Re: Lightning/Power/UPS discussion

[Bertho Boman <boman@vinland.com>]

It is not the length of wire that matters, it is whether or not there is current
flowing through the computer that counts.

In the case of large transients, there is no such thing as "ground".  The
Hot-Neutral-Ground line cord can have thousands of volts on it, so it is
important to understand that all that a transient suppresser really does is to
keep the voltage between the three wires to a reasonable value.

Maybe the easiest way to explain it is to use the example of "one hand in the
pocket" rule for electricians.  Basically, if you have good insulated rubber
shoes you can touch an electric wire with one hand as long as you do not touch
anything else. (the other had in the pocket). If the other hand touches ground
or neutral, there will be current flowing through the body and one might get
killed.

Having one protected point connecting to the computer where both power line and
phone wires are protected and connected to the common point is OK.  Connecting
two independent surge protectors allows current to flow through the "body" of
the computer.

By the way, this is also true for LAN cables, Cable TV and any other connection
of significant length that might have a ground connection somewhere else.
Bertho
======================

Bruce Roorda wrote:

> It seems that whether the phone surge arrestor is a separate box or in the
> same box as the power surge arrestor, the phone and power surge arrestors
> are different units.  Are you saying that the extra few feet of wire in the
> path to the house wiring ground makes a lot of difference?
>
> Bruce Roorda
> Possum Hill Farm


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