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musclegeek t1_ixy4yln wrote

MOVs resistance changes inversely to the applied voltage. If the voltage across it increases the resistance decreases and vice versa. They are connected to gnd but have a very high resistance for the normal operating voltage. When the voltage spikes their resistance goes extremely low allowing current to pass effectively creating a short circuit to gnd.

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Xyspade t1_ixzbaia wrote

Thank you! What about when there's only one MOV between hot and neutral instead of a group of three, how does it pass that spike to ground? Or does it just pass it to neutral?

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musclegeek t1_ixzcolo wrote

Neutral is there specifically to handle small surges. Especially in wye configurations and neutral eventually goes to ground. Having it connected to both neutral and ground is a fail safe. No neutral goes to ground, surge too high for neutral goes to both or some large f-up voltage spike from neutral goes to local ground.

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