a much better solution.

 

[sightman]

I would add a smaller breaker, 60 amp. At 100 you have too much room to cook the wires in the event of a fault and potentially start a fire in your wall where the cable is running.

 

[rpiotro]

I never saw any mention of the wiring. Is it appropriate for 100 amps? If not, put in the correct breaker or you are asking for trouble. If the wiring can handle 100 amps then there is no problem with using a device with a lesser draw.

It is like asking "Can I plug in a device that uses 3 amps into my household 15 amp circuit?" Well duh. The converse would be "Could I plug in a device that requires 50 amps into my household 15 amp circuit if I upgrade my circuit breaker?" Well duh again.

 

[T4M3]

NO!!! Use a 50 amp breaker!

 

[Blacktes24]

I never saw any mention of the wiring. Is it appropriate for 100 amps? If not, put in the correct breaker or you are asking for trouble. If the wiring can handle 100 amps then there is no problem with using a device with a lesser draw.

It is like asking "Can I plug in a device that uses 3 amps into my household 15 amp circuit?" Well duh. The converse would be "Could I plug in a device that requires 50 amps into my household 15 amp circuit if I upgrade my circuit breaker?" Well duh again.

Yes it is appropriate for for 100 amps. The whole setup is for grain bins with big electric motors. i'm not worried about the wiring as I know it is fine. I was just worried about possible damage to the connector or car.

 

[Blacktes24]

I would add a smaller breaker, 60 amp. At 100 you have too much room to cook the wires in the event of a fault and potentially start a fire in your wall where the cable is running.

I will swap it out after reading this thread but it can't cause a fire as the breaker box is outdoors mounted to the side of a metal grain bin. I just don't want it to hurt my car.

 

[E90alex]

It won’t hurt the car, the car will only pull what it can which is 32A with the mobile connector. Having a 100A breaker doesn’t mean the panel is going to push 100A to the car.

 

[Lloyd]

Yes it is appropriate for for 100 amps. The whole setup is for grain bins with big electric motors. i'm not worried about the wiring as I know it is fine. I was just worried about possible damage to the connector or car.

The motors need to be on a different circuit from the plug. If not rewire as appropriate. Change the breaker and verify that the wire size is #6 copper or better. Sounds like you need a consultation with an electrician and this blog is not going to be sufficient to get your answers.

 

[Jeremy3292]

Waiting for @Rocky_H to chime in but this is not "smart". If there is a surge in power the breaker won't trip and you could start a fire, or something along those lines. That's why properly sized breakers are important.

You can do whatever you want but if you are asking what is the safe thing to do the answer is replace the breaker with an appropriate sized one.

 

[Blacktes24]

It won’t hurt the car, the car will only pull what it can which is 32A with the mobile connector. Having a 100A breaker doesn’t mean the panel is going to push 100A to the car.

This is all I was looking for. I didn't think it would do anything to it just wanted to be sure the mobile connector would just pull what it was suppose to. Thanks!

 

[Gauss Guzzler]

Yes it is appropriate for for 100 amps. The whole setup is for grain bins with big electric motors. i'm not worried about the wiring as I know it is fine.

Your wiring isn't appropriate, you'd need AWG 2 or AWG 3 for a 100A circuit and that wouldn't fit in a 14-50 receptacle. So surely some/all of the wiring is AWG 4 or AWG 6.

 

[57nevets]

I have a setup here on the farm with all sorts of electrical connections with varying plugs/breakers with 240 service and I have one 14-50 outlet that was used for a big electric motor that is no longer used so I plugged my 14-50 with the mobile connector into it and it seems to work great and I am getting 29 mph charge rate. It shows 32 amps and 246/247 volts. I researched what I could and seems like it shouldn't be an issue as it's not like I'm putting more power to the car with a 100 amp versus 50 amp breaker it just will give the connector what it needs with ease.


Also is it ok for the Gen 2 mobile connector to be used/left out in the rain? Not a permanent solution but something to use for now until I get my permanent solution done. Thanks!

I added a 14-50 outlet to the 100 amp panel of my house. The outlet does have its own breaker. I am using a mobile connector. It would be wise to protect the connector from rain since it has holes on its side. A plastic bag over the connector would help. I have a permanent box over the 14-50 outlet and connector.

See this thread: Intermittent Charging with Mobile Connector Fixed

 

[Outpost53]

If a motor is no longer used on the circuit I would replace the breaker with the correct one for the wire size. The breaker was likely the correct size for the motor since you are allowed (and required) to upsize breakers for motors so they don't trip when they have a huge inrush current on startup for a split second and motors have built in protection to protect the wiring. It should have been hardwired however. Now that you are using that port to charge it is a complete different load and you should size the breaker for the wire size.

 

[Outpost53]

If a motor is no longer used on the circuit I would replace the breaker with the correct one for the wire size. The breaker was likely the correct size for the motor since you are allowed (and required) to upsize breakers for motors so they don't trip when they have a huge inrush current on startup for a split second and motors have built in protection to protect the wiring. It should have been hardwired however. Now that you are using that port to charge it is a complete different load and you should size the breaker correctly.

 

[UncleCreepy]

Regardless of whether the wires can handle 100 Amps, a NEMA 14-50 outlet is rated for 50 Amps, not for 100 Amps. The safe thing to do is to replace the breaker with a 50 Amp model.

 

[Gulfcoaster]

Guys, what is the correct code compliant size wire to use with a 50 amp breaker using the NEMA 14-50 plug or Tesla Wall Charger?

The run length in my situation from panel to plug or charger location is short, about 10' to 12'

Thanks

 

[roblab]

A 50-amp breaker costs less than $20 at The Home Depot. It's cheap home insurance. Pull the 100 amp for use in another place and put in the proper size. That's what breakers are for.

Imagine putting in a 100-amp breaker in your household outlet circuit. Your toaster could burst into flames. You're missing the point.

 

[stopcrazypp]

Guys, what is the correct code compliant size wire to use with a 50 amp breaker using the NEMA 14-50 plug or Tesla Wall Charger?

The run length in my situation from panel to plug or charger location is short, about 10' to 12'

Thanks

Tesla recommends 6 AWG for 14-50:
https://www.tesla.com/sites/default/files/downloads/en_CA/CA-EN NEMA 14-50 Installation Guide.pdf
6/3 wire typically comes with a smaller ground wire of 10AWG or 8 AWG, which is allowed.

Note that starting with 2017 NEC a GFCI breaker is required if using a 14-50 based EVSE. If hard wired, it is not required. Check your local code to see what version they are on. Pro-tip: if you have a hard time finding stock of GFCI 50A breakers that are UL listed for your panel or sellers are charging ridiculous prices for them, sometimes you can find SPA panels at electrician supply stores with them for less expensive than the breaker alone. That's what I had to do for mine. Either way it'll cost you around $100 for the breaker.
According to here Florida should be on NEC 2017 already:
https://www.iaei.org/page/florida-electrical-ceus

Another thing of note is with the Gen 3 wall connector, some inspectors may require you to install a 60A breaker and associated wiring as they may not recognize the software toggle as a legitimate way of limiting demand (the older models had dip switches). Found an example here, in Canada:
Is it safe to use 70 amp breakers for home wall connectors to charge Model 3?
You may want to ask your building inspection department if they have any associated rules in this regard before spending money on wires and breakers (or you may have to rip them out again).

 

[UncleCreepy]

Imagine putting in a 100-amp breaker in your household outlet circuit. Your toaster could burst into flames. You're missing the point.

It can still burst into flames, even on a 15 Amp circuit. The breaker's job is to protect the wiring between itself and the outlet, nothing else.
With that said, the correct size breaker should still be used though.