ECN Forum Forums General Topics of the Trade General Discussion Area weird mix of wires in box

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? Thanks!

My coworker has posted a follow-up reply to his first post, so I thought I would post it here as well.

"Let me explain a bit better. The switch/outlet is designed to allow for both the switch and outlet to be powered from the same circuit as well as to be powered by separate circuits. Thus, the available connections (screws) are:

Screw 1 - hot lead for the switch
Screw 2 - hot lead for the outlet
Screw 3 - neutral for the switch
Screw 4 - ground for the outlet
Screw 5 - neutral for the outlet

Note that as delivered, screws 1 and 2 are connected by a piece of brass and thus a single hot lead powers both. It's possible to break off a "tab" to isolate these circuits if so desired but I did not do this.

So, as described in my previous posting, I connected the solid black wire to S3, the hot white wire to S1 and the neutral white wire to S5.

The original outlet in the box was not grounded and I don't see any provision for grounding. Thus, I did not use S4. I realize that this is a safety concern. However for now, I'm really concerned about how the switch is wired since I really want to use it. And for the outlet, I can just not use it.

Does this help clarify?"

Your best bet at this point is to call someone for help. Your terminology is somewhat confusing(neutral for the switch), and the smaller gauge wires indicate a serious problem that requires more than just proper re-connection.