Have been thinking about this a bit, and realize I'm probably looking at it the wrong way.
The other night we had a moderate lighning storm come thru. Momentary loss of power; perhaps a few seconds.
The only damage was to a newly installed furnace's circuit board which got fried. It obtains it power in the normal way, via a hard wired, dedicated,110 V branch back to a dedicated circuit breaker on the main panel.
The surprising thing is that nothing else was damaged; even the PC worked fine afterwards.
So, my questions are -
Let's assume that there is only only one cheap extension cord outlet strip in the house that has MOV's for protection, and that the PC was plugged into it.
Let's also assume that it was connected to the L1 side of the 110V coming from the Service Box , as well as perhaps a dozen or so other circuit breakers and branch circuits. (the 220 V service coming in being split into two 110 V sections, L1 & L2)
It would seem to me that the MOV's in this strip, assuming they work(ed) really well would protect anything upstream just as well as anything plugged in downstream (like the PC's) as all they do is clamp the line to gnd. Upstream or downstream should make no difference. Is this correct ?
By the same reasoning, I could argue that All the branches on L1 would be equally protected by this single MOV strip, as all of L1 would get clamped. I guess there would by a few nsec difference in propagation times for the surge of the different branches, but it's hard to believe this would effect anything.
Are all branches coming off L1 equally protected by a single strip on just one of the branch circuits, do you think.
Obviously the MOV strip it didn't protect the furnace circuit which was on L1, so I am probably wrong about this.
Any thoughts on this would be most appreciated.