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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:

    Type AC, in terms of standards-requirements or modern designs, shouldn't trip in any case where type A would not.  Rather, it's the failure of AC to trip in certain cases that makes A preferable. 

    That is my understanding. Perhaps type A was specified by the pesky boiler manufacturer to protect against faults after a rectifier, but I think that we are agreed that this is not necessary.

    However, modern RCD standards (whether for A or AC) require a test of immunity to false trips during transient residual currents. Some older RCDs that didn't have this requirement can trip easily on the brief residual currents through, e.g., a power-supply filter during turn-on or rapid changes in voltage.  I'm not sure where the boundary in time lies, but certainly the current IEC61008 specifies tests of transient immunity, whereas I've come across very [over]sensitive RCDs from the 1990s. 


    So it's true that changing an old RCD (which incidentally happens to be typeier AC) to a modern one (that's type A), would [edit: could] help avoid the false trips.  But I'd be surprised if it's because of the "type" in itself: it's because of another feature (transient immunity) that varies between old and new models.


    So what happens when e.g. a motor's controller fires up? I have a mental image of current in the line conductor going through a rectifier and then stopping in a capacitor until it is charged up. For that brief period, less would return via the neutral and the RCD might trip. Does that make any sense at all? ?


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  • 0
    Nathaniel:

    Type AC, in terms of standards-requirements or modern designs, shouldn't trip in any case where type A would not.  Rather, it's the failure of AC to trip in certain cases that makes A preferable. 

    That is my understanding. Perhaps type A was specified by the pesky boiler manufacturer to protect against faults after a rectifier, but I think that we are agreed that this is not necessary.

    However, modern RCD standards (whether for A or AC) require a test of immunity to false trips during transient residual currents. Some older RCDs that didn't have this requirement can trip easily on the brief residual currents through, e.g., a power-supply filter during turn-on or rapid changes in voltage.  I'm not sure where the boundary in time lies, but certainly the current IEC61008 specifies tests of transient immunity, whereas I've come across very [over]sensitive RCDs from the 1990s. 


    So it's true that changing an old RCD (which incidentally happens to be typeier AC) to a modern one (that's type A), would [edit: could] help avoid the false trips.  But I'd be surprised if it's because of the "type" in itself: it's because of another feature (transient immunity) that varies between old and new models.


    So what happens when e.g. a motor's controller fires up? I have a mental image of current in the line conductor going through a rectifier and then stopping in a capacitor until it is charged up. For that brief period, less would return via the neutral and the RCD might trip. Does that make any sense at all? ?


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