Re: Lightning strike

In message <gemini.iitekv0067s8i00zs.spamhater@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Alan Wrigley <spamhater@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

> druck <news@xxxxxxxxxxxxxxxx> wrote:
>
> > On 28 Jun 2005 Alan Wrigley <spamhater@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
> > wrote:
> > > While I was away at the weekend the power lines at my house were struck by
> > > lightning and I've returned home to find my Risc PC doesn't work. It starts
> > > up and both hard drives spin up with the normal short-chug-chug as they are
> > > accessed. Then the computer just sits there with the hard drive light
> > > permanently on and there is no display at all.
> >
> > Is anything else in the house not working? A mains based spike would take out
> > quite a bit of equipment, but if the drives spin up, its unlikely to be that.
> > The most common damage is from lightening striks on phone lines which can
> > blow modemns and take out motherboards.
>
> OK, I have some more info now. Originally I was told by text message that the
> strike had blown my router so I assumed it had hit the phone line. When I got
> home I found that the router's DC adaptor wasn't working so I guessed that the
> strike had hit the power cables, connected a spare adaptor, power light came on
> and that seemed to confirm it. I'd already set up a spare router so didn't try
> the old one to see if it actually worked. Bad move... when my sister got home I
> got the full story and actually the connection lights on the router went out
> first, and the power light some time after. Also her caller display unit was
> damaged so obviously it was a phone line strike after all.

Nothing to say it can't be both. A recent strike on a church affected
systems in a school 100 yards away. It blew:

The UPS, the server downstream of the UPS, the router and two ethernet
switches connected to the router. It also affected equipment in the
telephone exchange. Normal service was resumed after a week.

This suggests either the surge came in on both mains and phone, or came in
on one and out on the other.

The UPS didn't protect the server, but I would not expect it to do that. If
it had been an online UPS, I might have hoped for some protection.

There are three categories of UPS - online, offline and near-line. Offline
runs your load from the mains except when it detects a problem.

Online runs the load from the invertor, drawing power from the battery, all
the time. When mains is present it is used to charge the battery. This type
of UPS does protect to a considerable degree against mains disturbance,
since there is no direct link between line in and line out. The earth is
common, and can pass on problems.

Offline UPSs don't offer protection against anything except failure of the
mains, and low voltage, "brown out", in some cases. Small UPSs sold for
single systems are all offline - it's a cheaper technology.

Near-line is a term used by some manufacturers to describe a UPS with some
characteristics of both types. Read the spec carefilly to find out exactly
what you're getting.

Alan

--
Alan Adams
alan.adams@xxxxxxxxxxxxxxxxxxxxxxxxxxx
http://www.nckc.org.uk/
.

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