Today at work some hid lights needed to be disconnected from one generator and reconnected to another. The lights were unplugged from a standard 15A receptacle and plugged into a 15A GFCI receptacle. When turning on the lights they tripped the GFCI plug at the new generator. Nothing had changed from the time of disconnect and reconnect. Out of curiosity I took a reading across the hot and ground prongs on the cord end. I got an initial reading of about 700,000 ohms, but that number immediately began to slowly fall. I watched for about a minute as the resistance fell to about 500,000 ohms. It would have been nice to leave the meter on for a while to see where the number ended up, but some people wanted light so they could get back to work. Seeing that the ground leakage appeared to be minimal, I figured that this must be an inherent property of hid lighting. I removed one GFCI plug and replaced it with a standard receptacle, plugged the lights back in, and they work fine now. Why the ground fault? Or is it even a fault? Something to do with the capacitors? The coils? It seems to me that there should be zero continuity to ground. Hopefully somebody can put my curiosity to rest with a good explanation because it isn't making sense to me.Thanks a bunch!Shawn.