While in the marina in Puerto Chiapas Mexico, I gave a fellow cruiser a hand moving his dinghy in the dry storage yard. To move it, we had to move the aluminum ladder used to get aboard. When we went to use the repositioned ladder, we got a strong electrical shock. After getting another boater in the yard to unplug the boat, we came down and I fetched my “circuit tester” and we used it to test the outlets and boat wiring, finding a “hot ground” condition in the marina outlets.
Since any wiring fault can be serious; cause shocks, damage equipment aboard, dissolve zincs, etc. I use this simple tester in every marina we enter. While most marinas in Canada and the USA are ok, I think about 1/3 of the marinas in Mexico have failed somehow in their wiring. The marina management has always quickly set the problem to rights when informed, but if they don’t know it’s broken they won’t fix it.
This simple tester doesn’t do anything you can’t do with a multimeter, but it is simpler and faster to use, has the advantage of instant readout (no switching the leads around), and no chance of a zap from the leads as you use them.
We have lent it to dozens of cruisers in different marinas after they see us get the management out to fix a problem, and all comment that they are adding one to their box of tricks aboard.
These are available at most good hardware stores, in the $10-20 range.