Originally Posted by avanti
Please note that EACH AND EVERY such device has an indicator to show when the device has suffered sacrificial damage and must be replaced.
Again, that light can only report one type of failure ... that is catastrophic. Sacrifice must not happen. That indicates the protector had to disconnect protector parts as fast as possible to avert a human safety threat. And leaves a surge still connected to attached appliances.
A surge that damaged a grossly undersized protector was also outgoing into attached appliances that remain undamaged. Because protection inside the appliance was more robust.
Normal failure mode for MOVs is to degrade. Not fail catastrophically. MOV manufacturers even state how to test an MOV's Vb change.
The change of Vb shall be measured after the impulse listed below is applied 10,000 times continuously with the interval of ten seconds at room temperature.
It did not fail catastrophically. Normal failure mode is to degrade. The light can never reprot a degraded protector. It can only report a thermal fuse averted the unacceptable catastrophic (sacrificial) failure.
MOV protectors, when properly designed, only degrade. Its Vb voltage changes. Its light never reports that acceptacle type of failure.
This is relevant only to RV surge protectors located at the pole. Since MOVs only avert that anomaly when connected low impedance to an earth ground provided by the pole. Instructions for this RV protector
http://trci.net/products/surge-guard-rv ... -protector
state it must attach directly at the pole.
Other RV "surge protectors" are for anomalies not considered here as surges. Therefore need not be attached so close to earth ground.