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Originally Posted by dar512
TW - What's the difference between the ground wire in your basic three prong plug and the earthing thing you talk about? If a house is wired correctly, the ground wire does eventually connect up to something stuck in the ground.
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Electricity is not same at both ends of a wire. Electricity appears somewhat same at both ends of a wire in some conditions. For human safety, ground on a wall receptacle is same as the safety ground inside a breaker box. But for transistor safety, both ends of this wire are not electrically same. The technical reason is wire impedance; not to be confused with wire resistance.
Destructive surges are not stopped, blocked, or absorbed - despite what plug-in protectors would appear to claim. As Franklin demonstrated, electrical transients must be shunted (redirected, diverted) to earth ground. For Franklin lightning rods, a connection to earth must be short, no splices, no sharp bends, not inside metallic conduit, etc.
Surge protector does same; shunts transients to earth. During a surge, a protector is but a wire. Connection from each AC electric wire to earth ground must be short, no splices, no sharp bends, etc. Protector makes that connection IF protector is properly earthed.
'Whole house' protectors are effective when connected less than 10 feet to earth ground. 'Whole house' protectors from responsible manufacturers such as Square D, Cutler-Hammer, Siemens, Intermatic, Leviton, and GE are installed at the service entrance. Earth ground wire from that mains breaker box to earth must be 'less than 10 feet', no spliced, no sharp bends, not inside conduit, and separated from non-earthing wires. Requirements that both meet and exceed post 1990 National Electrical Code (NEC) requirements.
Note manufacturer names specifically not mentioned: APC, Tripplite, Belkin. Products have no earth ground connection AND they avoid this discussion. Instead, they promote sound bytes and 'word association' as a replacement for good science and the all so critical earth ground.
Return to that equipment ground at a wall receptacle. That equipment ground wire is bundled with other non-earthing wires. It has numerous sharp bends. Too many splice. Far more than 10 feet from the earth ground rod. In short, a wall receptacle equipment ground, obviously, is not an earth ground. No earth ground means no effective protection.