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Electric safety rule ?

Discussion in 'Electronic Basics' started by [email protected], Jan 9, 2006.

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  1. Guest

    Some years ago a guy promoting his anti-rust spray, he clam that the
    anti-rust spray have good dielectric, he than spray on the lamp holder
    & put in to a pail of water with power switch on,
    this surprise me that does't shot circuit. This recall me that some
    kattle ( found in the hotel ) ,
    the heater element connected to the live wire was not insulated in the
    water, but it does not cause any electrical problem when boiling the
    water.
    It had confuse me in the electrical safety rule, that is live wire
    should not contact with water.
    Can any members help me in this questions ? Thanks.
    Regards.
     
  2. Relatively clean water has enough resistance so that only a moderate current
    will flow Also, the bucket is isolated from ground (I'd use a plastic one).
    I'd not sit in a bathtub and for that kind of demonstration, however.
     
  3. Jasen Betts

    Jasen Betts Guest

    possibly he was using de-ionised water :)
    because the water in the vessel is not in electrical contact with anything
    outside the appliance.
    do not pour the water into a metal pan while the kettle is plugged in.
     
  4. Guest

    The heater element in the kettle...I guess thats what you mean ...like
    an electric tea kettle..... is insulated. The nichrome heater element
    is encased in a insulating material inside the outer tube.
     
  5. John G

    John G Guest

    No.. thats not entirely true.

    In some countries (Aus for example) There were electric jugs which were
    just a pottery jug, with a plastic lid to keep your fingers out, and
    the element was an EXPOSED coil of tungsten on a porcelain former in
    direct contact with the water.
    At 240 volts they worked great. Predecessor of Fast Heat Kettles.

    A simpler water boiler was a tinplate container of about 1/2 a gallon
    with 2 electrodes suspended in the water and connected directly to the
    240 volt mains. Boiled the water quite soon or sooner if the water was
    harder. Of course this setup would not qualify as DOUBLE Insulated nor
    would it get UL Approval.
    But boys will be boys. What adventures our children are missing.
     
  6. Jasen Betts

    Jasen Betts Guest

    no. not always. some of the older ones had bare nichrome, I've seen some
    that heated by conduction too.

    Bye.
    Jasen
     
  7. Rich Grise

    Rich Grise Guest

    What you saw, that you thought was the heating element, was only the
    external casing, or jacket, for the actual heating element. The heating
    element is insulated from the casing by some sort of electrically
    insulating, but heat-conductive, material.

    Hope This Helps!
    Rich
     
  8. Guest

    Thanks members for fast response, may i rephrase the question, the
    question is why it does't blow the fuse or explode as the elememt
    (non-insulated ) was submerge in the water or may be hydrogen and
    oxygen form between the two elements when power turn on ?
    Regards.
     
  9. Rich Grise

    Rich Grise Guest

    A, it's probably not "non-insulated", it just _looks_ like it. Get
    out your meter and check!

    And B, ordinary water is a good enough insulator that its resistance
    across the terminals will be orders of magnitude higher than the
    resistance of the element.

    Here's an experiment - dissolve a couple of spoonfuls of salt in
    your water, and see if _that_ shorts it out!

    All of the standard disclaimers apply, of course. :)

    Good Luck!
    Rich
     
  10. John G

    John G Guest

    I can assure you the device known as an Electric Jug and use by most
    austalians to boil water for tea or coffee for many years had a bare
    wire element wrapped around a porcelain rectangle about the size of a
    match box and suspended by the conecting rods directly into the water.
    The power was pluged into a connector under the hinge of the lid so it
    was not possible to put anything in the water without first removing the
    power.

    There are several for sale on Ebay.
    http://search.ebay.com/electric-jug_W0QQfkrZ1QQfnuZ1QQfromZR8

    On this link there is a picture of the element alongside the jug.
    http://cgi.ebay.com/OLD-SPEEDIE-ELE...ryZ13933QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
     
  11. Guest

    Hi John.You are right. I got this electric jug from Austalia during my
    holiday. Thanks
    Regards
     
  12. Jasen Betts

    Jasen Betts Guest

    it does produce hydrogen, but because if the high voltage most of the energy
    goes into heating the water.

    if you were to put salt water in there it would blow the fuse. but tap
    water has low enough conductivity to have most of the current flowing in
    the nichroome.

    Bye.
    Jasen
     
  13. Jasen Betts

    Jasen Betts Guest

    yeah I've seen them (In australia) we never had them in New Zealand the
    rods were metallic (brass?) and uninsulated and ran directly too the
    bolts that backed the contacts for the "plug" (inline socket) on the end
    of the power cord.
    I saw one that had two metal disc electrodes in the bottom spaced about
    15mm apart. could be interesting if that one boiled dry.

    Bye.
    Jasen
     
  14. Rich Grise

    Rich Grise Guest

    Will someone please take an ohmmeter to one of those elements? Anything
    uninsulated on the mains is a death trap, and I can't imagine any
    civilized country allowing such a thing to be sold. Doesn't Aus. have
    something like UL or CSA?

    Thanks,
    Rich
     
  15. Pooh Bear

    Pooh Bear Guest

    IEC. Like the rest of the world. UL/CSA applies only in N.America.

    Graham
     
  16. John G

    John G Guest


    Yes it is UNinsulated and yes in careless hands could be dangerous but I
    can not remember a problem being reported.
    We do have a certification authority and these have been OFF the market
    for many years now.
     
  17. Jasen Betts

    Jasen Betts Guest

    It's 22awg approx nichrome wire, I doubt very much that they have a
    way to insulate anything that fine.

    when the cord is attached it's impossible to open the lid of the jug more
    than a crack.

    as far as safety it doesn't seem much worse than an electric toaster...
    These devices are antiques...

    Bye.
    Jasen
     
  18. Bob Masta

    Bob Masta Guest

    What about those cheapie "vaporizer" humidfiers? Been a few
    years since I looked at one, but as I recall it was just a couple
    of electrodes immersed in a chamber of water. (You had to add
    salt if your water wasn't conductive enough.) Seems like that
    is not so different than the jug from Oz.

    Best regards,



    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
    Home of DaqGen, the FREEWARE signal generator
     
  19. Guest

    I have seen a electric stove made in china with bare heater wire expose
    without any cover, it arange like " snake coil ". This also post danger
    when you put the metal container on top of the wire with only 5 mm
    spaeing, but did not hear any bad news !
    Regards
     
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