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AC Power filter and phone line filter (homemade circuit breaker)

Discussion in 'Electronic Design' started by Emanuele, Oct 13, 2008.

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  1. Emanuele

    Emanuele Guest

  2. w_tom

    w_tom Guest

    Do you think that tiny circuit will stop what three miles of sky
    could not?

    Where does that surge energy go? Does this circuit stop or absorb
    that energy?

    Notice the ground wire simply carries the surge completely around
    the circuit. And other components divert that surge energy into the
    ground wire where it connects directly to the appliance on right side

    Most of what would work in this circuit is already inside every
    appliance. Internal appliance protection assumes that surge energy
    gets earthed before entering the buillding. Again, where does that
    massive energy get dissiipated? In this circuit? In the appliance?
    Of course not.

    Destructive surges seek earth ground. Once permitted inside a
    building, destructive paths to earth may be everywhere. Protection
    means the surge is given earth BEFORE entering a building.

    Protection means massive surge energy gets absorbed and dissipated
    harmlessly in earth. IOW any wire that would carry a surge into the
    house must first be earthed where it enters the building.

    Did you know all telco lines already have a 'whole house' protector
    installed for free? What actually provides protection? Not that
    protector. Telco 'installed for free' protector is so effective when
    connecting each wire in that cable to earth ground - ie 'less than 10
    feet' to earth. Where is surge energy harmlessly dissipated? In
    earth and before that surge can enter a building.

    Whereas cable and telephone have protection installed for free, AC
    electric does not. So that protection already inside all appliances
    is not overwhelmed, install (and properly earth) one 'whole house'
    protector. See GE, Siemens, Square D, Kieson, Cutler-Hammer,
    Intermatic, Levition, et al for effective solutions. No such
    solutions are sold by APC, Belkin, Tripplite, Monster Cable, etc.
    Some sources:

    See that wire that is not drawn as a wire? It connects a surge on
    any incoming wire to directly to the 'protected' appliance. Just one
    reason why such circuits can sometimes provide surges with even more
    destructive paths around protection inside the appliance. Instead
    earth the surge before it even enters a building.
  3. JosephKK

    JosephKK Guest

    The electric mains most certainly do in the US and Canada.
  4. Guest

    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:
    And one from the US-NIST at:

    The IEEE guide is aimed at people with some technical background. The
    NIST guide is aimed at the unwashed masses.
    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.
    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.
    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.
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