Best plug type for EV charger?

[STS-134]

Just like I have too much solar and batteries, I want to put in the best of the best for my garage EV options. Only get to pay for wiring once.

100A wiring that can do 80A of continuous load, just in case you get a Lucid or Rivian with an 80A OBC? Might not fit into the connectors for a 14-50 outlet though, so you might have to feed the larger wires into a device that can also attach to smaller wires before attaching to your 14-50 outlet.

 

[ATPMSD]

I only see some 14-50 ev plug charges but I assume this is just because if was already wired?

If you look at the options for most of them you can choose a 14-50 or a 6-50 connection, they show the 14-50 because it is most common. With either the 14-50 or 6-50 you are limited to a 50 amp circuit while a hardwire version takes you to 60 amps. Most, but not all offer hardwire versions.

 

[OliverM3]

A lot of good info here. I was really surprised how many electricians really don't have a good handle on ev charging. Still trying to fix my setup which is on Romex. My charger also doesn't fit larger than #6 so running something larger isn't an option. It needs to be #6 thhn

 

[h2ofun]

As long as the 14-50 outlet you're using can take the larger wiring, and you downsize the breaker to 50A for now, it should work. There shouldn't be an issue just keeping the breaker off and the wires capped off until you get your new EVSEs.

I believe I have a NEMA 14-50 on 4/3 romex with a 50A breaker. This can easily be upgraded to a 60A circuit if needed in the future. The WC on the other side of the garage is also connected to 4/3 romex and is on a 60A circuit, for the full 48A worth of continuous load. Plugged into the NEMA 14-50 is a Chargepoint Home (the old 32A edition) that I use for my PHEV, which only has a 16A OBC in it. If that Chargepoint Home were to die and I got a Chargepoint Home Flex, I could actually hardwire that unit, and it will do up to 50A (which would require upsizing the breaker to 70A). I'd probably just plug it into the 14-50 and configure it to do 40A max for now but if I changed vehicles in the future and the future vehicle had a 48A or 50A OBC, I'd be able to easily up the current by just switching the breaker. In my case, the panel is in the garage and so the wires are easily accessible; your situation may be different.

WOW, 4/3 romex is EXPENSIVE. Home depot, 500 feet, 5600 bucks.. 6/3 romex is like 2200 for 500 feet. But using 4/3 I assume means you can basically do whatever you want. But then I read big different if 60C vs 90C speced?

 

[STS-134]

WOW, 4/3 romex is EXPENSIVE. Home depot, 500 feet, 5600 bucks.. 6/3 romex is like 2200 for 500 feet. But using 4/3 I assume means you can basically do whatever you want. But then I read big different if 60C vs 90C speced?

Sounds about right. My electrician gave me the invoice from his supplier. It was close to $500 for 50 feet of the stuff.

 

[Midnightsun]

Still cannot figure out why all our houses are not burning down in Canada. I used Romex 6/2 for both my wall connectors, rated at 75amps. Have searched and cannot find the physical difference between NMD90 Canadian spec and NM-B90 US spec. 6 gauge copper is 6 gauge copper and will easily support over 60 amps however there must be something with the insulation that sets them apart. Regardless, not acceptable to use this in the US.

If you live in Canada, yes Romex 6 gauge is more than adequate as it is rated at 75A. NMD90 6/2 Cu G Rd 492R | Southwire

 

[ATPMSD]

WOW, 4/3 romex is EXPENSIVE

Price out with thhn wire. Yes you need conduit but that is not expensive.

 

[OliverM3]

Still cannot figure out why all our houses are not burning down in Canada. I used Romex 6/2 for both my wall connectors, rated at 75amps. Have searched and cannot find the physical difference between NMD90 Canadian spec and NM-B90 US spec. 6 gauge copper is 6 gauge copper and will easily support over 60 amps however there must be something with the insulation that sets them apart. Regardless, not acceptable to use this in the US.

If you live in Canada, yes Romex 6 gauge is more than adequate as it is rated at 75A. NMD90 6/2 Cu G Rd 492R | Southwire

I agree it is a little strange since the wire is 90c in Romex but they hold to the 60c standard. Possibly because older Romex is only 60c? So they just downrate the newer stuff? Or at least that's what I see from reading.

 

[OliverM3]

WOW, 4/3 romex is EXPENSIVE. Home depot, 500 feet, 5600 bucks.. 6/3 romex is like 2200 for 500 feet. But using 4/3 I assume means you can basically do whatever you want. But then I read big different if 60C vs 90C speced?

If you go that route make sure the charger you want will accept it. The lugs on mine will only support #6

 

[STS-134]

If you go that route make sure the charger you want will accept it. The lugs on mine will only support #6

Can't you get a device that has lugs that take both #4 and #6 and connect everything up? Easier to pull that device off the wall than to open up the walls and rewire everything.

 

[OliverM3]

Can't you get a device that has lugs that take both #4 and #6 and connect everything up? Easier to pull that device off the wall than to open up the walls and rewire everything.

Yeah I'm sure you can do a junction that takes it down from 4 to 6. I'm at 2hours for my 100 miles per day at 48 amps so really how much are you driving to invest the money? even 32 would be fine for my unusually long commute so I guess it depends what he needs. Why spend money on having a 100amp charger if you drive less than 100 miles per day? Maybe with some sort of taxi service higher amps would be great but 32, 40, 48 really is fine for anything I would drive.

 

[wwhitney]

#6 Romex is only rated at 55amps so a 50 amp breaker but #6 thhn is good for 75amps.

#6 THHN is only good for 65A in the simplest sense of "good for".

Both #6 NM and #6 THHN have a 75A base ampacity for when you need to derate for high ambient temperature (above 30C) or for more than 3 current carrying conductors in a cable or conduit.

However, #6 NM is limited to 55A as a final ampacity because of an NM-specific rule in the NEC. #6 THHN is limited to 65A as a final ampacity because of the terminations limits of equipment. [It would be possible, although extremely rare, to use #6 THHN at 75A if the wire doesn't terminate on equipment at either end, but is spliced to other larger conductors.]

For the OP, I absolutely suggest omitting a neutral for any EVSE circuits. The use of NEMA 14 receptacles for EVSE, while common, is stupid in my view. And wire is expensive these days.

I'd suggest using SEU cable, which is not subject to the extra limitation that NM cable is. Either 6-6-6 Cu SEU (somewhat hard to find) or 4-4-4 Al SEU. You'll end up with an oversized EGC, but I think it's the most cost effective cable option (aluminum typically being cheaper than the equivalent size (2 smaller) of copper).

Cheers, Wayne

 

[OliverM3]

#6 THHN is only good for 65A in the simplest sense of "good for".

Both #6 NM and #6 THHN have a 75A base ampacity for when you need to derate for high ambient temperature (above 30C) or for more than 3 current carrying conductors in a cable or conduit.

However, #6 NM is limited to 55A as a final ampacity because of an NM-specific rule in the NEC. #6 THHN is limited to 65A as a final ampacity because of the terminations limits of equipment. [It would be possible, although extremely rare, to use #6 THHN at 75A if the wire doesn't terminate on equipment at either end, but is spliced to other larger conductors.]

For the OP, I absolutely suggest omitting a neutral for any EVSE circuits. The use of NEMA 14 receptacles for EVSE, while common, is stupid in my view. And wire is expensive these days.

I'd suggest using SEU cable, which is not subject to the extra limitation that NM cable is. Either 6-6-6 Cu SEU (somewhat hard to find) or 4-4-4 Al SEU. You'll end up with an oversized EGC, but I think it's the most cost effective cable option (aluminum typically being cheaper than the equivalent size (2 smaller) of copper).

Cheers, Wayne

I agree I see everyone saying 14-50 but I don't understand why none of the chargers need the extra wire.
Also I was looking at the #6 THHN MC which shows 75amps https://www.amazon.com/Wirenco-Aluminum-Armored-Stranded-Conductor/dp/B09317LDBB?th=1

 

[wwhitney]

Also I was looking at the #6 THHN MC which shows 75amps https://www.amazon.com/Wirenco-Aluminum-Armored-Stranded-Conductor/dp/B09317LDBB?th=1

That URL correctly says "75A at 90C". None of the equipment you would hook up each end to (like a breaker and the EVSE) is rated for 90C terminations, they are limited to 75C. So you only get to use it at 65A.

Cheers, Wayne

 

[OliverM3]

That URL correctly says "75A at 90C". None of the equipment you would hook up each end to (like a breaker and the EVSE) is rated for 90C terminations, they are limited to 75C. So you only get to use it at 65A.

Cheers, Wayne

Yeah just saying it's good for #6 on a 60 amp breaker. Unlike Romex.

 

[Ampster]

If you were to only have wiring that can support a NEMA 14-50, you won't be able to take full advantage of your new EVSEs.

On the other hand, how many EVs have onboard chargers that go higher than 32 Amps?

 

[Vines]

#6 THHN is only good for 65A in the simplest sense of "good for".

Both #6 NM and #6 THHN have a 75A base ampacity for when you need to derate for high ambient temperature (above 30C) or for more than 3 current carrying conductors in a cable or conduit.

However, #6 NM is limited to 55A as a final ampacity because of an NM-specific rule in the NEC. #6 THHN is limited to 65A as a final ampacity because of the terminations limits of equipment. [It would be possible, although extremely rare, to use #6 THHN at 75A if the wire doesn't terminate on equipment at either end, but is spliced to other larger conductors.]

For the OP, I absolutely suggest omitting a neutral for any EVSE circuits. The use of NEMA 14 receptacles for EVSE, while common, is stupid in my view. And wire is expensive these days.

I'd suggest using SEU cable, which is not subject to the extra limitation that NM cable is. Either 6-6-6 Cu SEU (somewhat hard to find) or 4-4-4 Al SEU. You'll end up with an oversized EGC, but I think it's the most cost effective cable option (aluminum typically being cheaper than the equivalent size (2 smaller) of copper).

Cheers, Wayne

I would agree with everything except to use the of aluminum wire. The Tesla HPWC for instance specifically calls out copper only.

Maybe some #6 MC? #6 MC 250' Spool for $1,125 for 250'? I don't work with MC much, but this is an option.

Also, do you really want all chargers to pull full ampacity? If you don't mind sharing a bit, why not just run (3) 60A Wires and each one can have a pair of Gen 3 HPWC on them sharing the circuit. I use a relatively cheap $160 adapter to charge J1772 cars at 48A on my two Tesla HPWC. I do not share a circuit on mine since they are on opposite sides of the house.

This way the first 3 cars could charge at 48A each, then additional cars charging would share that 48A rate.

This may reduce the load on @h2ofun transformer, which the utility and possibly neighbors would appreciate if it is a shared unit.

 

[wwhitney]

I would agree with everything except to use the of aluminum wire. The Tesla HPWC for instance specifically calls out copper only.

Right, I forgot many EVSEs specify copper only when hardwiring. That could be sidestepped by installing a (not required) disconnect for the EVSE and transitioning to copper. Not worth it for short runs, just use copper only, but for long runs could be worth it.

Cheers, Wayne

 

[jgleigh]

I agree I see everyone saying 14-50 but I don't understand why none of the chargers need the extra wire.
Also I was looking at the #6 THHN MC which shows 75amps https://www.amazon.com/Wirenco-Aluminum-Armored-Stranded-Conductor/dp/B09317LDBB?th=1

All of the chargers are only using 240V which doesn't need the neutral wire. The neutral wire is only needed for 120V or older homes that used it as ground (NEMA 10-30 or 10-50).

 

[STS-134]

On the other hand, how many EVs have onboard chargers that go higher than 32 Amps?

Off the top of my head, I can think of:
1. All Teslas except the M3 SR+
2. Rivian EVs
3. Lucid EVs

In the future? Who knows. Better to just future proof your setup so that upgrading is easy. I suspect that most larger vehicles (anything using more than 300-400 Wh/mi) will be getting a > 32A OBC.