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Is My Lamp Grounded?

Discussion in 'Electrical Engineering' started by Omar Elschatti, Sep 26, 2003.

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  1. Hi,

    how can I easily test if my metal-lamp is properly grounded?

    Thanks for every help,
  2. Greg-EE

    Greg-EE Guest

    Do a contuinty test from ground to the lamp while it is plugged in.
  3. Zathera

    Zathera Guest

    2 pronged plug? not grounded, 3 prong plug maybe. With the lamp
    disconnected use an ohm meter from each conductor to the frame. This will at
    least tell you if it isolated. If there are 3 wires then one will read

    My uncle had a house north of Paris, FR. All the lighting was 220v there was
    a metal parlor lamp that with bare feet, and touching it shocked me. Uncle's
    solution was to wear slippers and place the lamp on a rug.
  4. Louis Bybee

    Louis Bybee Guest

    A contuinity test will indicate if there is contuinity between two points.
    If the grounding conductor is damaged, or frayed, at any point, it could
    leave a situation where just one small strand of a 16 ga., or smaller (lamp
    fixture), wire is still connected, and such a test would indicate contuinity
    leaving you to believe all is well. If the integrity of the grounding path
    is important to you an additional test under load should be conducted.

    Remove the fish in address to respond
  5. DarkMatter

    DarkMatter Guest

    But it MUST be a PHASED type "plug", and it must be properly wired
    such that the neutral phase is tied to the lamp body.
  6. Bob Weiss

    Bob Weiss Guest

    Dead wrong, DimBulb.

    A polarized (not "phased") plug ensures that the screw shell of the bulb
    connects to neutral, but it does NOT ground the lamp frame.

    The metal lamp frame is left floating unless the lamp is provided with a
    3-wire grounding cord containing a separate green ground wire.
    Connecting the neutral to the lamp frame is poor practice, an NEC
    violation, and a serious safety hazard!

    Bob Weiss N2IXK
  7. DarkMatter

    DarkMatter Guest

    But it MUST be a PHASED type "plug", and it must be properly wired
    such that the neutral phase is tied to the lamp body.
  8. DarkMatter

    DarkMatter Guest

    Did you even read the statement he made? TWO conductor line cords
    ARE acceptable for lamps. IN THAT CASE, a phased type two prong plug
    IS used, and the neutral line IS the grounded element.

    Got clue?
  9. DarkMatter

    DarkMatter Guest

    The "lamp frame" and the bulb "screw shell" ARE common on every
    metallic lamp I have EVER examined. Try again.

    This is precisely the reason that phased type plugs and receptacles
    were introduced. IN fact, there was a time when a simple hand held
    drill was a two wire metallic cased affair, with one line connected to
    the shell. Put the plug in the wrong way on a concrete floor in bare
    feet, and give it a try. Please.
  10. DarkMatter

    DarkMatter Guest

    Guess you'd better run out to all those manufacturers, and tell them
  11. DarkMatter

    DarkMatter Guest

    To Quote Mr. Newton:

    This is related but does not answer your question.
    By the NEC metal floor lamps and table lamps do not have to be
    They are commonly and legally supplied by a two wire cord.


    What is says is that the old way is still acceptable.

    What is does not say is that a phased or "polarized" plug is
    required these days, and the outlets in ALL installations must also be
    of the polarized variety as well. This ensures that at least the line
    gets connected the same way every time.

    If a metallic lamp ever shorted its "hot" lead over to the body of
    the lamp, I for one, would want the neutral to be common to that lamp
    body as THAT would cause a breaker to disrupt the line. Without such
    grounding, a two wire style lamp could have a faulty condition where
    the "hot" lead is connected to the lamp body. This is unacceptable.
    What it says is that if one "full floats" the body of the lamp, either
    lead could end up connected to it. If that lead is the neutral, not
    much to worry about, if the lead is the "hot", then suddenly, the
    consumer product is rendered potentially deadly.

    In the case where the neutral is tied to the lamp body, such a
    potential hazard could not exist as a "hot" side connection would
    cause a shorted condition causing the line breaker to open, which is
    the desired effect.

    This is related but does not answer your question.
    By the NEC metal floor lamps and table lamps do not have to be
    grounded by a three wire cord. They are commonly and legally supplied
    by a two wire cord.

    Explain to us now, how leaving the lamp body open on a two wire line
    cord style metallic lamp is "safe".
  12. DarkMatter

    DarkMatter Guest

    No, that is how one describes you, keith.
    On a three wire attached device, I agree, however...

    This discussion is about items which are wired with a two prong
    cord, dipshit.
    You are lacking, boy. You lack brains, mainly.
    You're an idiot. You do not warrant further response, troll boy.
    Go away.
  13. DarkMatter

    DarkMatter Guest

    ANY two prong lamp can be "plugged in" incorrectly. Since plugs are
    design to break contact with both conductors together, your schema is
    difficult to reproduce.

    In any event, any two prong lamp can be as dangerous as you
    describe, whether one leg is common to the lamp body or not.
    A fault could allow connection of either side of the line to the lamp
    body. So with an unconnected frame, the same dangers exist.
    The likelihood that a plug is pulled out part way is less than
    the likelihood that a shorted hot lead on a grounded frame would

    On a grounded frame, the breaker opens. ON an ungrounded frame,
    your "dangerous" "hot lead" condition could occur, just the same
    without some lame "partially plugged in" circumstance.

    It should be disallowed by the NEC completely, and three prong plugs
    should be required on any metallic framed device, period.

    Don't any of you remember the old metal cased hand drills with
    non-polarized plugs? PLugged in one way, they were fine. Reverse the
    plug, and safety goes out the door, and danger steps in. This is the
    entire reason that electrical hand tools were changed to plastic
    shelled devices, and the entire reason that outlets and plugs were
    changed to polarized types.

    Y'all had better analyze this a bit more than just disclaiming my
    remarks, because if the NEC still allows two pronged cords on metallic
    devices, there IS a problem, no matter how it gets wired.
  14. DarkMatter

    DarkMatter Guest

    No shit.

    This again proves my statement that two wire cords should be
    disallowed for any metallic framed device that operates from the AC
  15. DarkMatter

    DarkMatter Guest

    Perhaps your lame ass should try constructing a valid response,
  16. Don Kelly

    Don Kelly Guest

    Not really- your original case was that the frame of the lamp should be tied
    to neutral.
    No one will disagree that a 3 wire system is best but in the situation where
    a polarised (not phased) plug is used, with the usual lamp socket
    construction, and where such lamps are generally used, the isolated case
    will be safer than a situation where one side of the plug is tied to the
    lamp frame. Hence the NEC code.
  17. DarkMatter

    DarkMatter Guest

    You research trolls are the worst.

    My posts do not show up on google, because google scans posts for
    profanity, and kills users that use same.

    It has nothing to do with the archive flag. The archive flag is set
    the way posts are supposed to be set. Doh! Bone up on usenet.

    Like I give a fat flying fuk if google carries my posts.
  18. DarkMatter

    DarkMatter Guest

    It is STILL a potential problem. Hence my statement that two wire
    cords on AC powered, metallic frame devices should ALL be banned.

    If the hazard potential is there, it should be disallowed. Period.
  19. DarkMatter

    DarkMatter Guest

    No shit.
  20. Bob Weiss

    Bob Weiss Guest

    I actually AGREE with you there.

    It is your ignorant (and potentiually lethal) statements about something
    as simple as the wiring of a floor lamp that people are calling your ass
    on. Funny how you keep trying to duck the subject...

    Bob Weiss N2IXK
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