I installed a new switch for a new ceiling fan. For power, I pigtailed the 3 wire cable to my new switch from an existing light switch.
My problem is with the newly installed ground cable.
The 2 existing ground cables are screwed to the metal box at the back, each on their own screw.
What do I do with the 3rd (new) ground cable?
When I connected to either screw at the back of the box (where the other grounds are connected) the breaker pops. If I leave it unconnected the breaker is fine and newly installed switch works the fan.