Surge Protectors

[dennis]

Clamping to what?

[Bud--]

?Grounding? in the following is ?earthing? in the UK. It is not obvious to me what the syntax is using earthing. Earthing as used in posts by w_ and me usually indicates a connection to the dirt/earth.

?Clamping? is to the common ground at the plug-in suppressor. For a TV with cable connection, both power and cable need to go through the suppressor. The cable shield connects to the power ?earthing? wire at the suppressor and the voltage on other wires is clamped to that point.

An illustration in the IEEE guide, starting pdf page 40, shows a lightning induced surge hitting cable TV supply wiring. The surge current lifts the cable TV ground reference away from the power ground reference so cable TV leads are 10,000V different from the power. This shows up at any TV connected to power and a cable lead, and the TV won?t like it. A plug?in suppressor clamps the voltage on both the cable and power wires to the ground reference at the suppressor. The voltages reaching the TV are at a safe voltage.

According to the NIST guide, US insurance information indicates equipment most frequently damaged by lightning is computers with a modem connection, TVs and video recorders (presumably with cable TV connections). All can be damaged by voltages between power and signal ground references.

-- bud--

[Andrew Gabriel]

Oh, don't forget the _aluminum_ wiring, wirenuts, ...

Whereas we use wood and aluminium to make fireworks, and along with most of the rest of the world, banned Screwits about 60 years ago, although strangely they do look a bit like exposives fuses;-)

[Bob Eager]

(yawn)

They do in the UK.

(boring stuff snipped)

Yawn.

[tony sayer]

And all dependant on the earth they are in turn connected to!..

Perhaps you don't understand ?. We see this on the telecoms sites and transmitter sites we look after and he's correct on the principles involved....

[Huge]

Well, yes, but we were talking about lightning.

(I was in Rochester, NY, one summer and the thunderstorms were like nothing I'd ever seen before, or since. I could stand on the balcony of my hotel room and see about 7 or 8 collosal thunderstorms. And this happened every evening!)

When I replaced my mother's garbage disposal (she lives in Pennsylvania) I initially wondered what they were...