Excellent information on surges and surge protection is at:
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
- "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is a major organization of electrical and electronic engineers).
And also:
http://www.eeel.nist.gov/817/pubs/spd-anthology/files/Surges happen!.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001
The IEEE surge guide is more technical.
An adjacent protector will do one of two things. Either it will block a surge. Or it will absorb that surge energy.
Surge protectors do not work by "blocking" or "absorbing".
The IEEE surge guide explains (starting page 30) that plug-in protectors primarily work by limiting the voltage from each wire (power and signal) to the ground at the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment.
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All interconnected equipment needs to be connected to the same protector. External connections, like coax also must go through the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment.
How many joules in that protector? Well, its above zero. So they can call it 100% protection in advertising. But a destructive surge is hundreds of thousands of joules. How do near zero (hundreds of) joules in that protector absorb hundreds of thousands of joules? It doesn't.
Of course it doesn't.
The author of the NIST surge guide investigated how much energy might be absorbed in a MOV in a plug-in protector. Branch circuits were 10M and longer, and the surge on incoming power wires was up to 10,000A. (That is the maximum that has any reasonable probability of occurring, as below) The maximum energy at the MOV was a surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less. (This is based on wiring practice in the US and could vary with other wiring practices.)
Plug-in protectors with much higher ratings (like 960J) are readily available. High ratings mean long life. A plug-in protector, wired correctly, is very likely to protect from a very near very strong lightning strike.
It does not claim protection.
Complete nonsense.
Some protectors even have protected equipment warranties.
And both the IEEE and NIST surge guides say plug-in protectors are effective.
Earth one 'whole house' protector that costs about $1 per protected appliance.
Service panel protectors are a real good idea.
But from the NIST guide:
"Q - Will a surge protector installed at the service entrance be sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."
Service panel suppressors do not by themselves prevent high voltages from developing between power and phone/cable/... wires. The NIST surge guide suggests most equipment damage is from high voltage between power and signal wires.
More responsible companies sell the superior solution. Including Siemens, ABB, Keison, General Electric, Leviton, Square D, Clipsal, Ditek, Polyphaser, or Intermatic.
All these "responsible companies" except SquareD and Polyphaser make plug-in protectors and say they are effective. Westom says plug-in protectors don't work.
SquareD says for their "best" service panel suppressor "electronic equipment may need additional protection by installing plug-in [protectors] at the point of use."
Lightning is maybe 20,000 amps. So a minimal 'whole house' protector is 50,000 amps.
The author of the NIST surge guide looked at the surge current that could come in on residential power wires. The maximum with any reasonable probability of occurring was 10,000A per wire (30,000A for H-H-N). That is based on a 100,000A lighting strike to a utility pole adjacent to the house in typical urban overhead distribution.
Recommended ratings for service panel protectors is in the IEEE surge guide on page 18. Ratings far higher than 10,000A per wire mean the protector will have a long life.
Service panel protectors are very likely to protect anything connected only to power wires from a very near very strong lightning strike. They may or may not protect equipment connected to both power and signal wires
So thanks for your input as well.