Standard 120vac ground-fault detectors measure the current between the Neutral leg of the three-prong connector and the Ground terminal. Any current greater than about 20ma(?) will cause the switch to trip. OTOH, if the load Ground is Open (for example, if a two-prong appliance is plugged in) then nothing happens and power is applied to the load via the Hot and Neutral pins.
The four-prong NEMA 14-50 connector consists of two split-phase 'hots', a Ground, and a Neutral.
Clipper Creek is well-regarded around here and builds an excellent product, IMO, and has lots of experience building EVSEs (I own an older 12A L1).
I presume (but don't know) that their EVSE with the 14-50 connector does indeed look for a current between Ground and Neutral. If one of those legs is open, will their circuit detect that as a fault?
The only way I know of to wire an adapter which takes the three-prong NEMA 10-50P and converts it to NEMA 14-50R is to hard-wire the 14-50 Neutral and Ground pins together. I used to put a low-value resistor between those two pins but realized that I was creating a dangerous situation if the load (EVSE) was utilizing one hot leg and Neutral to internally drive some 120vac circuitry. I have since replaced the resistors with solid 8AWG wires between N and G in all of my three-prong to four-prong adapters. This simulates the house power distribution panel wherein both N and G are tied together at the house power source.
Anyone have a technical comment about why wiring an adapter in this way is in any way dangerous?
With such a dead short between N and G in the adapter, if the EVSE is looking for a current between those two terminals it won't find any unless the EVSE itself has an internal fault (my speculation on that).
Can anyone add some technical input to this discussion?
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV