Installing a GFCI Outlet in Vanity in Bathroom... Ground Wire Issues....

[Michael Miller]

Yesterday, I was trying to replace a very old 3 prong outlet near the vanity in my bathroom. For some reason, the Green Ground wire came all the way unattached from the inside of the wall. It appears to have some kind of connector on the end where it came lose from inside the wall... 1st Question:

Is the Green Ground wire absolutely necessary in the operation of the GFCI Outlet working properly, cause when I tried connecting the connector to another copper wire that had the same type of connector on it inside the wall, something sparked for some reason and shut off all the power in the east side of my apartment. For some reason that particular outlet near the vanity has it's own breaker in the breaker box... But for the rest of the area, the east side of the apartment (the bedroom) There's a separate breaker that shuts off EVERYTHING in the bedroom, including in the bathroom, except for the particular outlet that I'm working on........ Is the green ground wire necessary? Can someone please help me out in this situation... Cause this just has me completely confused, especially when that breaker for that outlet was shut off... I don't even understand how it could have sparked at all, shutting off a whole separate breaker, when that breaker was turned off, and shouldn't have had any type of current running through it, I would think...! ??? Any suggestions anyone???

Thanks,
Michael in North Hollywood, California, 91601