On Aug 13, 5:31 pm, (Al Dykes) wrote:
In large buildings where all the utility wire is below-ground, it
might be nothing. In surburbia with above-ground power, I'd put a
whole-house protector in the panel and a "better" powerstrip under
each PC.

A breaker box 'whole house' protector (www.smarthome.com) has an
earthing wire. Therefore it has an earth ground to shunt (connect,
divert, clamp) surges. Nobody says that protector stops, blocks, or
absorbs surges. But your post implies that myth. How does a one inch
part inside a protector stop surges that could not be stopped by three
miles of sky? No protector stops or absorbs destructive surges.
Otherwise even galvanic isolation inside all appliances would make all
surges irrelevant.

A surge that overwhelms the many appliance protection circuits
(galvanic isolation is only one and is also installed for human
safety) cannot be stopped and cannot be absorbed. Destructive surge
seeks earth ground. Either it is earthed via a wire (cable TV,
satellite dish) or is earthed via a protector (AC electric,
telephone). The smarthome.com protector with a dedicated earthing
connection does earthing.

What doe MOVs do? Well since we cannot make a wire connection to
earth, then MOVs make that wire connection only during surges. How
good is that connection? Increased joules is same as increased wire
gauge. Joules do not define protection. Joules is the ballpark
number for potector life epectancy.

Why do some protectors fail during a surge - as the indicator light
reports? Those protectors are grossly undersized. Grossly
undersizing gets the naive to recommend more ineffective protectors.
The effective 'whole house' protector is sufficiently sized (has
enough joules) as to earth direct lightning strikes. A human never
even knows a surge existed when using minimally sufficient
protectors. Sufficiently sized does not promote protectors among the
naive. But that is what the effective protector does - conduct to
earth and remain functional.

Makes no difference whether incoming wire is overhead or
underground. Every wire in every cable that enters the building must
connect to same earthing electrode - either directly or via a
protector. This figure from an industry professional demonstrates
same principles for two structures. Each structure has its own single
point earth ground. Underground wire to the building also carries
surges:
http://www.erico.com/public/library/...es/tncr002.pdf

Another industry professional also demonstrates why underground
wires entering a building without earthing can cause damage:
http://tinyurl.com/38v2dv
Lightning strikes somewhere across the street close to the below
grade West cable vault. ... The first line of defense is the telco
protection panel, but the panel must be connected to a low
resistance / inductance ground. There was no adequate ground
available in the telephone room.

MOVs are simply one type of connecting device to earth ground.
Others include 3mill carbons, avalanche diodes, gas discharge tubes,
etc. In each case, the protector is only a connecting device - shunts
(clamps, connects, diverts, conducts) a surge to what the surge wants
- earth ground.

Never assume a protector is protection. That is science based in
word association. A 'protector' is a connecting device to
protection. 'Protection' (via a protector or just using a wire) is
earth ground.

Meanwhile, plug-in protector does not even have an earthing
connection. Therefore its manufacturer avoids discussing earthing.
Primary objective of plug-in protectors - profits. No wonder Monster
Cable sells a $100+ protector that is same as the $10 protector in the
grocery store.