Failures in Outlet Testing

By Mike Sokol
www.rvdoctor.com

I've done it...You've done it...We've all done it...plugged a simple 3-light tester into a home or campsite outlet and declared it safe. After all, these $5 testers are everywhere. And you can see from the diagram on top that if you get two amber lights and no red light, the outlet must be wired correctly. That's WRONG!! Possibly DEAD WRONG!!! And here's why.

A few months ago I was experimenting with electrical grounds and contemplating just how 3-light testers work. So I downloaded a schematic and took one apart. As I drew the diagram I noticed something very odd about its operation. While the 3-light tester would be able to identify many circuit problems such as a missing Ground or swapped Hot and Neutral wires, there didn't seem to be any way for it to identify a situation where the Ground and Neutral were both at 120 volts and the Hot wire was at ground. How does this error occur? Let's say you have ungrounded power outlets in your home, office, or campsite that never had a safety ground wire originally. This was common in pre 1970's wiring so it's often found in old buildings. You want "grounded" outlets, so you pay an electrician to replace the old "ungrounded" outlets with new "grounded" outlets.

Click here to continue reading the rest of this newsletter entry from RV Doctor.

This newsletter was sent to 23735 Subscribers