QUOTE(kelv1983 @ Jan 7 2016, 12:35 PM)
The primary source of surges and spikes in most homes is appliances. When a large, motor-driven appliance shuts off (either manually, automatically, or due to AC power failure), energy stored in the motor coils can flow back down the power line, a phenomenon called inductive kick.
If that inductive kick exists, then it happens 120 times every second. Since AC power turns off (goes to zero) 120 times per second.
That inductive kick only exists in speculation. Include numbers. Any spike is noise - ie at most tens of volts. Protection already inside every appliance makes that noise irrelevant.
Anyone can know this. If motorized appliances are creating surges, then we are all trooping to stores daily to replace destroyed clocks, dimmer switches, smoke detectors, RCDs, recharging phones, etc. No such spike exists except where hearsay is misrepresented as fact.
Also irrelevant is a transient created by magnetic fields. That hearsay also only exists when numbers are ignored. And in direct contradiction to what is routinely observed. Surges are created by direct lightning strikes, linemen errors, stray cars, etc.
All appliances contain robust protection. Concern is a rare transient that can overwhelm that protection. As noted previously, these transients must be earthed BEFORE entering a building. These transients occur maybe once every seven years. Lightning is but one common example.
Effective protection means one can say where hundreds of thousands of joules are harmlessly absorbed. That means a surge connects low impedance (ie less than 3 meters, no sharp wire bends) to earth either directly (ie TV cable). Or a surge protector does what that hardwire does better.
An effective protector does not foolishly try to block or absorb a surge. An effective protector is a connecting device to what actually does protection - to what absorbs hundreds of thousands of joules - single point earth ground. As a connecting device, that protector must be rated at least 50,000 amps. Because a typical lightning strike might be 20,000 amps. Because protection means nobody even knew a surge existed. Because a protector must not fail - must not be damaged by a surge.
Protection is always about where hundreds of thousands of joules dissipate. A protector is only as effective as its earth ground.
This post has been edited by westom: Jan 8 2016, 11:40 PM