Hi all, I'm a DC circuit man myself--industrial maintenance--I can look at a machine and figure out whats wrong, but at least we have schematics on the rare ocassions I get stumped. My problem is I went to turn off the lights in my home and slid the dimmer switch and the wall lights would not turn off. Figured it was a bad switch so I unscrewed the bulbs. Bought a new switch a few weeks later, figureing twenty minutes at the most. Took off the first wire off the dimmer and the lights were still on. Took off the second wire and the lights are still on! Its in a room addition where they used 3-wire outlets,the rest of the house is of the 2 wire variety. There are 3 romex cabels into the switch box of two dimmer switches for 2 seperate lighting circuits. One has no power which went to the lights that worked correctly. Another has a hot white wire(120v), and the last romex has 120v to the white AND 120v to the black wire as well! Traced the wires to another j-box, when i unhooked the ground wire from the cover plate, the lights went off. Circuit tester, of course, says hot and ground reversed. I do recall hearing a pop-pop while watching TV, but everything worked for weeks after. I guess my question is: do I have evil rats or gremlins and is my house ready to burn down? Help!

 

Most dimmers will not dim all the way to off. They usually have a separate on/off switch in addition to the dimming control.

You were working on it hot?!?!

Indication of an incredibly unsafe installation. You are correct to be concerned.

99.9% of the time, a hot/ground reverse on a tester is a false indication of an open neutral.

Probably closer to the latter than the former. I would have an electrician come investigate.