In your travels you will eventually run across a campground that has problems with its electrical power or have an outlet that's been wired backwards or the ground has come loose. Or you may just have a power surge from a local storm. What Denny and I have found handy are the following items:
A digital monitor of some sort. This one pictured below plugs into a wall outlet. I have mine plugged into an outlet on our kitchen island that I can see as I enter the rig so I know if there is a problem as soon as Denny plugs in the 50 amp power cord. There is not only a read out on the screen showing the problem but an alarm sounds to get your attention.
In our current fifth wheel our 50 amp power cord is on an electrically powered reel; you push a button and the cord rewinds itself for travel. While these are wonderfully handy, they can also cause a problem if you just allow the cord to be pulled all the way in by the power winder, which can cause the plug end to be pulled/dragged against the roller brace. That in turn can pull on the plug and loosen the wires, which we have discovered to our chagrin. Our original power cord looked like the one pictured below, but we had a bad plug which allowed a lot of voltage to go through our electrical lines and that in turn fried the electronic devices in the rig that had "instant on" connections like the TV, microwave, DVD player, Wii as well as our central vac and washing machine.
We took the trailer to a local Heartland dealer for the repair to the electrical system and they replaced the power plug with one made by Camco which looked similar to the ones pictured below:
Now some of you will say, "but Linda, don't you have a surge protector on your power cord?" And yes, we do. However, the outdoor surge protector is only good for protecting you if the power source from the campground is bad. If your own power cord is bad or has broken wiring inside it, that problem starts after the surge protector and therefore is not protected by it.
So; external surge protector for the campground power post/outlet, digital voltage meter of some sort to quickly check the quality of the electrical connection to the campground's power supply, internal individual surge protectors on those outlets that will have valuable and sensitive electronic equipment plugged into them. Believe me, the cost is a lot cheaper than replacing a bunch of appliances and electronic equipment--we know.