From: "Charles Perry"
Subject: Re: Interference from power lines
Date: Mon, 6 Jan 2003 09:55:39 -0500
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"DarkMatter" wrote in message
> On Mon, 06 Jan 2003 08:40:56 GMT, "Pacific Freight"
> Gave us:
> >I assume that the computers are networked? Might be an idea to disconnect
> >any network cables between computers while you are doing your testing. I
> >think that the network cables have a common ground pin which might
> >complicate matters. If someone has made a mistake in temporarily rewiring
> >your premises, (especially with neutral) there may be high potentials
> >between computers plugged into different circuits or phases. Then
> >your test with the isolated UPS supply and let us know.
> I don't think that the inputs to a NIC are grounded. In fact, I
> think they are quite isolated. Both at the NIC, and at the HUBs,
> switches and router in which they are attached.
Actually you can get into potential (the voltage kind) problems across
networks. We have investigated several cases where improper grounding and
improperly applied surge protectors have caused data errors and even
hardware failure. They make a surge protectors that includes plugs for
network, telephone, etc, as well as power. These equalize the potential of
these networks during a surge.
Charles Perry P.E.