Whole house surge suppressors

Discussion in 'A+ Certification' started by Flea Ridden, Jul 5, 2004.

  1. Flea Ridden

    w_tom Guest

    A nail pounded into the floor and labeled 'ground' would be
    effective if destructive surges were normal mode. But
    destructive surges are not same as what plug-in protectors
    claim to protect from. For protection from the typically
    destructive surge, that single point earth ground is
    essential. One need not even have a surge protector to have
    effective protection. But a single point earth ground is
    always essential to that protection.

    We earth for two reasons. One is to dump a transient into
    earth using a most conductive path into earth. A nail into
    the floor with a sign that said 'ground' would simply violate
    the principle. However if you have a problem with this, then
    please feel free to cite an IEEE or equivalent source that
    demonstrates how a floor nail constitutes a conductive earth
    ground.

    Wires alone need not violate the single point ground
    principle to permit surge damage. When discussing surges,
    then concrete, linoleum tile, baseboard heat, and some wall
    paints would violate your 'single point nail ground'
    principle. A building is full of materials and construction
    techniques that can violate the single point ground. A
    concept made so difficult inside the typical building that
    earthing is performed for the entire building - to keep it
    simple. It is possible to earth sections of a building as is
    performed in skyscrapers - ie Empire State Building. But for
    a protection system to be effective, that single point
    conductive connection to earth must always exist.
     
    w_tom, Jul 12, 2004
    #61
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  2. Flea Ridden

    Chris Lewis Guest

    You continue to parrot the same nonsense without any understanding
    whatsoever.

    A nail pounded into the floor is perfectly effective as a "ground"
    to protect a device as long as every conductor entering a device is
    overvoltage-clamped relative to it.

    Surges cause damage to equipment when there are large voltage
    differences between the conductors entering a device. If the
    conductors are all clamped (via MOVs or whatever) to stay within
    bounds of each other, it doesn't matter if the whole assembly is
    lifted 1000's of volts away from "real" ground.

    Good quality "point suppressors" do exactly that - 3 MOVs clamping
    all three conductors in a circuit.

    This is obvious with aircraft especially helicopters where an
    "effective earth ground" is obviously not possible. If whole-house
    surge suppressors attached to good grounds were the only thing
    that was going to work, then aircraft wouldn't survive lightning
    strikes. But they do.

    Helicopters generate static charges sufficiently energetic to knock
    people off their feet. Does it scramble their electronics? No.
    Because they have point overvoltage protection on everything.

    Lightning strikes act just like nuclear EMP. Just not nearly
    as energetic. Within a radius of a lightning strike, there are
    high speed transients induced on _everything_, grounded or not.
    Proper close-in point-protection on a piece of equipment is going
    to work better than a whole house suppressor on the other side
    of the house no matter how well grounded the whole house suppressor is.

    [Short of blowing the MOVs]
     
    Chris Lewis, Jul 12, 2004
    #62
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  3. Flea Ridden

    Chris Lewis Guest

    A small van der graf generator producing a wimpy 50Kv can light
    up fluorescent bulbs within a few feet. That sort of voltage
    difference (at least 60-70 volts with enough current to produce
    visible light) is ample to destroy electronics (ie: punch a hole
    through a MOS gate).

    A lightning strike is many orders of magnitude higher voltage
    and even more orders of magnitude more current than that.

    Heck, we've had people in alt.home.repair measure 60v on a disconnected
    conductor in a length of house wire using a sensitive enough DVM.

    Go read up on transformers some time.
     
    Chris Lewis, Jul 12, 2004
    #63
  4. Flea Ridden

    Chet Hayes Guest




    I see Tom is at it again with the usual wandering posts, more like
    ranting and raving actually, on his favorite topic. The common theme
    is:

    1 - All you need is whole house entrance protection

    2 - If anything gets damaged by lightening with that in place, well
    it's "human failure", eg you must have done something wrong.

    3 - Using plug in surge protectors, either as additional protection,
    or for those living in say rental properties or apartments, only makes
    things worse and leads to damage.

    4 - If anyone reports having seen several pieces of eqpt that were
    protected with a plug in protector escape damage, while another
    unprotected piece got zapped, that's just dismissed, since he knows
    better.

    5 - If anyone sees a piece of eqpt with lightening damage on a comm
    port, or a telephone line, well, Tom knows lightening so well and it's
    so predictable, that the surge came in on the AC service entrance,
    went through the whole house, and then chose to exit on the comm or
    telephone line on the way out. He knows that's how my Tivo got it,
    not from a lightening surge on the phone line.


    The best part is how he continues to challenge people like Sparky to
    provide scientific data, yet ignores it when they do and never
    provides any himself. So, Tom, here it is again for you, straight
    from the National Lightning Safety Institute. They clearly discuss
    both direct and INDUCED EFFECTS caused by lightning, complete with
    discussions of field strength, induced currents, etc. Perhaps it will
    actually sink in this time, but I doubt it.

    http://www.lightningsafety.com/nlsi_lhm/effect.html
     
    Chet Hayes, Jul 12, 2004
    #64
  5. Flea Ridden

    chris Guest

    Hi

    Maybe we should remove this thread from the A+ newsgroup. Although somewhat
    interesting it is really not related to A+. You should start your own group,
    Lightning and its effects.

    Chris
     
    chris, Jul 12, 2004
    #65
  6. Flea Ridden

    zxcvbob Guest

    [snip]

    The repairman (a different guy than last week) came out this morning and
    said he talked to his supervisor and it's the customer's responsibility
    to ground the NID (!) I pointed out that the ground connection is
    inside the telco half of the box and customers don't have access to the
    ground terminal. He said if the customer has a ground wire sticking out
    of the wall when they install the NID they hook it up, otherwise they
    leave it disconnected. He said the phone cable is low-voltage so the
    national electric code doesn't apply -- the NFPA *thinks* it applies,
    but Qwest has a lawsuit or something where they are challenging it.
    Sounds like bullshit to me.

    I didn't argue with the guy; I asked him if he could unscrew the box so
    I could attach an earth wire without having to cut the box open. He
    unscrewed the fancy-headed locking screw and showed me where to attach
    the wire and to make sure I tighten the customer-side screw when I was
    done to keep the weather out. I have a 1000' roll of #12 green wire
    that I'll never use up, and I've fished the end of it through the siding
    and exterior wall already. It'll take me less than 15 minutes to finish
    the job this evening.

    Next time I see my friend who's a supervisor at the city's building
    safety office I think I'll mention this and see what he says. It's
    disturbing that Qwest's policy is to install aerial phone lines without
    earthing them at all. And I assume they only connect buried cable's
    metal shield to the ground block and don't connect it to the building's
    ground electrode system.

    Best regards,
    Bob
     
    zxcvbob, Jul 12, 2004
    #66
  7. I have seen a horizontal yoke on a 27" TV arcing, which took out the
    mainboard in the shop PC (8 or so feet away), and temporarily
    scrambled the LED display on the Sencore oscilloscope nearby,
    requiring it to be reset. A lightning strike would have much more
    energy than that.

    Tom
     
    Tom MacIntyre, Jul 12, 2004
    #67
  8. Well, the first post was here, it's been here from the start, but it
    appears that I am the only regular here who has been posting to the
    thread.

    Tom
     
    Tom MacIntyre, Jul 12, 2004
    #68
  9. There's an A+ question right there. I think the accepted answer is 30
    volts.

    Tom
     
    Tom MacIntyre, Jul 12, 2004
    #69
  10. Flea Ridden

    AG Guest

    [snip]
    I had been hoping that this thread would die but DAMN that is STUPID. There
    is a Telco ground at the pole on every one where their service comes off to
    the house. I know I just about broke a lawnmower blade on one a few years
    ago.
    These guys are asking for a law suite when someone is killed by a lightning
    strike and their on the phone.
    AG
     
    AG, Jul 12, 2004
    #70
  11. Flea Ridden

    Chip Orange Guest

    File a complaint with your state's public utilities commission.
     
    Chip Orange, Jul 13, 2004
    #71
  12. Flea Ridden

    Bonehenge Guest

    That ground is not connected to anyone's phone. Both conductors of a
    POTS line are wired all the way back to a ground at the central office
    or the closest piece of loop electronics, A.K.A "SLC". Grounds on
    poles are for repeater cases, terminal cases, CATV, or the electric
    company. Many times, they aren't grounds at all, but guy wires
    supporting the pole.
    The phone co. side of the NID needs to be grounded for the lightning
    protectors inside the NID to work. These devices shunt overvoltages
    to ground, and open if an overcurrent condition exists. There is
    similar equippage at the other end of the wire, where it connects to
    the central office or loop electronics. The customer side of the NID
    needs no lightning protection, as that side is past the point where
    lightning would enter the premise. A lightning strike along the wire
    would invoke the protection, which usually leaves the line either open
    or grounded, until a repair person replaces the protector(s).

    Be careful mowing the lawn.

    Barry
     
    Bonehenge, Jul 13, 2004
    #72
  13. Flea Ridden

    w_tom Guest

    From the FCC Part 68 Connection of Terminal Equipment to
    the Telephone Network:
     
    w_tom, Jul 13, 2004
    #73
  14. Flea Ridden

    w_tom Guest

    So lightning enters the building on AC electric (black hot
    wire) seeking earth ground. It arrives at those three MOVs
    (called a plug-in surge protector) adjacent to a computer.
    Now where does lightning go. Through an MOV to a spike in the
    floor? That spike is not well connected to earth. Instead,
    those MOVs shunt (distribute) that lightning strike to all AC
    electric wires. More wires to seek earth ground,
    destructively, through the adjacent computer.

    Some possible paths from computer to earth ground - phone
    line through modem; serial port cable where it drapes over
    baseboard heat; or out via network card. These are all
    potentially computer destructive paths because 1) a superior
    and single point earth ground was not utilized at the service
    entrance ('whole house' protector) and 2) because the spike in
    a floor only labeled as ground does not make a conductive
    connection to earth.

    Chris Lewis's assumptions might be valid for normal mode
    protection. And that is what Chris Lewis has assumed all
    surges are:
    But just like the plug-in protector manufacturers, Chris
    forgets that typically destructive surges are common mode.
    That means no voltage difference between wires while a
    destructive voltage difference exists between ALL wires and
    earth ground.
    Therefore the 'spike labeled ground' accomplishes nothing
    and leaves electronics exposed to destructive transients.

    Aircraft grounding is completely different and more
    complex. If one does not even understand normal and
    longitudinal transients, then one has no right trying to
    complicate the concepts by discussing aircraft. We are
    discussing terrestrial structures and destructive transients.
    Any discussion about aircraft only confuses the issue made
    complicated enough when Chris does not even understand the
    transient that is typically destructive. Instead he assumes a
    transient is only a voltage between two wires. There are
    other and typically more destructive types of transients. And
    no place are we discussing helicopters.
     
    w_tom, Jul 13, 2004
    #74
  15. Flea Ridden

    Chris Lewis Guest

    No, silly. Thru the ground wire to the ground.
    If you had bothered to _read_ my posting, you would have seen
    I said "the conductors entering a device". Last I heard,
    phone lines, and network cables were "conductors".
    That superior and single point earth ground _was_ utilized. It
    just doesn't necessarily have a "whole house" protector on it.
    You're not paying attention. "conductors entering a device"
    means _all_ of them. Including the ground wire (if any).
    It doesn't matter. If none of the conductors entering
    a device have destructive voltage differences, there is
    no danger.
     
    Chris Lewis, Jul 14, 2004
    #75
  16. Flea Ridden

    w_tom Guest

    The assumption: a nail pounded in the floor that is a good
    earth conductor, and all incoming conductor first connecting
    to that nail. This system work assuming the building was
    constructed to make that room a 'building within the
    building'. Same technique is used in skyscrapers to make all
    electronics on one floor protected. But the nail into a
    wooden floor or a nail only inches into a concrete floor is
    not sufficient protection. Good luck trying to retrofit that
    room after the building is constructed. Yes, it can be
    accomplished. Yes that nail firmly attached to a conductive
    earth ground can also become the third layer of protection
    (after primary utility and secondary 'whole house'
    protection). But notice the numerous special considerations
    that are required to make that system effective. Once we
    apply reality, then a nail is not a good earth ground and not
    everything entering the room can first connect to that nail.
    Have you included the wall paint in your list of conductors?
    That too must connect to the nail.

    In my post, even the serial port cable from computer to
    'nail' can easily compromise a protection system via a
    conductor that is not connected to the nail - ie baseboard
    heat. This complexity is why we, instead, install a simpler
    protection system - the 'whole house' system with a short
    distance to the superior earthing conductor and wire
    separation to the electronics. That wire separation (between
    room and central earth ground) becomes part of the protection
    system that is simpler to install and more reliable.

    In short, the 'nail in the floor' protection system is
    subject to potential weaknesses made unnecessary by a 'whole
    house' system and a superior building wide earthing system.
    It can be accomplished, but only if additional complications
    are first addressed.

    The nail must not just be the center point junction. It
    must also be the best conductor to earth ground in that room.
    That made necessary by the compromises created by building
    materials and standard construction practices.

    Not only must the nail in the floor system be carefully
    implemented, but the far less expensive 'whole house'
    protector system and existing protection inside appliances
    makes that nail redundant - an unnecessary expense.
     
    w_tom, Jul 16, 2004
    #76
  17. Flea Ridden

    zxcvbob Guest


    I wrote to the local electrical inspector, explained the whole thing
    (with a full orchestration and 5-part harmony and stuff like that) and
    told him I was contacting him first because FCC Part 68 "Connection of
    Terminal Equipment to the Telephone Network" gave him jurisdiction, and
    this seemed like a dangerous public safety issue he needed to be aware
    of. Here's his response:
    Maybe I should have included the "27 8x10 color glossy photographs, with
    circles and arrows, and a paragraph on the back of each one, explaining
    what each one was to be used as evidence..." (it's kind of scary that I
    can quote old Arlo Guthrie material from memory)

    Best regards,
    Bob
     
    zxcvbob, Jul 16, 2004
    #77
  18. The presence of the ground lug indicates that some type of arrester is
    involved, even if it's just a gap. See
    http://www.taunton.com/finehomebuilding/pdf/Lightning.pdf

    He is right that his department and the NEC doesn't apply to utilities. The
    code in question is the NESC, and among its requirements is one stating that
    arresters that require grounding be grounded, and another stating that
    accessible communication equipment subject to overvoltage be protected
    against overvoltage.
     
    Steve Alexanderson, Jul 16, 2004
    #78
  19. As far as I know, that is *absolutely* correct.
    It does in fact have some form of surge protection.

    That is not strictly true, though it nearly is. It does *not*
    protect "the wire sheathing" in any case. It is true that it is
    there to protect the telco equipment, and if that happens to
    accidentally protect the customer's equipment, it is indeed just
    and accident. The problem for the customer is that virtually
    anything, other than a relatively old telephone, normally
    connected to the line is going to be *much* more sensitive to
    surges than the telco's equipment.

    Which is to say the telco is not providing protection adequate
    for modern customer equipment.

    That is not true. There is often *no* protection, other than
    properly grounding the cable sheath, at the point where the drop
    is connected to the cable. That is more likely to be true with
    aerial drops than with buried cable.
    Yep (several times over, as all of that is true).

    Ack! You must be a commie!
     
    Floyd L. Davidson, Jul 16, 2004
    #79
  20. Flea Ridden

    Chris Lewis Guest

    Stop there.

    I've come to the conclusion that you're a computer program, generating
    randomly perturbed iterations of the same misrepresentation at random times.

    Noone has claimed that a nail pounded into the floor is a good earth
    conductor.

    Just that if all of the conductors into a device are OVP'd to a single
    point, whether it be a real ground, a nail pounded into the floor (or
    your head), or a wire splice in mid-air, protects that device from
    voltage spikes.

    Indeed, given standing wave effects, inductive/capacitive pickup,
    and a whole host of other RF considerations, the _closer_ the OVP is
    to the protected device, the better. It's called "minimizing the
    effective antenna".

    Or do I have to tell you the story about how moving the OVP 4 inches
    along a conductor made all the difference between a microprocessor
    fry and non-fry? Be careful what you wish for...
     
    Chris Lewis, Jul 16, 2004
    #80
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