>IF using a 130 V rated MOV, where does it get wired ? Do you wire
between 120 vac and neutral.... or 120 vac and chassis of equipment in
question ? IF a spike / transient / glitch etc occurs.and MOV
conducts..which path do you want the fault current to flow through, the
ground wire or the neutral ?
Jim,
I place MOVs between line and neutral when a neutral is accessible. As you
point out, Neutral and ground are tied together at the service entrance.
If a high-energy transient is impressed on one of the line conductors, I
would rather divert the current onto the neutral since it's a grounded
conductor meant for current. If the MOV is placed from line to GND, a
high-energy transient can cause the ground potential to rise, sometimes
unevenly, depending on bonding quality. It's probably not an issue with
well-bonded systems, but daisy-changed grounds in a typical home don't
create a well-bonded path all the way back to the service entrance. That
GND in a home is there for safety, not to divert high-energy transients.
OTOH, since we discuss amps here, most of us probably have "home runs" from
the shack 240VAC receptacle all the way back to the breaker panel. And,
most ops probably don't run a neutral so it's L1-L2-G. In that case, I see
no problem running an MOV from line to GND. I always suggest running 4-wire
service to any new amp receptacle if there's any possibility of using an
older commercial amp with a 120VAC blower.
In my home, a "whole house" surge protector is installed at the service
entrance. MOV secondary protection is only used on select receptacles
between line and neutral.
Paul, W9AC
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