Quote:
Originally Posted by ghak99
This picture shows the redundancy I was talking about. Note where the green wire originates from on the switch. When you screw the switch to the box with your metal screw you're doing the exact same thing as connecting the green wire to the copper wire and then the copper wire to the box. Of course, the paint and mud work or even moisture can reek havoc on the trust the screw connection requires.
This whole system also ASSUMES your small box conduit grounded system is properly grounded at the big box and that there is no stray voltage in the system or back feeding from a short somewhere in the closed system. Dairy farms and other livestock facilities prove time and time again that a conduit grounded system can do some weird shit. It normally reveals itself when the big box burns itself off the wall and the whole place shuts down. It's why I prefer the wire to actually go back to the bar in the box, even if it's just for my peace of mind.
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Yeah, I just chose that picture as an example of pigtail the ground with copper wire which is code in most areas.
The link I posted and describes checking with a volt ohmmeter to make sure your switch wall box is grounded. It also describes options if it's not.
When in doubt seek an electrician for peace of mind.