David wrote: >True, grounding the car and using a GFI is of some help. But what about >those times when you're charging somewhere and can't get a good ground? And >how many BC-20 owners have cheated the GFI so they could get a charge in >spite of the leakage current it was detecting?
When you have *both* GFI and a grounded frame the car will not shock anybody. As soon as the ground leakage hits 5ma (20ma is the max level considered safe) the GFI trips. Any potential ground leakage contributes because the grounded frame gives it a path that isn't one of the two power conductors (this is where a GFI device looks for the 5ma difference). If your relying on isolation to make your charger safe you have a safety system with NO redundancy. You need to use 2 layers of safety to provide proper protection for public charging IMHO. Transformers can and do fail. I know of 3 safety devices that each provide a layer of safety, please use no less than 2 for public charging. The choices I'm aware of are, isolation, earth grounding the vehicle, and GFCI. If the ground fails (or perhaps you plugged in somewhere where the ground wires aren't hooked up), the GFI still provides protection. You can get a slight tingle without tripping it if you have leakage paths, but if that tingle hits 5ma the GFI trips (ground fault). If the GFI fails a grounded frame will still protect you. It will pass back all the ground leakage current, and if its really bad (a short) the service breaker will blow from the current. Any safety device needs to be tested. Have you checked to verify that your isolated charger is still isolated? I do check my Buggies (and its cords) grounding resistance. I do test the gfi device. My Buggy is only electrifying to drive. Neon
