electricallighting
My metal wall box has line, load, and neutral wires, which I've identified.
My understanding:
Where do I attach the green (ground) wire?
In the back of the box there are two screws securing bare copper wires.
Can I secure the green wire to one of these screws? Is it okay to have two wires under one screw?
Wiring diagram for Leviton PR180 3-Way Wall Mount Occupancy Sensor.
The loop in the black wire is normal when electricians are running a hot wire from device to device. It saves them time and is really safer since it involves fewer wire nuts.
The orange wire is the wire that is going to the light. The power enters the switch where the black wire is looped over the screw, and exits to the light through the orange wire.
Yes, attach the green wire to the green screw. But, you need to wire the blacks from the switch differently. One switch black is for the incoming power, and the other is for the exiting power. So, one needs to be connected to the same black that is connected to the old switch; and one needs to be connected to the orange.
I would, with the power off at the circuit breaker panel, and after testing to make sure the black at the switch is not hot, cut the existing black to form two separate wires and strip the ends appropriately. Then I would connect one of the black wires from the new switch to these two wires with a wire nut. After that, connect the other black for the new switch to the orange with a wire nut. That should do it, and your dimmer should now work. Good luck, and be careful!
PS: I personally use a Fluke 1AC-A1-II Volt-Alert AC Non-Contact Voltage Tester to verify or locate hot wires and love it. You might want to check it out for the future. Its inexpensive too. Note: I have no personal connection to Fluke; I just think good products like this are worth spreading the word about.
Best Answer
The green wire does need to connect to one of the two grounding screws in the box.
To completely comply with code practice, you would only place one wire under each grounding screw, but unfortunately the previous electrician has cut off the ground wires of the existing cables too short to pigtail a wire connector to them. You could try loosening the cable clamp and try to pull the cables far enough into the box to provide a minimal ground conductor length (if careful, you may only need 2-3 inches), wire nut them together, and connect one conductor to one of the grounding screws. (Don't forget to retighten the cable clamp.) Then connect the green wire from the dimmer to the other screw. This arrangement allows the dimmer to be removed without opening the grounding connection to the rest of the circuit.
If neither of the cables has enough slack outside the box to do that, then you should still run the green dimmer wire under one of the two grounding screws, but it's not a best practice.