Pre Wire For Future Car Chargers

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A/A Fuel GTX

A/A Fuel GTX

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Electrician
What is the safe way to go for pre wiring for future car chargers? I have no idea what the potential load will be so I'm thinking 6-3 nm b would cover most scenarios? Assuming car chargers require 4 wire receptacles?
 
A/A Fuel GTX said:
What is the safe way to go for pre wiring for future car chargers? I have no idea what the potential load will be so I'm thinking 6-3 nm b would cover most scenarios? Assuming car chargers require 4 wire receptacles?
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I would run the 6-3 to the outlet. The charger I just installed was a 3 wire 48 amps, or they can put a 50 amp receptacle in to charge or plug in a welder


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I see it a bit more involved especially when you state chargers.
The GC or owner needs to understand if you prepare for multiple 48 amp chargers it's not just a 6-3 circuit, it's likely a larger service (unless you follow the advice in post #3)
 
Your query is too vague for a concise answer. If your talking about a single residence, a 6/3 feed is adequate for current applications. You also need to look at your supply. is your existing service big enough to support the additional load?
 
McLintock said:
I would run the 6-3 to the outlet. The charger I just installed was a 3 wire 48 amps, or they can put a 50 amp receptacle in to charge or plug in a welder


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Car charging equipment needs to be considered continuous duty and wiring/ocpd needs to be sized at 125%. So a charger with a maximum rating of 48A is installed on a 60A circuit. 6AWG NM maxes out at 55A.

The Tesla hardwired wall connector maxes out at 48A, and supports up to 4AWG conductors, Cu only. So if you're determined to install NM, then you could install 4/2 w ground (doesn't require neutral).

Bear in mind that 2020 NEC requires GFCI protection on all charging receptacles and most hardwired scenarios.

Rob G
 
retirede said:
Keep in mind that a 48A EVSE will require a 60A circuit. 6/3 NM is only rated for 55A.
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Get a smaller EV that can be charged at 48A in under 3 hours :cool:

On an actually serious note, every time I see someone ask about sizing an EV charger I remind them that the car is going to be parked overnight.

For what it's worth, I have a 16A charger. I don't have a Tesla. If I had a Tesla I wouldn't have a 48A charger then either.
 
marmathsen said:
Car charging equipment needs to be considered continuous duty and wiring/ocpd needs to be sized at 125%. So a charger with a maximum rating of 48A is installed on a 60A circuit. 6AWG NM maxes out at 55A.

The Tesla hardwired wall connector maxes out at 48A, and supports up to 4AWG conductors, Cu only. So if you're determined to install NM, then you could install 4/2 w ground (doesn't require neutral).

Bear in mind that 2020 NEC requires GFCI protection on all charging receptacles and most hardwired scenarios.

Rob G
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So far, the 240 volt chargers I've seen on the web look like they require a 4 wire receptacle.
 
If the load is "continuous" at 48A, I don't agree.
240.4(B) would allow a 60 amp breaker but 210.19 would not allow the 60 amp load on a 55 amp conductor.
 
augie47 said:
If the load is "continuous" at 48A, I don't agree.
240.4(B) would allow a 60 amp breaker but 210.19 would not allow the 60 amp load on a 55 amp conductor.
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Point well taken but what if the charger pulses like an oven for example? I don't know if that's the case but if it is, then the continuous load factor is gone.
 
augie47 said:
If the load is "continuous" at 48A, I don't agree.
240.4(B) would allow a 60 amp breaker but 210.19 would not allow the 60 amp load on a 55 amp conductor.
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Agreed, but there's no reason to disallows a 48A continuous load on a 55A conductor on a 60A breaker. So as I have commented previously, 210.19(A)(1)(a) should be deleted, allowing the use of 240.4(B) in this situation. 210.20 and 240.4 provide sufficient rules for continuous loads.

Cheers, Wayne
 
A/A Fuel GTX said:
So far, the 240 volt chargers I've seen on the web look like they require a 4 wire receptacle.
Click to expand...

There are some that are available with either a 14-50 or a 6-50. Clipper Creek is one I’m familiar with. I think there are others.

Having said that, since this is for a future, unknown EVSE, I would plan for 4 wires.
 
retirede said:
There are some that are available with either a 14-50 or a 6-50. Clipper Creek is one I’m familiar with. I think there are others.

Having said that, since this is for a future, unknown EVSE, I would plan for 4 wires.
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I agree that the safest is to run a 4 wire circuit. Assuming conduit isn't optimal for some reason.

That said, I'm not sure how many (if any) chargers actually utilize the neutral. I've done a couple cord and plug to hardwire conversions and the neutral on the pigtail isn't even in use. Tesla has a neutral pin on their cord that comes with the car but yet the hardwired wall connector doesn't use it.
 
wwhitney said:
Agreed, but there's no reason to disallows a 48A continuous load on a 55A conductor on a 60A breaker. So as I have commented previously, 210.19(A)(1)(a) should be deleted, allowing the use of 240.4(B) in this situation. 210.20 and 240.4 provide sufficient rules for continuous loads.

Cheers, Wayne
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This intrigues me. But I fail to see where in those references it states that the conductors of a continuous load don't also need to be sized at 125% (48A x 125% = 60A min conductor ampacity)

Did you comment in another post I should go read up on to get more details?
 
210.19
(a) Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.
 
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