You probably know that RV campgrounds are notorious for poorly wired power posts.  Too-often they are either aging, worn, or simply incorrectly wired from the start.  Vintage trailer owners frequently notice bad grounds or even reverse polarity.

Make sure you are safe to plug in before you risk your trailer or your own safety.  It's easy.  Just plug this handy tester in first and make sure the LED indicators give you the "all clear" sign. 

Tests for reverse polarity and open ground or neutral.

Plugs into any RV 30A outlet. 

This affordable and handy tester is a must-have in your tool box.