Hi, I bought a 30 amp surge protector but seldom ever use it. If I feel that there is a thunderstorm on the way, I will use it. If the storm is already there, I won't go outside and touch the power pole. So it won't get used.
I always have a polarity tester plugged in, in my trailer's kitchen; I also have a Kill-A-Watt that is always plugged in, in my trailer's kitchen. Voltage and polarity is always checked. I made a 30 amp polarity tester that I use at the power post before plugging in my shore power cord.