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In alt.engineering.electrical Jitt wrote:
| In article 74683977-6a03-4695-a5a2-
| ,
| says...
| On May 3, 4:38?am, Franc Zabkar wrote:
| Can you elaborate on this by showing us the path taken by the strike
| through the TV?
|
| Path to earth was through the network and into a third computer.
| Through that third computer's motherboard, through modem, and to earth
| via phone lines. Semiconductors in these paths were damaged.
|
| We literally traced this path by replacing ICs. Some ICs (ie
| network interface chips) even had cracks on packages where surge
| current entered or exiting those ICs. Absolutely no doubt as to how
| surge currents found earth ground, destructively, via adjacent
| computers.
|
| I wonder why, since electrical codes in North America
| and Britain require a ground connection at each outlet;
| computer power cords are 3 wire?

What good is having the ground connection at each outlet if it is not used?
Are British power cords for computers only 2 wire?

2 of the wires are power conductors. Usually one of the is grounded somewhere
back along the path to the power system source. But it is possible for one to
have a connection with two hot wires (208V from three phase or 240V from single
phase in North America ... 400V from three phase in Europe ... I doubt any of
those 230/460 single phase systems are around anymore in Britain).

The 3rd wire is the groundING conductor. It is not supposed to carry any
current except in the case of a fault between a hot wire and the case or
frame of the computer (or whatever appliance is involved). While this is
a rare event, it is a more important protection in the case of appliances
that routinely get handled by people more than just being turned on and off.
An electric table lamp might not need the grounding conductor because of the
infrequent handling just to turn it on and off. A computer or cooker would
be handled more than a lamp. A computer would be subject to more handling
than the cooker, but the cooker would be subject to being wet. Both of them
are in far more need of the grounding protection than the lamp.

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