How to protect against poor RV park power?

Every summer posts appear concerning low voltage at 30A sites and more so in older or non maintained parks. Not many posts for 50A sites.

Yes a EMS will detect and shut down with low voltage and no more A/C. Another solution is a autoformer that boots voltage.

I suggest you get yourself a Progressive Industries 30 amp EMS. It will drop out (cut off power) if there's anything wrong with the supply. Armed with that information shown on the display, you can inform the park owners, get moved to a different space, or they'll get someone to fix the problem. I did that successfully several times. Even in Mexico.

But without the EMS, you can usually get a park to let you move.

The rule of thumb is never operate your A/C when the line voltage is outside the range of 108 to 133 Vac. The lower voltages are bad for the A/C motor especially. You should at least have a line voltage monitor inside your RV where you can glance at it before turning on any heavy draw equipment, like the MW or A/C. If it dips too much when you turn something on, there's a high resistance somewhere.

I always carry a spare head for my umbilical cord because those can go bad...especially the 30 amp head. I also carried a new receptacle with me in Mexico and would loan it to RV parks when necessary.

This Progressive 30 Amp

Also available in 50 amp if necessary.