Telephone Surge Protection

Hi James,

A short terminology. Usually the term 'surge' is ment to describe high energy-short time pulses as we can see in lightning strike on telecom lines. If you want to protect your equipment only from 220volt condition then this is called as 'AC power fault' condition.

For those purposes there are special fuses (telelink series from Littlefuse- formaly Teccor, for example) that are designed to pass the surge pulses (that other devices are protecting from - SIDACTORS), but protects your equipment from the longer periods of AC voltage like the 220 volt. These fuses don't need any grounds because they are in series to the line itself. (The sidactors may need some ground connection - depending on your application).

you can see some examples here:

http://www.littelfuse.com/data/en/Application_Notes/3Analog.pdf

Good Luck, Tamir.

My dear do mean a leakage from power-line on your telephone lines/system or through your equipment leakage to your communication circuits?

Reply from "tamirb"is enough to differentiate between 'Surge' & 'Leakage'.

Inold days all when aerial lines were used the tele-lines were protected from crossing overhead powerlines by having a wire mesh between both & grounded.

But now most are under-ground the only threat remains by bad planning of under-ground cables of leakage between poer & phone cables, which should be looked into by both the authorities.

Can you clear your exact problem?

Yes i want such ciruit ,if 220 ac power suppy direct applied to tell phone line.than this circuit prevent form damage to phone or other telecom devices.

I google but all circuits needs earth connection.But i want such circuit that have NO earth concept.