Re: Could a telephone line damage a modem ?
- From: "R. Mark Clayton" <nospamclayton@xxxxxxxxxxxxxx>
- Date: Mon, 3 Oct 2005 10:21:55 +0000 (UTC)
"w_tom" <w_tom1@xxxxxxxxxxx> wrote in message
news:434067DB.809F2E88@xxxxxxxxxxxxxx
> Electricity means a complete circuit. That means
> electricity must first have an incoming and outgoing path
> through each device in a circuit. Myths would have you
> believe a surge enters on phone line, damages a modem, then
> stops. Reality - first a transient forms a complete circuit
> through that modem. Only later does something in that circuit
> fail.
Well nearly right. A DC current needs a complete circuit. A transient -
e.g. induced by a nearby lightening strike, can shoot the voltage on the
cable up to thousands of volts. Some current will flow into the modem due
to internal and self capacitance. This may be enough to zap a modem.
> This is how transients damage modems AND how electronics
> damage is routinely avoided. BT has a £multi-million computer
> on their side of the same wire. That computer is connected to
> wires all over town. Why is that computer not damaged?
> Because they install what you don't have. They earth (shunt)
> all incoming lines through a 'whole house' protector.
Well when lightening hit a house about 250m away it zapped one of my phones
AND part of the local telephone exchange.
OTOH a good surge arrestor will reduce the likelihood of damage. It may be
worth having a look at the line with a scope - perhaps mains is leaking down
it or something.
SNIP
.
- References:
- Could a telephone line damage a modem ?
- From: jdr . smith
- Re: Could a telephone line damage a modem ?
- From: w_tom
- Could a telephone line damage a modem ?
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