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RCBO's and IR testing

Jaymack
I have had a problem with 5 off Wylex RCBO's. These were bought by a houseowner and fitted by him as there was no RCD protection for some circuits requiring such. These Wylex RCBO's have a warning hidden on the body that connections should be disconnected for Insulation Testing ..........too late the man cried!. For expediency and availability, I have redesigned the arrangement to have MCB's with a common RCBO as a M.S..

I have been in contact with Wylex technical help, who say that they should have been OK to withstand 250V IR testing as in this case, but to return them to the dealer. Anyone else have had similar problems?


Jaymack .
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    AJJewsbury:

    What happened to the RCBOs?


    In a way I'd expect them to survive - after all (looking at table 443.2) they should be able to withstand a 4kV pulse - so 500V should be fine (at least for a short duration). If they failed on a 250V d.c. test I can't imagine how they'd work in service where a 230V r.m.s. waveform peaks at over 325V.


    Sure most need disconnecting (a few sensible designs notwithstanding) - but for reasons of not causing false failures of the test rather than (I'd hope) risking the RCBO itself.


      - Andy.




     

    I agree with the comments here, the RCBO's have open circuited and had to be replaced, in this case with MCB's and a common old garden Main Switch, (not an RCBO as I stated). If the case that connections require to be removed for testing, then this warning notice should be "In your face" as a sticky. Though what a chore where a quantity of these units are used for redundancy of circuits!. 

    In the meantime, I will arrange for these to be returned to the supplier for analysis by Wylex; I doubt that the supplier will give a refund at this stage however. At this stage, it seems that Joe Public is the final tester and the market is the ultimate test bed. Such is progress .............. a la Boeing. This is a Wylex product, but is the same applicable to other makers?, are the common manufacturing standards at fault? .


    Jaymack.    .
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  • 0

    AJJewsbury:

    What happened to the RCBOs?


    In a way I'd expect them to survive - after all (looking at table 443.2) they should be able to withstand a 4kV pulse - so 500V should be fine (at least for a short duration). If they failed on a 250V d.c. test I can't imagine how they'd work in service where a 230V r.m.s. waveform peaks at over 325V.


    Sure most need disconnecting (a few sensible designs notwithstanding) - but for reasons of not causing false failures of the test rather than (I'd hope) risking the RCBO itself.


      - Andy.




     

    I agree with the comments here, the RCBO's have open circuited and had to be replaced, in this case with MCB's and a common old garden Main Switch, (not an RCBO as I stated). If the case that connections require to be removed for testing, then this warning notice should be "In your face" as a sticky. Though what a chore where a quantity of these units are used for redundancy of circuits!. 

    In the meantime, I will arrange for these to be returned to the supplier for analysis by Wylex; I doubt that the supplier will give a refund at this stage however. At this stage, it seems that Joe Public is the final tester and the market is the ultimate test bed. Such is progress .............. a la Boeing. This is a Wylex product, but is the same applicable to other makers?, are the common manufacturing standards at fault? .


    Jaymack.    .
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