Surge protectors/suppessors wear out over time and need replacing even though the Monitoring System still functions. Most electrical spikes are less than a 100 Joules. Small spikes overtime cause the MOVs (metal oxide varistors) in the suppession devices to short curcuit. Most RV plugin devices are rated around 900 Joules. Each time an MOV shorts the protectors/suppessors loss capacity and life expectancy.
If a surge protector has a rating of 4000 Joules, (8x20μs) and another has a rating of 2000 Joules (8x20μs), then the 4000 joule protector has a life expectancy 10 times greater than that of the second protector. Joules matter!
An important feature of a good surge protection is the clamping time. Clamping time rating needs to be around 8-20 nanosecond, (20us), some RV devices are as slow as 1 mil second before the curcuit opens & removes power. The damage is already done before the device reacts. Check rating before buying.
https://static1.squarespace.com/stat...97719/TOTM.pdf