In reply to a post by Brunel:

If the 'phone line receives a direct hit from a lightening strike, nothing will protect it and anything connected.

Exactly. Direct lighting strikes do not damage telephone switching centers, munitions dumps, broadcasting stations, and even occupants in cars. Protection has always been about a current's path to earth. Voltage is near zero IF that connection is properly installed.

Voltage only exists when one foolishly tries to 'block' that current. A solution originally demonstrated to all (without numbers) in elementary school science. Properly earthed 'whole house' protection means direct lightning strikes without damage. Because properly installed protection means massive current with near zero voltage.

Damage is only created when one foolishly ignores simple science. Anyone who cannot understand layman science should stop reading now.

Lightning seeks earth ground. A 20,000 amp electric surge is via a wooden church steeple destructively to earth. Wood is not a good conductor. So 20,000 amps creates a high voltage. 20,000 amps times a high voltage is high energy. Church steeple damaged.

Franklin installed a lightning rod. Now 20,000 amps is via a wire to an earthing electrode. Then high current creates near zero voltage. 20,000 amps times a near zero voltage is near zero energy. Structure undamaged.

Lightning seeks earth ground. A lightning strike to utility wires far down the street is a direct strike, incoming to every household appliance, destructively to earth. Appliances are not a good conductor. So lightning creates a high voltage. Lightning current times a high voltage is high energy. Appliances damaged.

For over 100 years, facilities that cannot have damage installed superior earthing connected low impedance (ie less than 10 feet) via a 'whole house' protector to an earthing electrode. Then high current creates near zero voltage. 20,000 amps times a near zero voltage is near zero energy. Appliances undamaged.

High voltage only exists when something adjacent to an appliance tries to 'block' or 'absorb' that energy. Anyone can read numbers. Those magic box protectors claim to 'absorb' hundreds of joules. Near zero energy. Destructive surges are hundreds of thousands of joules. When something completely different (called a surge protector) connects low impedance (ie wire without any sharp bends) to earth, then a protector absorbs near zero energy, hundreds of thousands of joules dissipate harmlessly in earth, and high voltages do not exist. A direct lightning strike without damage by doing what Franklin demonstrated some 260 years ago.

Protectors throughout the world are properly earthed so that direct lightning strikes need not create a high voltage; need not damage anything connected to a phone wire. Well understood even 100 yeas ago; demonstrated by Franklin some 260 years ago. Introduced to all in elementary school science. And unknown to many who somehow know otherwise.

Hysterical V=IR actually.

Ohm I god.

Edited by Deadbeat (Sun 21-Feb-16 18:19:37)

In reply to a post by BatBoy:

V=IR actually.

One who learns a soundbyte without experience will never learn what V=IR means.

A 230 volt 100 watt light bulb measures about 40 ohms. Using those numbers, explain why your equation does not work. Nothing wrong with those numbers. Nothing wrong with the equation. More than a soundbyte is required to understand simple things such as how a high current creates a tiny voltage when simple and effective protection is installed.

Little hint not found in sounbytes. R is not a constant.

High voltage only exists when something adjacent to an appliance tries to 'block' or 'absorb' that energy.

Here is a thing that I don't know what you're on about

In reply to a post by westom:

In reply to a post by smiffy12:

I kid you not, the small, white, rectangular box on the window sill that changes the external BT cable to internal type blew up and became a smouldering lump of blackened plastic with shards of it exploding across the room.

Lightning typically does not do damage as you observed. That typically occurs due to something called a follow-through current. Where lightning damage creates an electrical connection to something with much larger power.

Can you explain what this "something" is?

American?

In reply to a post by BatBoy:

Can you explain what this "something" is?

I could. But you clearly do not even understand V=IR. Numbers were provided so that you can first learn this simple stuff. If you cannot / do not explain your mistake, then further explanation is too complex for you.

Edited by deleted (Tue 23-Feb-16 15:53:59)

In reply to a post by westom:

In reply to a post by BatBoy:

Can you explain what this "something" is?

I could.

Go on then, I'm waiting...

Ohms law.
More specifically, Ohm's law states that the R in this relation is constant, independent of the current.

In reply to a post by broadband66:

Ohms law.
More specifically, Ohm's law states assumes that the R in this relation is constant, independent of the current.

Allow me to correct that for you.