NEC 210.19 and 210.20 state that Overcurrent protection devices and conductors need to be sized to 125% of the load when the load is continuous... Or that the load must be 80% of the breaker and conductor rating when continuous, depending on if you like division or multiplication better.
48 is 80% of 60.
60 is 125% of 48.
Any way you slice it, one needs a 60 Amp circuit for a 48 Amp EVSE.
NEC 625.13 I think limits cord and plug installations to 50 Amps circuits. 60 Amp EVSEs need to be hard wired.
Is OpenEVSE offering non NEC compliant hardware or am I reading the code wrong?
Doesn't NEC require EVSE to be listed? So, is any of this actually relevant to OpenEVSE since it's not listed?
See this thread at the Mike Holt NEC Code forum on this topic:
The plug connected EVSE needs a GFCI to protect the bare outlet if the plug is removed:
meter->main breaker->dedicated breaker->premises wiring->GFCI->NEMA 15-50
meter->main breaker->dedicated GFCI breaker->premises wiring->NEMA 15-50
In short the hardwired EVSE may or may not need a GFCI
meter->main breaker->dedicated breaker->premises wiring->EVSE w/GFCI->cable->J1772 plug->car
A relevant video shows a Zappi tripping at 6ma current, which would make it the GFCI for NEC purposes, maybe:
RDC-DD 6mA Testing of EVSE Charging Stations
The experts don't seem to have a single conclusion based on Mike Holt.
Does OpenEVSE trip on a RDC-DD test of 6mA or less?
OpenEVSE built in GFCI is UL CCID 20, it trips between 15-20ma. CCID 20 is the most widely used GFCI standard because 6ma has been found to be too sensitive when pulling thousands of watts continuously.
The latest NEC code is in conflict with UL standards and years of EV charging experience. NEC now requires a 6ma GFCI on the NEMA receptacle which WILL cause nuisance trips and headaches.
The ground monitoring required by UL leaks a few ma to verify ground. 6ma trip point minus lets say 4ma intentional leakage to verify the ground path results in actual trip point of 2ma additional leakage. Thanks NEC for being a huge nuisance to EV owners.
The NEC requirement is for a NEMA outlet is:
meter->main breaker->dedicated breaker->premises wiring->GFCI 6ma->NEMA 14-50
The UL EVSE Requirement is:
plug -> Ground Monitor (few ma intentional leakage)-> Relay Disconnect -> GFCI 20 ma -> EV Plug J1772
Put them together:
meter->main breaker->dedicated breaker->premises wiring->GFCI 6ma->NEMA 14-50 -> plug -> Ground Monitor (few ma intentional leakage)-> Relay Disconnect -> GFCI 20 ma -> EV Plug J1772
The conflict and nuisence trip is in RED.
If UL, SAE and NEC actually worked together back in 2010 the optimal solution would be for ground monitoring to happen as far downstream as possible and GFCI as far upstream as possible.
meter->main breaker->dedicated breaker GFCI 20ma-> premises wiring-> NEMA 14-50 -> plug -> Relay Disconnect -> EV Plug J1772 -> Vehicle - Ground Monitor (few ma intentional leakage)
There are a number of cases where installing a panel mounted device or any sort is difficult or tremendously expensive. For example with a tandem 50/30 amp breaker not available with any form of GFCI or AFCI.
The GFCI requirement was justified by a death of a child who jumped over a fence onto an HVAC condenser, damaging the condenser, and creating an electrical fault to the case of the condenser. However the report is disputed in part because the case of the condenser was not grounded: GFCI was not needed to prevent that tragedy.
Either way the Holt forum is one of the informal ways to discuss what might eventually turn into code change via a TIA or in the next edition of the NEC. As it stands it IS NOT CLEAR that HARDWIRED EVSEs require a GFCI at the panel or shutoff. But plug and cord connected ones clearly do.
The Mike Holt forum listed above is special, in that many of the members of the NEC revision working groups
hang out and discuss code changes there.
Consider posting your experiences in that thread:
It does no good to argue that the 2023 NEC requirement is wrong or vague (though it is).
The only way forward is to either try and make the Class A 6mA standard work, or get the committee to issue a TIA to modify the 2023 code before it takes effect.
That sausage is also made here:
NEC® Correlating Committee Second Draft Task Groups Schedule (A2022)
Guests: For access to a meeting please contact Sarah Caldwell and you will be
put in contact with the Chair. List will be updated as meetings are scheduled. Meeting dates/times are
listed under the Task Group number and Chair.
Code-Making Panel 1 – Ken Boyce, Chair
Task Group 1: Ernie Gallo, Chair Article 90, Annex, Globals
You are reading the code right. NEC has added a bunch of new contradictory rules in their latest version.
NEMA 14-60R are technically prohibited by NEC in the US.
Also NEC now requires GFCI on receptacles including NEMA 14-50 which is too sensitive for EVs pulling many thousands of watts at 6ma. The standard for EVs is 20ma.
Additionally, NEC now requires all stations with adjustable current to be hardwired, essentially eliminating just about every plug in station on the market.
The latest NEC is a mess for EV charging, contradicting many established standards by others, including SAE J1772 and UL 2231.