I think a made a big goof!
I was trying to wire a light switch to an existing ceiling light fixture (pull string) in an unfinished room. All I did was run the standard 12-2 wiring from the new switch box up to the existing fixture. Then I drywalled everything up. I went to wire the switch box line up with the existing wiring that leads to the fixture. When I turned things on it tripped and won't properly work from the switch. The pull string works fine (off and on), but when I try using the switch it trips that circuit.
WHERE I THINK I WENT WRONG: I now think that I was supposed re-direct the existing power that ran to the existing fixture in the ceiling down to the new switch location. Then run a separate line of 12-2 from the new switch location up to the light existing light fixture. Am I right? If so, is there a way to rectify this without ripping out the drywall to have the switch and fixture work properly?