Originally Posted by lukeamdman
No. My comment was in response to post #59
where it was said that all MOV-based protection devices contaminate the ground line.
Sorry for the confusion, it only diverts energy to ground when it is protecting against a surge. Which is often just shortly after it dies, assuming the joule rating, voltage rating or current rating was exceeded (which is likely the case in the event of a real surge).
As the name implies, it is a variable resistor, so at low frequencies and low voltages it doesn't do much (in parallel to the load I might add), and at high frequencies and high voltage it converts the excess power into heat and/or ground line noise if/when it enters into shunt mode. (That's my understanding of it at least...)
Normally the hot wire is swinging from 0 to 170v @ 60hz, and the ground line is at near-zero volts and the neutral is also at near-zero volts... as it should be.
Problems only occur when it isn't near-zero or the hot is way higher than 120v rms (ignoring BO/UV for a moment.)
The only way to tell if your HT is experiencing surges is to connect a power-quality analyzer to your wires.
The SurgeX SCP, Envision and Elite have power-quality analyzers built-in and can be connected to a PC for the purpose of monitoring, which is a handy feature. The latter two have basically a built-in o-scope + more.
Here is the LCD screen of the SCP in my cubicle at work. It counts and timestamps the OV/UV/BO/Surge events, similar to a UPS but WAY more sensitive, down to the microsecond level.
Meanwhile the APC 650 I have in my cubicle didn't record any event at all.
In many cases I've been in the room watching the lights dim and the APC and CyberPower units record no events.
No events my rear.
Whole-house mov's only protect against really high voltage surges. They don't protect against brief or sustained OV/UV/BO events. Only the beefier type-3's like TrippLite, APC, Cyberpower or SurgeX etc etc do that. The more expensive units having higher sensitivities and tighter cut-off protections.
(Or in the case of a double online-UPS, it is always on battery, regardless of what the line is doing.)
Ideally we would all have type 1's, 2's and 3's in place. But that's $$$ or $$$$
There does exist 30A type-3 SPD's, but they often cost as much as a FP14k clone... if not more!
Type 1's and 2's don't (usually) have this current restriction because they are in parallel with the load, so the load could be the full 200a or 400a or xyz.