devices for surge protection

pianotuna wrote:
Your post caused me to think about what a Mov does. It doesn't stop the surge, it diverts it.

A protector device that is adjacent to the appliance must either 'block' that current or 'absorb' that energy.

If it (instead) diverts current, well, that was also explained.

Assume a surge is approaching on a hot (black) wire that is 5000 volts. What does that protector circuit do. Now that surge is 5000 volts on that hot wire, and 4670 volts on the safety ground (green) and neutral (white) wire. Where is this protection?

If a protector is too close to an appliance and too far from earth ground, then where does it divert that current to? Destructively via some adjacent appliance. An IEEE brochure even demonstrated this in a picture with a number. A protector without an earth ground connected a surge 8000 volts destructively through a nearby appliance ... that was not even connected to that protector.

And that is the point. If that current does not connect low impedance to earth before entering, then nothing can avert a destructive hunt. That current, incoming to everything, selects which item to pass through - destructively.

No protector does protection. Best protection is hardwire connected directly to earth - no protector required. Protectors are used when a wire that cannot connect directly to earth. A protector is only doing what that hardwire does better.

A Progressive that can protect from that anomaly must be located at a pole - to make a low impedance (ie as short as possible) connection to earth ground. Does not matter how good its protector parts are. Even the best protector in the world is ineffective is not connected low impedance to single point earth ground.

UL says nothing about protection. UL (National Fire Protection Association) is only about human safety issues. Protector can be completely ineffective. But still gets UL approval because it did not spit sparks or flame.