On Monday 08 December 2003 18:08, Chris Walker wrote:

There's a company local to Norwich called Grey Electronics that sell modem protectors. I have one around here somewhere but I've been a bit lax in not buying one to protect my ADSL router.

Reject any type that doesn't filter mains as well. (or at least have a decent earth connection)

Why ?

Erm umpteen zillion volt lightening bolt (or just a transient induced voltage) will need to be going to ground. unless filter is the size of a house, or has a decent earth it won't work !

I've seen modem filters that are just a box that goes in the line, unlikely to do very much as your modem and computer will still be a far more attractive path to ground.

Oh and also reject any line filter that doesn't say it can cope with ADSL (if that's what you have) Some of them are a bit of a bandpass filter as well and that will upset ADSL unless the filter has been designed to let it through.

Most modem deaths are an induced voltage picked up by the line from a near strike, more often happens in the sticks where a higher percentage of lines are in the air. If you get a direct strike, you will be lucky to find your modem, let alone use it again.

Never really understood why BT don't just put a smallish spark gap at the point the line enters the house, tie it to a convenient ground. Won't stop the transients, but would stop the "Ok so who replaced all my phones with charred lumps of plastic during the lightning storm last night" That I saw a few times when I used to fill out technical insurance reports at a previous job.