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Type A RCBO?

Discussion in 'Electrics UK' started by RyanM, 5 Sep 2013.

  1. RyanM

    RyanM

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    Where can you find Type A RCBOs rather than Type AC?

    Just I want to install a car charger, which has a build in RCD itself, but I believe that will be on the secondary side of the transformer, so obviously I need one from the DB.

    It needs to be a Merlin Gerin/Schneider/Moeller to fit in the board.

    I've read on here that normal RCBOs will try all the time, so Type A ones are needed?



    Cheers
     
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  3. davelx

    davelx

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    Mine's on a normal RCBO - not had a trip yet. (Voltec system)
     
  4. RyanM

    RyanM

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    Oh right, I'd read 'special' ones were needed?
     
  5. JohnW2

    JohnW2

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    I thought the issue was not about 'nuisance tripping' but, rather, that if the load was such as there was a 'pulsating DC component' to the current, this could seriously impair the function of a 'standard' (Type AC) RCD or RCBO. The Wylex documentation says that the presence of a pulsating DC component to the current may "partially densensitise or totally disable a normal Type AC RCD/RCBO".

    In other words, using a Type AC device with such a load might well not result in any nuisance trips, but would be potentially 'unsafe' in that the device might not trip 'when it was meant to'. Whether or not the sort of chargers we're talking about result in such a current I haven't got a clue.

    Kind Regards, John
     
  6. RyanM

    RyanM

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    Hi John,

    Thanks for the reply!

    Where online can you purchase the Type A RCBO? I can't seem to find any?



    Thanks
     
  7. JohnW2

    JohnW2

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    If you google "Type A RCBO", you will find thousands (even after discounting the ones on ebay, which I'd be reluctant to recommend). Just one example, at random ... click here

    However, I, for one, don't have a clue as to whether or not your charger would/could result in the sort of current waveform which would require a Type A device. What does the manufacturer of the charger say about this in their documentation?

    Kind Regards, John
     
  8. RyanM

    RyanM

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    Ok, thanks :)

    I've not received the charger yet to be honest.
     
  9. JohnW2

    JohnW2

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    Fair enough - but you might be able to find documentation on-line. Do you know exactly what make and model you're going to be getting?

    Kind Regards, John
     
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  11. Spark123

    Spark123

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    What make of board is it? I'm not sure about Moeller - the ones I have seen are different to Merlin Gerin which is now re-badged as it's parent company Schneider.
     
  12. RyanM

    RyanM

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    Hi,

    It's a Schneider board. I cannot seem to find any RCBO's to fit though? Are they available, or only available in RCDs rather than RCBOs?

    So I may have to install a MCB in the DB, then use a seperate box to house the RCD? I'd rather not as it is more work, but I can't seem to find any correct RCBOs.

    The charger is a Pod Point Solo II, SL-1651-1-PP. 3.7kW @ 16A.



    Thanks a lot
     
  13. ericmark

    ericmark

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    I seem to remember looking for a Type A in my sons boat because of the simulated sin wave from the inverter and the worry that with a fault the AC would not trip. So I asked around other residents of the maria who had inverters and they allowed me to test. Most had type AC and on the inverter supply they all tripped within the 40ms allowed.

    On shore supply there was very little difference in the tripping times and most were supplying switch mode 3 stage battery chargers as their main load which were running at time of test.

    As a result we continued to use a type AC. As to if different makes of type AC will react in a different fashion I don't know it was a very small sample.

    However you talk about fitting a Schneider/Merlin Gerin board and from memory the all pole RCBO to fit those boards are in fact two units which combine together doubling up on the ways used. Clearly the neutral was taken from the centre rail of the Merlin Gerin board. I only ever used the three phase versions but they were not suitable for a standard domestic consumer unit as there is no neutral rail on the domestic versions.

    So considering the car charger will need the neutral switching using a separate RCD will likely be the only option. (Assuming not fitted inside a building)

    Found the units Vigi says type SI
     
  14. RyanM

    RyanM

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    Hi,

    Thanks for the reply.

    They are only single phase chargers, so a RCBO should fit straight in? The only problem is finding the Type A.

    The manufacturer and recommended the Type A over AC due to nuisance trips, so ideally I would like to source a type A RCBO, but cannot seem to find one to fit.

    Something like this, but Type A:
    http://www.schneider-electric.co.uk...ltage-protection/combined-mccb-rccb/rcbo.page




    Cheers
     
  15. Spark123

    Spark123

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    It says they are available in type A on that page, as others have pointed out the single module ones are single pole switching i.e. only the phase is switched, the neutral isn't.

    For example a 16A class A RCBO C curve is part number C60HC16RA30.
    An AC class is C60HC16R30.
     
  16. ericmark

    ericmark

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    The big question is if the car being charged is inside or outside the building. If inside then single pole switching RCBO is OK if outside then would need to be double pole switching so the RCBO you show would be no good to supply the power with a TT set-up where the vehicle is outside.

    Standard IEC 60755 (General requirements for residual current operated protective devices) defines three types of RCD depending on the characteristics of the fault current.

    Type AC: RCD for which tripping is ensured for residual sinusoidal alternating currents

    Type A: RCD for which tripping is ensured as for type AC for residual pulsating direct currents for residual pulsating direct currents superimposed by a smooth direct current of 6 mA, with or without phase-angle control, independent of the polarity.

    It is not the tripping when it should not trip that is the problem with type AC but it not tripping where it should trip. From what
    I read here it would seem the Type SI is a type A anyway so fitting a type SI would fit the bill.

    However the question has to be will the Vigi unit fit on a single pole MCB. It was back in 2004 when I used these units and sorry just can't remember how the neutral was connected.
     
  17. JohnW2

    JohnW2

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    Indeed - I made that point early in the thread, so I don't really understand why the manufacturers of the charger are recommending a Type A 'to reduce nuisance trips'. One suspects that they don't know what they are talking about!

    Kind Regards, John
     
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