Switching lights on and off or using the garage door could cause a lot of line noise, which will make the EVSE just flat out stop charging. That EVSE is going to chew up 12 out of 15A already, so I wouldn't risk it. Also, the EVSE has built in GFCI, so there's not really any need to put a second one in circuit. When I was running mine on L1, I installed a Leviton outlet that had built-in surge protection. What year is your Volt?