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Type A rcd . EICR coding ? etc

aligarjon
Hi Guys.   Not been on for a long time, just had a bit of a search and couldn't really find anything so thought i would ask and see what you all thought.


1.  Are we or will we be coding type AC rcd's if there are LED's or induction hobs, lots of electronics  etc  present.

2. How much DC leakage does it actually take to saturate an rcd and cause  problem?

3. How much does a standard LED lamp or induction hob  leak ?

If we test an AC RCD with no load and it's fine then re-test it with all LED lights, induction hobs etc turned on and it operates correctly could we then say that it is ok with a note on EICR  OR EIC if installing any of the above.  


Obviously also on an EICR if the RCD then doesn't operate with it all on it becomes a C2 ?


Any thoughts



Gary
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  • 0
    Nathaniel:

    However, note that it's not just devices with a single-diode rectifier that could give a half-wave rectified residual current. A bridge rectifier can do this too, from either of its dc outputs. So half-wave rectified residual currents can arise from the wires and components that come after a rectifier inside an appliance, if these touch the frame or if a person directly contacts such parts.


    This begs the question, "What is additional protection for?"


    The obvious answer is to protect from direct contact when you have just mown or trimmed a power lead in the garden.


    If there is a fault of negligible impedance just downstream of a rectifier, which is close to the supply of a piece of equipment, wouldn't ADS operate?


    However, even if the fault is of negligible impedance, the circuitry between it and the supply terminals may have a resistance of several ohms so that even a BS 1362 fuse does not blow. Presumably, however, the touch voltage would be < 50 V.


    Then I thought about a fault and circuitry which together have an impedance of say 8 kΩ so now we have a fault current of 29 mA and off she trips. So now I wonder whether some nuisance tripping of electronic devices is in fact due to a fault somewhere in the circuitry.


    Is additional protection designed to protect us from relatively high impedance faults in equipment, or is it just fortuitous?


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  • 0
    Nathaniel:

    However, note that it's not just devices with a single-diode rectifier that could give a half-wave rectified residual current. A bridge rectifier can do this too, from either of its dc outputs. So half-wave rectified residual currents can arise from the wires and components that come after a rectifier inside an appliance, if these touch the frame or if a person directly contacts such parts.


    This begs the question, "What is additional protection for?"


    The obvious answer is to protect from direct contact when you have just mown or trimmed a power lead in the garden.


    If there is a fault of negligible impedance just downstream of a rectifier, which is close to the supply of a piece of equipment, wouldn't ADS operate?


    However, even if the fault is of negligible impedance, the circuitry between it and the supply terminals may have a resistance of several ohms so that even a BS 1362 fuse does not blow. Presumably, however, the touch voltage would be < 50 V.


    Then I thought about a fault and circuitry which together have an impedance of say 8 kΩ so now we have a fault current of 29 mA and off she trips. So now I wonder whether some nuisance tripping of electronic devices is in fact due to a fault somewhere in the circuitry.


    Is additional protection designed to protect us from relatively high impedance faults in equipment, or is it just fortuitous?


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