Unfortunately there's been a "gold rush" in EV charge station installation, and this grade of work has been typical.
Tying neutral ground ("protective earth") has been illegal since 1999 for reasons seen in this video of UK practice (they have only one live wire; note how GFCI/RCD is useless). Fortunately, your installer did run 4-wire cable from the panel to the subpanel, so this is as simple as adding an accessory ground bar (panel labeling lists models made to fit pre-drilled sites), moving grounds to it, and removing any neutral-ground bond which may be installed.
I don't see a ground wire on your added circuit - that is concerning.
The EV charging circuit is a pastiche of all the novice mistakes with EV charging.
- Use of a socket. Early EVs were provided with a "travel" charging kit. On the road, what's your best bet for finding big power? CGP Grey explains it here at 11:15: RV parks and the large-RV 14-50 socket. Home charging was expected to be hardwired wall units, and sockets add failure points - especially with ...
- Use of 40-60A class charging at home. When filling every night, that much power is "totally bonkers" overkill, as Technology Connections discusses at 28:15 in their superb primer on home charging.
- 6 AWG NM-B "Romex" cable used for 60A charging. No, it's only 55A wire due to its cheap insulation per NEC 334.10. This problem is exacerbated because (due to wire bending rules) almost no wall unit EVSEs accept #4 wire.
- In your case, a 60A breaker on a 50 amp socket, forbidden by NEC 210.21.
There are additional mistakes we can guess, because they are so often made.
- I think you dodged a bullet on a GFCI breaker since it became code generally for all garage and outdoor sockets only in NEC 202. However, some states did adopt NEC 2017 TIA 17-2, which demands GFCIs for EV station sockets.
- Failure to use a torque screwdriver to tighten ALL connections per NEC 110.3(B) "follow instructions". Only recently has science proven torque matters on terminals this small, and a huge number of electricians and pretend-electricians still do not believe it, so it was restated again in 110.14(D). But again, history of EV charging has shown us lots of meltdowns likely or proven to be torque related.
- Failure to do a Service Load Calculation, generally inspectors want to see NEC 220.82... to determine whether the electrical service is capable of supporting EV charging directly. If that's a problem, don't panic - EV charging was designed for exactly that situation, and there are sensibly priced answers that are REALLY cool!
- Use of a cheap under-$30 NEMA 14-50 "range" outlet. While screw torque might play a role here, we've seen statistically significant data to condemn ALL cheapie, under-$30 NEMA 14-50 "range" outlets. You need to use the RV-park grade 14-50s.
The spotter's guide for RV-park grade 14-50s is if you can draw a line between 2 screws without hitting the socket, it's a cheapie. The RV park grade sockets have a larger diameter and need a larger cover plate (always adventuresome to find!)
So your action items are (sorry for all the lists)
- recheck the service Load Calc (note: if you have only the usual 4 appliances of range, dryer, water heater and A/C, and your breaker says "200A" on the handle not "100A" twice, then no need. If the Load Calc is a problem, come back and let's talk EVEMS.
- Re-torque everything.
- Determine cable type and affirm its max amps. #8 NM and UF (Romex) = 40A. #8 anything else = 50A. #6 NM/UF = 55A. #6 anything else = 65A.
- Change breaker to 40/50A... OR.... go to a hardwired wall unit that supports 80% of the wire rating. Emporia being the only unit that supports 44A for 55A wire (at our request actually) and also supports EVEMS.
- Review your state's adoption of NEC 2017 TIA 17-2 and use GFCI breaker if required. QO GFCI breaker - ouch - I'd rather put the money toward a wall unit.
- Review your socket type and upgrade to a better socket, ditto, I'd rather put that money toward a wall unit.
Now, I mentioned EVEMS and load calculations. There are a couple other factors to think about long-term. First, are you expecting another EV? If so, then wall units doing Group Power Management may make sense aka Power Sharing. They split a fixed allocation (e.g. 44A) and split 50/50 when both cars are charging and auto-switch to 100% to the remaining car. Real game changer.
Do you have solar (or are considering solar) on a disadvantageous rate plan such that you get paid significantly less for morning generation (when the car is present) than you pay at night to charge it? If so, Solar Capture (my term) is valuable, which autoadjusts EV charge rate to exactly match what your solar export would be. 80% of your daytime solar is exported (simply because few loads run), so this makes sense. This is an adjustment of that same EVEMS tech.
Any of these issues would drive selection of certain wall units capable of those things.
