Back in the 2004/5 time frame the Progressive Industries EMS HW 50C was the gold standard for 120 vac power protection. I installed mine at the coach end of the power cord. My coach was saved from several power surges including open neutrals, induced voltage from close lightning strikes, low voltage, high voltage, to name a few. We full timed from 2004 until 2010 when we purchased a home and sold our Windsor. Back then when the 50C was damaged by any power issue, PI replaced the unit free.