View Single Post
  #223   Report Post  
Posted to alt.comp.hardware.pc-homebuilt,alt.home.repair,alt.engineering.electrical,alt.tv.tech.hdtv,sci.electronics.basics
Bud-- Bud-- is offline
external usenet poster
 
Posts: 1,981
Default Surge / Ground / Lightning

Mike Tomlinson wrote:
In article , bud--
writes

Phone wires were clamped to ground before the 1960s?


It was common to earth one leg of the incoming pair to either the house
ground or to its own rod. An earth connection also allowed "party
lines", where two houses could share one physical phone line pair, each
house with its own number. Disadvantage was that both lines could not
be used simultaneously.

http://en.wikipedia.org/wiki/Party_line_(telephony)

My previous house still had its telephone earth rod and earth wire,
though it had not been connected to the phone line for many years.


I am pretty sure we had a party line long ago when I was a kid.
Wikipedia's reference to "20th century telephone systems" makes me feel
even older.
One side of the ringer is all that was connected to earth.

Not clamping phone wires to earth is a major surge suppression flaw. It
allows high voltage from phone to power wires (like at a modem), and
increases the stress on a multiport plug-in suppressor. A service panel
suppressor doesn't help the voltage difference at all.

Surprising since the UK seems to be very good on electrical protection
in general.

--
bud--