First up, my credentials: I've purchased many surge suppressors, and installed a whole house one. Read up on them on the internet.
Fistful, the product in question is a standard permanent mount suppressor, and is wired like pretty much every other AC suppressor on the market.
Even my whole house unit is only four wires, and utilizes a 20A 2 pole 240V breaker. One wire to each hot, ground, and neutral.
The way to look at it is that a surge suppressor doesn't actually BLOCK over-voltage. What it does is operate in PARALLEL with the operational part of the circuit - your lights, the computer, whatever.
As long as the voltage stays below the clamping voltage(320V in your unit's case, standard), it attempts to look like an open circuit - infinite resistance, no electricity passes through it.
If a surge happens, the voltage rises above 320V, it attempts to look like a short - no resistance, straight to neutral(or ground). That's why they're rated in watts - They can only have so many.
Think about how the lights in some homes can dim when you turn on a high power device like a vacuum. Even though the circuit is supposedly parallel, so amperage should go up but voltage stay the same, in practice there are limits. So the excess voltage and amps, rather than all going through your device that doesn't like that sort of treatment, it goes through the surge suppressor, which while it doesn't like it either, is at least built for it and is normally cheaper to replace.
