We have a Permanent Surge Guard 120-240V Hardwire 50 Amp 34560 in ours it was about $230 but if you had the Remote LCD for inside the coach that adds another $90 and puts it about the same cost, but you get all the protection for $230 even if you don't add the remote as it has LED on the unit to tell you what is happening without the remote.
Automatically shuts off the power when excessive voltage, Low (less than 102 Volt) and High (greater than 132 Volt), or open neutral is present. Automatic reset on power restoration. Caution indicator light indicates miswired pedestal, reverse polarity and elevated ground voltage. 2 minute 15 second reset delay protects A/C compressor. Fits neatly inside RV´s electrical compartment. 120/240 Volt, 50 Amp unit offers 3,850 Joules of power surge protection.