[Amps] MOV Sizing

[Paul Christensen]

> MOV's should never tie to the safety ground lead or any ground lead 
> outside of an entrance panel.

That makes a lot of sense.  Some of the sources I've read recently advocate 
not using ground as a MOV reference for that very reason.  High current 
surges may follow other grounding paths (coaxial cables, audio shields, 
etc).  But there are sure a lot of commercial MOV devices that offer "all 
three modes of protection" with a ground connection.

Several manufacturers divert to a neutral when available, rather than ground 
to avoid the above problem, presumably to route the energy to ground at the 
neutral/ground common tie point at the service entrance.   Probably my best 
alternative above and beyond the "whole house" device is to use a single MOV 
across the 240VAC line and skip the MOVs from line to ground.

Paul, W9AC