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It is not like a circuit breaker. It is a surge suppressor.
You have not described your interest - what you want to protect.
If MOVs on power circuits are hit repetitively hit with large surges
they will deteriorate and eventually can fail. The failure can lead to
a fire. Commercial surge suppressors in the US are covered by UL
standards. Part of the UL standard is that overheating MOVs be removed
from the circuit. The device shown does not have that protection.
Years ago I had a homemade surge suppressor which I stopped using
because it lacked that protection. I assume standards in other
countries require equivalent protection.
I would strongly advise against any device like this that is not UL
listed (or the equivalent for other countries). The UL standard
includes a lot more than just disconnecting MOVs.
Excellent information on surges and surge protection is in an IEEE
guide at:
<
http://www.mikeholt.com/files/PDF/
LightningGuide_FINALpublishedversion_May051.pdf>
And one from the US-NIST at:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
The IEEE guide is aimed at people with some technical background. The
NIST guide is aimed at the unwashed masses.
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Where does that surge energy go? Does this circuit stop or absorb
that energy?
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Poor w_ can't figure out how plug-in suppressors work. It is explained
in the IEEE guide - they work by CLAMPING (limiting) the voltage on
all wires (signal and power) to the common ground at the suppressor.
Plug-in suppressors do not work primarily by earthing (or stopping or
absorbing). The guide explains earthing occurs elsewhere. (Read the
guide starting pdf page 40).
Note that all interconnected equipment needs to be connected to the
same plug-in suppressor, or interconnecting wires need to go through
the suppressor. External connections, like phone, also need to go
through the suppressor. Connecting all wiring through the suppressor
prevents damaging voltages between power and signal wires. These
multiport suppressors are described in both guides.
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Where is surge energy harmlessly dissipated? In
earth and before that surge can enter a building.
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w_ has a religious belief (immune from challenge) that surge
protection must use earthing. Thus in his view plug-in suppressors
(which are not well earthed) can not possibly work. w_'s religious
blinders do not allow him to read the explanation in the IEEE guide.
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install (and properly earth) one 'whole house'
protector. See GE, Siemens, Square D, Kieson, Cutler-Hammer,
Intermatic, Levition, et al for effective solutions.
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Service panel suppressors are a good idea.
What does the NIST guide say?
"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 limit the voltage between power and
phone/cable wires. The major cause of damage to equipment is probably
high voltage between power and signal wires (see the example in the
IEEE guide starting pdf page 40).
All w_’s manufacturers except SquareD make plug-in suppressors.
For it’s “best” service panel suppressor SquareD says "electronic
equipment may need additional protection by installing plug-in [surge
suppressor] devices at the point of use."
For real science read the IEEE and NIST guides. Both say plug-in
suppressors are effective.
