Quoted from Atomicboy:
I don't understand this... how is the surge bar not connected to earth ground? It plugs into the receptacle’s ground, which should be a true ground. Any over amping should trip the internal breaker prior to reaching anything past that circuit, for anything within a certain range above what the breaker can handle, anything like a lightning strike will just destroy anything attached either way.
To understand, you have to distinguish between Earth ground and Equipment ground. Earth ground is just that...The ground rod that's buried in your yard. From there, a solid copper conductor goes to your panel box. The distance is kept short for a reason. From your breaker panel, all the romex cables that go out to your outlets, appliances, etc. carry a bare copper conductor but at this point it is referred to as equipment ground. It is no longer directly connected to Earth ground except at the ground bar on your panel box.
So, on those point of use surge protectors, they use Metal-Oxide Varisistors (MOVs) to shunt high surges to the equipment ground. The MOV is kind of like a switch. It sends the high surge from the normal current carrying wires (your load wire and your neutral) to the equipment ground bare copper wire in the outlet. That's fine for transient surges as the path back to the panel box and then subsequently to earth ground is capable of dissipating that short spike of energy. With a lightning strike, if the MOV survives and doesn't incinerate, all that energy is put to the equipment ground conductor in your outlet box. As you know lightning is seeking earth ground. So that energy travels along that copper conductor back to your panel box and then to earth ground via the ground rod. Problem is, your outlet is not point to point to your panel box. To save money, electricians usually put 6 to 8 outlets on a single breaker. So they take that copper conductor to the first box, wire nut it to the next box, then the next box and so on. So, now that copper equipment ground is carrying that lightning surge through all your boxes and anything plugged into them on the way back to the breaker panel.
As for the breaker, there is no breaker on the ground wire. The breaker is only on the load wire. That lightning surge isn't going to trip any breaker which operates on time/temperature as it's travelling along the ground...remember, the MOV did it's job and sent it there.
Oh, and PS.....Guess what happens to a MOV when it does work on a regular transient surge (say your washing machine motor shorts out)? It dies forever and forever never to work again. Think your surge strip notifies you of this....Nope, 90 times out of a hundred it does not, even the 'high end' variety.