Quote:
Originally Posted by flameout
One correction:
Surge protectors can absorb hundreds of joules... but redirect much more.
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If a 100 amp surge is incoming to the protector, then where is the outgoing path? The critically important term was low impedance (ie 'less than 10 feet', no sharp wire bends, etc). A 'whole house' protector has that. A completely different device adjacent to an appliance: where does that current go? Sometimes destructively to earth via any nearby appliance.
Once that current is inside, it will hunt for earth destructively via appliances. An adjacent protector can only do two things: 1) block that current or 2) absorb that energy. Many have observed appliance damage because an adjacent protector earthed that current destructively through nearby appliances.
Protector adjacent to an appliance can block what three miles of sky could not? Or somehow absorb hundreds of thousands of joules? Protection is always about where energy dissipates. Always.
What happens to a 100 amp surge at a protector and appliance? 50 feet of AC wire might be less than 0.2 ohms resistance to the breaker box. But the relevant term is repeated often: 'low impedance'. That same wire may be 120 ohms impedance. 100 amps times 120 ohms means a protector and appliance is at something less than 12,000 volts. Why would a surge find other paths to earth destructively via nearby appliances? 12,000 volts. Excessive impedance.
The adajcent protector can only block that current or absorb that energy. Otherwise it an only divert that surge detructively via appliances. Fortunately, most surges that destroy grossly undersized protectors are too tiny to harm adjacent appliances.
Low impedance is why a 'whole house' protector makes a 'less than 10 foot' connection to earth. No sharp wire bends. Ground wire not inside metallic conduit. Ground wire separated from all other wires. That ground connection - not the protector - is most important for protection.
That adjacent protector only says it will absorb how many joules? Where is any number for protection? Does not exist. They need you to believe it somehow stops or absorbs surges. Otherwise it can only divert that surge detructively into any nearby appliance. Only item that does protection - single point earth ground. Only effective protetors connect short to and can divert energy harmlessly to earth. Protection is always about where hundreds of thousands of joules dissipate. Always.