I am installing wiring to initially support a NEMA 14-50 outlet but later a Tesla Wall Charger. I want to oversize the wire gauge for the NEMA 14-50. If NONE of Tesla's home chargers use the neutral leg, I will save money and time by not including the neutral wire. Am I understanding this correctly?
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JasJ
Member
True, but if you're running a 14-50 first, run a thinner/cheaper (but appropriate for 50A) gauge neutral so you are not violating code by installing an outlet without a neutral, could be quite dangerous for non-Tesla use.
Yes, BUT a 14-50 still needs the neutral wire to be installed to code since a 14-50 itself needs the neutral wire. See Flasher's FAQ in my sig for more.
Anything that is STRICTLY 240 VAC does not need it, since you are using only the two legs of the 240 supply. Anything that could theoretically peel off one of the legs and supply 120VAC to something (using the neutral) has to have a neutral, and that's why the 14-50 requires a neutral.
SO, a 14-50 needs a neutral, BUT wires run strictly for an HPWC do not. Since there is no 120 use there and can't be one.
Anything that is STRICTLY 240 VAC does not need it, since you are using only the two legs of the 240 supply. Anything that could theoretically peel off one of the legs and supply 120VAC to something (using the neutral) has to have a neutral, and that's why the 14-50 requires a neutral.
SO, a 14-50 needs a neutral, BUT wires run strictly for an HPWC do not. Since there is no 120 use there and can't be one.
Correct. For a the HPWC, some installers in my area use Romex 6/2 (has black, white and ground) and they just mark the white wire with red tape or paint on each end to designate it as a power phase and not neutral. Or they use 6/3 (has black, white, red, and ground) and not use the white wire. I think it just depends on what they have in the truck when they show up for the job. Both of those wires are rated at 55 amps.
I would think that for the NEMA 14-50 on a 50 amp breaker, they would need to install all 3 conductor wires and the ground to meet code. It's not that much more expensive for 6/3 compared to 6/2 (looking at Lowe's website). The labor is what costs the most. To install a NEMA 14-50 near the breaker box here costs around $250, last I checked.
I would think that for the NEMA 14-50 on a 50 amp breaker, they would need to install all 3 conductor wires and the ground to meet code. It's not that much more expensive for 6/3 compared to 6/2 (looking at Lowe's website). The labor is what costs the most. To install a NEMA 14-50 near the breaker box here costs around $250, last I checked.
If you don't want to run a neutral wire, a NEMA 6-50 receptacle is the correct one to use. It does not have a neutral pin, but it is still a 50A receptacle, so your car will charge at the same rate. Tesla sells a UMC adapter for it.
Derek Kessler
Active Member
You are correct that a 14-50 plug does have a neutral line and that Tesla chargers do not use it. But if you are installing an outlet you ABSOLUTELY MUST install it with the correct wiring. Just because you don't need it now for your car doesn't mean somebody else won't later down the line.
This level of electrical install is easy, but the kind of power we're talking about is not to be toyed with. Do it right or don't do it at all.
This level of electrical install is easy, but the kind of power we're talking about is not to be toyed with. Do it right or don't do it at all.
It's pretty common for folks with single air conditioner campers to use an adapter to plug into a NEMA 14-50 to run the camper. This requires the ground to get 110V. If it is not there, well, I don't want to see the results.
Just do it right. You spent $100k+ for the car, don't skimp on $50.
PWlakewood
Active Member
So just cap the white wire off then? I just purchased the Tesla home charger and I already have a 14-50 outlet that is wired to code which uses the white wire and I will be adding a 14-50 plug instead of hardwiring the charger.
PWlakewood
Active Member
Yes the outlet I had installed will stay that way if/when we sell one day. My question was do I just cap off the white wire that in comes with the cord that I will be using?
Zamp
Member
Yes, I have added 14-50P "pigtails" to several HPWCs. On the end that connects to the HPWC, just cap off the white.
The netural is for AC power and ground is for DC power. The issue is if someone uses the 220v for a 120 with a splitter etc and runs a AC item without a netural wire the power has nowhere else to go. The netrual is a return of power and is constant. So if you plug in that AC item and it gets a surge of power etc it will cause an imbalance of power and can cause equipment issues and personal harm because the power has no way to return. If you run a DC item the ground is a fail safe to take power if it has no where to go either from over powered or say you some how make contact to the live wire if there is no ground then you become the ground. I would recommend connecting the correct Nema the right way. Or use a different that doesn't have 4 wires. This way you won't be able to buy pig tails that would make incorrect splits to 120v etc.
Concerned
Member
The NEC (national Electrical Code) and IEEE red Book define the neutral as a current carrying conductor and the ground or earth as a safety current path for stray electrical currents. One has potential (voltage) the other is intentionally zero under normal circumstances. (even if they are bonded at the same point electrically at the service entrance point) The wall connector and gen 2 connector determine if there is an effective ground path through some deminimis leakage current (not enough to trip a ground fault circuit breaker) It appears that Tesla does not utilize the neutral yet other responses are correct, per code if you install the 4 wire device, you need to run all four wires and it’s plausible that some future use could require it. If you choose to use the gen 2 adapter that accommodates various plug configurations, its max current is 32 amperes and can be effectively sourced with number 8 awg and a 40 ampere circuit breaker provided the device is rated for 75 degree c terminations and the cable insulation itself is listed for 75 degree c on table 310-16. A licensed electrician will understand these matters and will install the 6-50 receptacle (3 wire) or the 14-50 (4 wire) receptacle at your direction. Depending on the distance, costs might not be immaterial. If you are purchasing the gen 2 connector with the integral 14-50 plug, its rating is 40 ampere continuous supply and must be served by #6 awg and a 50 ampere circuit breaker. The NEC requires power circuits and devices to be derated to 80% of capacity for a continuous load, (which is also defined as a load that is 4 hours or greater) and the charge cycle of our Teslas easily meet that definition. If you don’t really know what you are doing hire a qualified individual. I am served by a utility that has a 6 hour super off peak rate and it’s desirable to do my daily charging in that time period. One other thing many ignore is that the overall service (to the home) needs to be considered if you push the current in amperes to max. Although my MY is limited to 11 kw which nominally is 45 amperes continuous or a 60 ampere circuit, sourcing a wall connector. Which while likely be future proof, the overall load, ac, range, dryer, lighting and nominally assigning 180 watts per receptacle in the home needs to be considered. Homes may have anything from 60 ampere service to 400 or more yet most commonly 100, 150 or 200 which also has to be derated by 80%. Tesla has the means to power limit multiple wall connectors, yet if you happen to soon also have a Lightning, as I hope to soon, I’m going to have to schedule charging such that my 200 ampere service isn’t overloaded, and will integrate that with my air conditioning controls, upgrading the service that underground to my home is impractical. I might use two wall connectors integrated and an adapter for ccs for the lightning, so the demand limit is automatic. (Ford claims their max is apparently maxed at 90 amperes, which I can‘t practically do) BTW, I’m a power engineer
strider
Active Member
Teslas do not use the neutral. But I agree with @markb1 if you want to save on copper and labor for larger wire, install a 6-50. That only needs 3 wires. Then there is no question about what is inside the box and no one can screw up and plug in something that needs the neutral. A Leviton receptacle is $14 at Home Depot.
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