Hi guys, we have a 'Fixit and Handyperson' discussion database here at work in which a fellow coworker posted the following....

"I have a question related to some electrical wiring I encountered in my house over the weekend...

The light switch for our downstairs bathroom broke recently. It is a combination switch and a receptacle (100V outlet). I bought a replacement switch/outlet. The switch I bought requires 1 positive/hot lead and 2 negative/ground leads. Inside the wiring box in the wall I found 1 solid-core black wire and 2 stranded white wires. Mistake #1 was that I did not carefully note how the old switch was wired before I removed it. Anyway, when I went to hook up the new switch, I assumed that the black lead was the hot one and the 2 white leads were the grounds. However, when I tested out the switch after wiring it up, only the outlet worked (i.e. had power). The light switch did not turn on the light fixture.

Next, I tested the various wires to try and determine what was wrong (after ruling out that the switch itself was defective). What I believe I found is that one of the white wires and the single black wire are the negative leads. The other white wire is the positive one. After I hooked up the switch/outlet with those assumptions about the wiring, everything worked correctly.

So, the basic question is is what I've done safe? I believe that the previous switch must have been hooked up this way (for at least 10+ years) but that doesn't mean that it was done right! Should I have an electrician come and fix this since running new wiring is more than I want to do?"

I responded with the following...

"The solid copper wire is undoubtedly either 12 gauge or 14 gauge, but stranded wires are typically 16 gauge or smaller. Can you find out what the amperage is of the breaker or fuse that is protecting the circuit? And also the gauge of those stranded wires?"

I'm just a home-owner type, but the situation he described seems very questionable to me and I suspect there are other questions to be asked. Anyone want to tell me what those question(s) might be? [Linked Image] Thanks!