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Is this safe?

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    #32
    Zen65
    Registered Users Posts: 2,630 ✭✭✭Zen65


    tomdempsey200 wrote: »
    you'll pick it up on the non contract testers for sure

    Yes, non-contact phase testers will light from a fairly low voltage. Induced voltages normally require long lengths of line (such as you might find on a network) running parallel. That's hard to replicate in a home.


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    #33
    tomdempsey200
    Registered Users Posts: 1,890 ✭✭✭tomdempsey200


    Zen65 wrote: »
    Yes, non-contact phase testers will light from a fairly low voltage. Induced voltages normally require long lengths of line (such as you might find on a network) running parallel. That's hard to replicate in a home.

    we'll leave that discussion open yet

    i'm nearly sure it was a common occurrence back in the day if I recall


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    #34
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    Zen65 wrote: »
    If the MCB is tripped then (assuming he has the MCB connected correctly to the phase) the live voltage you are seeing is likely to be a back-feed on the neutral? Neutrals are not always at earth potential when an appliance in the house is switched on.

    The cable the op got a shock off may have been an old circuit reused and hence the confusion with the mcbs.


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    #35
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Zen65 wrote: »
    Yes, non-contact phase testers will light from a fairly low voltage. Induced voltages normally require long lengths of line (such as you might find on a network) running parallel. That's hard to replicate in a home.

    It can and is replicate at home. A phase tester will dimly Lights on a light holder that's fed from 2 way switching.

    A Digital voltmeter will also display a few volts at times on the same light sockets.

    Since no current is flowing on such strappers, it's likely capacitance rather than induction.


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    #36
    tomdempsey200
    Registered Users Posts: 1,890 ✭✭✭tomdempsey200


    yes
    I seem to recall the false readings on phase testers years ago

    I think it's only the diy people that use them now

    how long have the non-contact testers been available?

    I remember esb personnel with them years before I ever bought one


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    #37
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    tomdempsey200 wrote: »
    yes
    I seem to recall the false readings on phase testers years ago

    I think it's only the diy people that use them now

    how long have the non-contact testers been available?

    I remember esb personnel with them years before I ever bought one
    They are actually giving true readings for circuit conditions really.

    A digital multimeter across the 2 pins of the bulb holder will also show a fair few volts at times, where an analog one will show zero more or less.

    Both are reading correctly for their properties in the circuit, the massive high impedance digital meter able to read the completely unloaded induced voltage without affecting it, while the far lower impedance moving coil meter imposes enough of a load to pull the induced voltage down to nothing, even though its circuit loading is negligible enough.


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    #38
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    tomdempsey200 wrote: »

    I remember esb personnel with them years before I ever bought one

    Yea I had one of them ones in about 1990.

    Got another one the exact same 3 or 4 years ago. Very handy. Audio indication, very positive indications. Handy for identifying uncut cables and their MCB,s. Or what MCB is doing certain sockets or lights as you can hear it from different rooms in a house while at the DB.


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    #39
    Mycro
    Registered Users Posts: 152 ✭✭Mycro


    Anyway, the bottom line is this. The exposed wiring for that yet-to-be- installed socket that was supposedly isolated at the board was in fact live.

    I'm glad I went with my intuition and asked the contractor to get rid of the original electrician at the first sign of unsafe work. Unfortunately it didn't stop me getting a shock even after that. I am only glad no kids grabbed that wire.

    There is a new crew in the house now and they are checking all the new wiring quite thoroughly.

    At the same time, I cannot believe anybody would connect exposed wires to a board.


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