It is essentially a neon bulb with two leads going to it that gets brighter with increasing voltage across it. Always start out by testing a 120v wall outlet live with the small lead kept pressed to a known ground while the big probe makes contact with any metal in each remaining slot in turn. Or just plug a small reading lamp in it and turn it on. Then go turn off the power and the lamp should go out.

A better choice if you have more work to do is buy a cheap digital multimeter and a cheap analogue multimeter. That way you cover all bases and don't get caught in a "But I thought" situation.

This post was edited by laat2 on Fri, Mar 8, 13 at 21:42

All I need to do is pull the outlets out from the wall a bit and slide in some pvc box extenders so I can install a tile backsplash, I'm not deliberately going to be touching the wires or doing any wiring - I just don't want to get zapped working near them! There are 4 outlets and 2 light switches.

So I put the small lead into the ground hole and then test each prong of the outlet separately? The lamp test does seem easier and I had thought of doing that, but not sure if I was missing something regarding the safety.

Check the two slots in combination. If you want to be real secure, check the slots with respect to the ground pin (or some other known ground).

Hi, If you want to turn the power off when you do the work on the boxes. Turn the lights on, plug a radio in turn it up loud go to the breaker box listen to the radio, if you can hear it shut the breakers off untill the radio stops. Go back to the room check the other outlets with the radio. If the lights are on trip the 15 amp breaker on the breaker box.
Good Luck Woodbutcher