EV Chargers: How to Choose the Right One for Your Home

[ajdelange]

There is no plug/receptacle rated at 60A,

in no small part because code requires anything over 50A to be hardwired.

Huh?

You can absolutely install wiring capable of handling 60A, but if you want a plug in EVSE will need to put it on a 50A (or smaller) breaker with the appropriate receptacle.

14-60R receptacles are fairly rare and plug in chargers for them even rarer but they are available:

I guess you could install a 14-50R and mount one of those in such a way that you could quickly dismount it, unplug it and take it inside when not using but I think that would be pretty clumsy. If unplugging for security is desired Id say go with the 14-50R option and a portable charger. You are only losing 16.6%.

Most will be able to fully recharge from a typical days driving in a couple of hours on a 40A circuit.

While you can legally install a 14-50R on a 40 A circuit I wouldn't do that. You would then have to charge at 32 A and with the high utilization of these vehicles you really want to get as much as you can. If you decide on the receptacle route then pull No. 6 and put it on a 50 A breaker.

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[ajdelange]

There is no plug/receptacle rated at 60A, in no small part because code requires anything over 50A to be hardwired.

It just occurred to me that perhaps you are referring to some municipal, state or county code which may indeed be the case but there are no such restrictions in the NEC (National Electrical Code). What we can take from this is that local codes need to be checked too.

 

[skyote]

There is no plug/receptacle rated at 60A, in no small part because code requires anything over 50A to be hardwired.

https://www.homedepot.com/p/Leviton...rounding-Outlet-Blade-061-09460-000/301344350

You can also install a 50A outlet on a 60A circuit, and 60A is the right size to use if actual draw was @ 48A anyway.

 

[ajdelange]

You can also install a 50A outlet on a 60A circuit, and 60A is the right size to use if actual draw was @ 48A anyway.

Are you sure about that? It's in my head that the only exceptions to the rule that the receptacle must match the circuit was the the 14-50 (and, of course, the 5 - 15)

 

[skyote]

Are you sure about that? It's in my head that the only exceptions to the rule that the receptacle must match the circuit was the the 14-50 (and, of course, the 5 - 15)

I should have used a disclaimer. ;-) I am not an electrician and cannot speak to local code requirements. Best to talk to a certified local electrician.

But it will work. Not sure if there is a legit risk if you pulled more than 50A on an outlet not specifically rated for higher, but as with most things, probably better safe than sorry.

 

[skyote]

OK, now I've thought about it a little more & feel like I should provide better advice...

To keep things simple & safe, install a 50A circuit with a NEMA 14-50 outlet. Many EVSEs have an option for a NEMA 14-50 plug, so you'll be in great shape and have plenty of EVSE options at your disposal.

 

[ajdelange]

But it will work. Not sure if there is a legit risk if you pulled more than 50A on an outlet not specifically rated for higher, but as with most things, probably better safe than sorry.

The code has evolved over many years (80 - 100 ?) and there are often things in it that don't make sense such as a restriction against putting a receptacle rated for 50 A on a 60 A circuit. What's the problem there? You will never plug a load bigger than the circuit can handle into a 50 A outlet if the circuit is rated at 60 A. So we can only guess why that prohibition is there (if indeed it is there i.e. if I remember correctly). Lets say you plug a piece of 50 A equipment into a 50 A outlet on a 60 A circuit and the equipment fails and starts to draw 65 A. There is clearly a problem with the equipment but the 60 A breaker won't trip for quite a long time because it is designed to handle 65 A for quite a few minutes. Were you on a 50 A breaker it would trip much quicker. What you can do is pull No. 6 and put a 50 A breaker on it and then install a 14-50R. That suggests there may be something to my thesis.

What I can say with more certainty is that somewhere along the line putting a 50 A receptacle on a 60 A circuit caused a problem. The mechanism by which the code grows is that someone observes a problem, fills out the card in the back of the book and sends it off to the NFPA who reviews it and modifies the code as necessary to remove the risk if the committee determines that there is indeed a risk. It is clear that in many cases the actual risk presented requires a "perfect storm" to materialize but keep in mind that the NFPA is essentially insurance guys trying to minimize the number of claims they will have to pay out be those claims the result of a perfect storm or not.

I think it always a good idea to consult a competent local electrician defined as one who has worked with the inspector who will be approving your installation. These guys are wrong sometimes and inspectors are wrong sometimes (they are, ultimately, human) but the inspector, by definition, cannot be wrong. Make him happy and you get your sticker. Go fix the thing he made the electrician do wrong once you have the sticker.

 

[azjohnny]

There is no plug/receptacle rated at 60A, in no small part because code requires anything over 50A to be hardwired.

There is such a thing as a Nema 14-60. Wattzilla has that as an option for their Black Mamba portable EVSE

 

[ajdelange]

I'm removing this post because I have found that it's recommendation was not compliant with NEC 2020

 

[courtier]

Well, I'm glad to see my question fostered some healthy debate. ;-)

For now I think I'm going to have an electrician run a 60a circuit to my parking spot but leave it unterminated (and breaker off, of course). Later, when there are more details available from Rivian -- particularly if they are going to offer a Rivian-branded EV charger -- I'll complete the install in time for my delivery.

Thank you to everyone offering suggestions and input!

 

[DucRider]

I guess I was too narrow and looking only at the codes for EVSE installation. I hadn't seen the 60A before

NEC 625.44 Electric Vehicle Supply Equipment Connection.
Electric vehicle supply equipment shall be permitted to be cord and plug connected to the premises wiring system in accordance with one of the following:

(A) Electric vehicle supply equipment intended for connection to receptacle outlets rated at 125 volts, single phase, 15 and 20 amperes.
(B) Electric vehicle supply equipment that is rated 250 volts maximum and complies with all of the following:

(1) It is installed indoors and or part of a system identified and listed system as suitable for the purpose and meeting the requirements of 625.18, 625.19, and 625.50 and 625.52 shall be permitted to be cord-and-plug connected.
(2) It is intended for connection to receptacle outlets rated no more than 50 amperes.​

 

[ajdelange]

I am, at this point, quite confused. You can clearly easily obtain 14-60R receptacles and Wattzilla offers 2 UL listed chargers (the Black Mamba and the Wall Wattz) that ship with 14-60P plugs and yet the code as quoted above and in the 2014 edition (the latest I have) make it pretty clear that you cannot use either of these. So we have the paradox of UL approved equipment that violates the NEC if used as intended. My only conclusion is that the 50 A limitation must have been removed in the 2020 edition and the only way to find that out is to spring for the $100 and get a copy which I did. The 2020 code is even more restrictive:

"(3) A nonlocking, 2-pole, 3-wire or 3-pole, 4-wire grounding-type receptacle outlet rated at 250 volts, single phase, 30 or 50 amperes"

I'm an engineer, not a lawyer, and to read the code you need to be a bit of both really but I don't see any way around this restriction that stays within its intentions. The implications of this are two. First, if you install a 60A receptacle the inspector may catch that and fail you. If he doesn't (and they don't always catch everything) the risk is that should something go wrong your insurance company has grounds for denying any claim and they will.

I've written to Wattzilla in the hopes they can clarify and will report back here if they respond.

As to what I'd do in OP's shoes? I think I'd pull wire adequate for 60 A and connect it to a 50A breaker and install a 14-50R. Should it turn out that it is possible to connect the 48A Wattzilla chargers legally this is easily modified by changing the breaker and the receptacle.

 

[electruck]

The 2020 code is even more restrictive... I've written to Wattzilla in the hopes they can clarify and will report back here if they respond.

Thanks for digging into this for the rest of us!

 

[ajdelange]

You may all think I have a strange mind but I actually find this sort of thing interesting so mon plaisir.

I've been thinking about possible approaches that would allow the use of the Wattzilla units (very popular among the non Tesla crowd but they are rather dear). Here's what I am thinking about doing.

Install a 60A circuit that is, 60A breaker, 60A wiring, 14-60R receptacle. There is absolutely no code violation in doing that. The code violation comes when you connect EVSE to a receptacle other than one rated 30 or 50 A. If the inspector says he can't pass the installation because he knows you are going to be connecting EVSE point out that the 14-60R is, in fact, a 50A receptacle because the hot (X and Y) and earthing (G) blades are the same dimensions (0.5" x 0.1" and 0.3" ø respectively) as in the 14-50R (and 14-30R for that matter) and the only blade that differs between the three (W - the neutral) is not connected. Inspectors come with a wide range of understanding. If you get a smart guy he will understand and probably approve. A huge help is having an electrician that has a good working relationship with the inspectors and, of course, having a good electrician also helps. Good electricians are hard to come by and the only real way to tell if you have one is to work with him.

The basis of the argument here is that the code requires connection with a 30 or 50 amp receptacle and a 14-60R is, with W not wired a 50 A receptacle (and a 30 A and a 60 A too). If your inspector buys that argument then Bob's your uncle and a good way to get an idea as to whether he might is to bring this up with the electrician who will do the work before committing. If he says "Oh sure, we do that all the time." then there should be no problem. I'm sort of expecting that Wattzilla's position is something like this but we'll see what they say if they answer my query.

Now should the inspector be a "book man" have the electrician take out the 60A breaker and install a 50 A one and replace the 14-60P with a 14-50R. He'll have to pass that. There is nothing wrong with having wire bigger than the minimum required by a circuit. It's pretty obvious what you do after he leaves but understand that you might, in the case of an insurance claim, wind up having the same conversations with the insurance adjuster and eventually in court so that if you aren't prepared to handle that then just stick with the 50 A circuit and buy the 40 A version of the Wall Wattz or Black Mamba.

 

[DucRider]

Just hardwire it so it meets code. Also has fewer potential failure points at the connection
I haven't unplugged my EVSE in 6 years.

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