As for the plug-in testers, the only people I see use them are home inspectors by us. Unfortunately, the readings they get with them cost some poor homeowner a service call by me. The results they get just don't seem to be correct very often.
If an electrician can't figure out how to use real testers, they should do some other kind of work. And it doesn't look to professional walking around with one of those either.
I will use one to try and cypher what a home inspector was getting as far as eroneous readings.
If a receptacle had a ground wire from a box tied to the ground screw, and also to the neutral screw, would not the readings be correct on the tester? And no neutral in the box to begin with.
Then comes the voltage issue, real testers will show it is more than 120V.
Now, you folks bring up the issue of lower and higher voltage in incorrect locations. I always make sure that the two shall never meet. 208/120 in it's own runs, 480/277 in it's own runs. Indicating the higher voltage on j-boxes in some locations as a safety precaution for future reference is sometimes nice too.
NonLinearLoad
