w_tom wrote:

On Jul 12, 9:04Â*am, "CL \"dnoyeB\" Gilbert" wrote:
I don't follow this example you keep giving. Â*Seems like your saying a
device adjacent to a protected device got damaged!?

IEEE example on Page 42 Figure 8 shows a protector too far from
earth ground. A surge was not earthed (energy diverted into earth)
before entering the building. So the surge arrived at a plug-in surge
protector. What do surge protectors do? Shunt (distribute, connect,
clamp) that energy on all other wires. Well, that surge still must
find earth ground. Since the wire back to the breaker box is maybe 50
feet long, then that surge voltage is so high as to find another path
to earth: 8000 volts destructively through the adjacent TV.

In an obvious example, lightning incoming on AC electric was shunted
to all other wires by two plug-in protectors. Surge on the black wire
was shunted to the green wire, into two adjacent, powered off
computers, out via NIC cards, into a third powered off computer, and
to earth via modem and telephone line. We literally located and
replaced every IC that conducted the surge to make all computers
functional. Surge not earthed at a service entrance (no 'whole house'
protector) means a surge is inside the building finding other paths to
earth. In this case, surge found earth ground via three powered off
computers because the plug-in protector connected an AC hot (black)
wire surge directly into computer motherboards.

If the computer was off then there should be no current path through it.
You mean it was in soft-off mode.

Furthermore, you gave your whole argument away when you introduced the phone
line path to ground. most likely that is where it entered. A phone line
does not provide a better path to ground than the house ground..


Sure the surge gets dumped from one wire (say black) into another wire in
the suppressor. However, the other device is also connected to the black
wire and it already has to deal with the surge with 0 protection. The
devices are already parallel. So I fail to see how this adds anything to
the other device being damaged.

Since we have 3 phase power, lets say the surge came in on 1 source wire.
Then the surge was attempted to be dumped into ground/neutral. Some of
that current can pass into adjacent device if ground/neutral cant sink all
the load. So we are back to the question of the quality of the main path
to ground vs. other paths. And the 3 phases should only mix in the fuse
panel or at 220 devices.


I think you misinterpreted the example. Probably it was talking about
surges entering on auxiliary lines like Cable and phone. I agree a
cable/phone surge suppressor is going to potentially introduce components
isolated from the phone/cable line to surges that came in on the
phone/cable line. Again, to the degree the ground can't sink the load.