I just read about NEC 2017, section 625.54:
"Ground-fault circuit-interrupter protection for personnel.
All single-phase receptacle installed for the connection of electric vehicle charging that are rated 150 volts to ground or less shall have ground-fault circuit-interrupter protection for personnel."
This seem redundant since all EVSE (Electric vehicle supply equipment) have GFCI built into the unit. I was wondering if this refers to the 120v (hot-neutral) type outlet only. I got a regular 40A breaker (2 pole) for my outlet but, if I read this right, I need to upgrade to a 40A GFCI breaker? $100, ouch!
Are 120v (hot-neutral) and 240v (hot-hot) single phase receptacle?
Thanks
Best Answer
If you hard-wire the EVSE unit, then you're covered because the unit has GFCI built in and you never have an open unprotected receptacle.
Presumably you are talking about a residential application in the U.S., since you seem to be doing it yourself and you are referencing the 2017 N.E.C.
This applies whether your 240V supply is single-phase or 3-phase (in which case it will probably be 208V).
As a curiosity, it might be worth mentioning that if you're dealing with a 3 phase service typical of commercial installations (say you're doing this at a rented commercial office or store space rather than at home), then your service is probably 3-phase with neutral, in which case your outlets will either be 120V, or 208V (there is 120V of potential from any of the phases to the neutral, and 208V from any of the phases to another phase).
In a residential situation, you are served by a single phase (from the 3 phase distribution lines), which is stepped down to 240V in the transformer outside your house. This is split, in the transformer, by a center tap neutral into a pair of 120V legs. This means you get 120V from either pole to the neutral, and 240V from pole to pole. But either way it is still only 1 phase.
Sidebar...
The poles of your residential transformer are 180 degrees out of phase with each other, because the AC sine waves are shifted 180 degrees apart. I believe this is one of the sources of occasional confusion, and this plus the fact that both circuits derive from one phase is one of the reasons that some people refer to the 120V legs as "phase legs", and is also why some people sometimes seem to perceive "phase leg" slightly differently than other people. The bottom line is that this entire setup is a branch circuit off of just one phase of the nearest 3 phase transformer that ties you into the long haul power transmission lines that serve you. Thus, the entire 240V circuit that feeds your house, and both 120V legs of that circuit, are all one phase. And yet the two 120V legs actually are out-of-phase from each other.
Summary
But again; if you are connecting the EVSE (Electric Vehicle Supply Equipment) unit to an approved power source, and you hardwire it in, then you are covered by the GFCI built-in to the unit because you don't have an exposed, unprotected receptacle.
If you run power to a receptacle that you then plug the EVSE into, then you're probably required to use a GFCI breaker because you have created a situation where there may be an open receptacle in an area that requires GFCI protection.