NEMA 6-50 Wiring

NEMA 6-50 Wiring

I've seen a few other posts on wiring, but still have questions.

First and foremost, I'm not sure what difference it makes having a NEMA 6-50 outlet rather than a NEMA 14-50 outlet, if any. I currently have a NEMA 6-50 outlet because it is what my GE WattStation required. I wired it with 6/2 copper wiring. From the panel to the plug is right at 40 feet. It currently has a 40 amp breaker on it.

Tesla does have a 6-50 adapter. If I buy a Tesla and want to plug into the NEMA 6-50 outlet I already have, I know I would need to buy the 6-50 adapter from Tesla, and I think I would also need to upgrade the breaker. What size breaker should be used? I'm also unsure whether or not I would need to upgrade the wiring. Is 6 gauge sufficient or should I change it out for 4 gauge? Other than buying an extra adapter, is there any downside to using a 6-50 instead of a 14-50?

Thanks for any thoughts.

Paul Koning | July 1, 2013

6 gauge is correct from what I see in the NEC, and 40 feet isn't a big distance. But that 40 amp breaker does not sound right -- you have a 50 amp outlet so I would say you need a 50 amp breaker.

I installed a 14-50 outlet (with 65 feet of 6 gauge copper in conduit) because it wasn't a big deal -- new installation either way. But Tesla doesn't need the neutral, so a 6-50 outlet works just as well.

NoMoGas | August 25, 2013

Ran my 6 gauge from the service panel and trying to bend into the box after connecting the 14-50 is taking a tone of force. Any secrets for fitting the 4 number 6 wires in a double gang metal box?


Alex K | August 26, 2013

The 40 amp breaker for the GE WattStation is correct since it's a 30A device and you don't want to draw more current than 80% of what the device can handle. As Paul mentioned before, you can increase the breaker to 50A for the Tesla adapter, since it can draw 40A. I had a similar issue with a Blink EVSE and the Blink tech was a little bit upset that I had increased the breaker to 50A to use with the Tesla adapter.

Haeze | August 29, 2013

The rule of thumb for your breaker is that it should match the amperage rating of the lowest rated part of the circuit... meaning a NEMA 6-50 outlet is rated for 50 amps. The wiring, being 6AWG, is rated for 50 amps (as long as you don't go beyond the rated length). So as long as the service, and panel you mount it in supports 50A, then a 50A breaker should be fine. Trying to put a 100A breaker on that circuit would mean the circuit is not protected. Putting a 30A breaker on it would just mean every time something tried to draw more than 30A, the breaker would trip. It doesn't introduce any fire danger, it just means a lot of headaches and outages.

Any device that is made to use less than the 50A capability of the circuit will only draw the amount of power it was designed to handle. So if the device is only 30A, and you plug it into a 50A circuit with a 50A breaker, there is no danger. The only time you have to worry about devices catching fire is if they are meant to be hard-wired, as they usually do not have any internal breaker, or power protection. In those cases, they will always require a breaker that is made for the draw of that device.

Brian H | August 29, 2013

The lowest rated may not be a good guide. If you have two of them that you may run at the same time, you'll need to accommodate that.
I suspect you need to match the HIGHEST rated.

Haeze | August 30, 2013

@BrianH going by the highest rated could be VERY dangerous.

If you install an outlet rated for 100A on a wire rated for 50A... putting a 100A breaker on the circuit will mean the wire is now your circuit breaker... and it will break the circuit by heating up and catching fire.

Your typical 15A wall outlets are still only tied to a 15A breaker, even if you have 4 of them on the same circuit. If you were to plug in two devices in separate outlets, each of which were drawing 15A, the breaker will trip (and rightfully so) because the wiring in the walls is only rated for 15A. Trying to pull 30A through those wires would be dangerous.

Even if the wiring was capable of 20A, you would not put a 20A breaker on it, because if someone plugged 20A worth of devices into one of the 15A plugs, it would cause the outlet to melt down, and the breaker would still never trip.

The breaker's job is to make sure no part of that circuit can be overloaded, so whatever your weakest link is, that is what you must tailor the breaker for.

Brian H | August 30, 2013

Obviously you can't put a breaker on circuitry designed for lower amperage. But you were going by devices, which is different. If you have a 50A wire-rated circuit and 2 devices, one drawing 25A and one 15A, on it, your formula says put a 15A breaker on it. As soon as you turn on the 25A device, the breaker flips. What's the point of that?

Haeze | August 30, 2013

When I refer to "circuit" I am talking from your Main supply, to the outlet.

Devices are not even considered when you choose which breaker to select. The breaker is based off the circuit, not off of the device. Every device will draw as much power as it is meant to draw, regardless of the rest of the circuit. An electrician's job is to install a circuit that can support the devices you will run off of it, meaning the outlets, the wiring, the main supply, and the breaker.

No one chooses their breaker by the device running off of the circuit, as the wiring would be a nightmare installing a new 0.3amp breaker, wiring, and outlet, for your new desk lamp.

Brian H | August 30, 2013

" Every device will draw as much power as it is meant to draw, regardless of the rest of the circuit. "
So I can run 10 10A devices on a 50A circuit, simultaneously? Good deal. >:p

Timo | August 30, 2013

That's correct. If you run 10 10A devices they all try to draw 10A meaning that you just blow the fuse in 50A circuit.

hpjtv | October 4, 2014

@Haeze You are for the most part correct. However there are exceptions to this rule. I'm referring to the part where you say "No one chooses their breaker by the device running off the circuit." An exception to this would be in lighting circuits as they use ballasts and are mostly an inductive load when they first start up, so you have to take imaginary current into consideration. There is a power factor that must be taken into account. That's why the utility can charge you extra if you have too much inductive loads (motors, ballasts, etc) and why companies install power factor correction.

Like you said though, I'd rather have the breaker trip than the line acting like a breaker. That's why it's usually better to use larger guage wire than needed for the breaker you have installed if you are not worried about costs.