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RCD x 5

lyledunn
apologies if you are already aware of this but with respect to the x5 or greater test current introduced in the 18th, Hager have advised that their RCBO units are manufactured to the 2017 amended version of BSEN61008/9 which permitted disconnection within 40ms at 250mA. Thus they advise testing at x 5 on both sides with the instrument set for 50mA on the variable range.
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    AJJewsbury:




    Something must have been lost in the translation.


    Testing at 250mA would not be RCD x 5, would it?



    That's the point - it seems the standards have changed so that 5x IΔn is no longer the requirement. You might have noticed that all the requirements for a 30mA RCD used for additional protection to have 'an operating time not exceeding 40ms at a residual current of 5 IΔn'  vanished completely from the 18th Ed - the requirement is simply for a 30mA RCD now. We seem to be discovering why....


    I'm trying to imagine why such a change would have been thought a good idea - after all we certainly have the technology to achieve 40ms at 150mA - maybe it's to allow the RCD to ignore the sort of transients that can lead to 'unwanted tripping' or some such.


    BS EN 61008 has allowed testing at 250 mA instead of 5 x IΔn since at least 2001 (1995:Amd3) for RCDs with an IΔn <= 30 mA, so nothing new there. Perhaps it was felt that BS 7671 should be brought into line with the standard for the devices?

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  • 0

    AJJewsbury:




    Something must have been lost in the translation.


    Testing at 250mA would not be RCD x 5, would it?



    That's the point - it seems the standards have changed so that 5x IΔn is no longer the requirement. You might have noticed that all the requirements for a 30mA RCD used for additional protection to have 'an operating time not exceeding 40ms at a residual current of 5 IΔn'  vanished completely from the 18th Ed - the requirement is simply for a 30mA RCD now. We seem to be discovering why....


    I'm trying to imagine why such a change would have been thought a good idea - after all we certainly have the technology to achieve 40ms at 150mA - maybe it's to allow the RCD to ignore the sort of transients that can lead to 'unwanted tripping' or some such.


    BS EN 61008 has allowed testing at 250 mA instead of 5 x IΔn since at least 2001 (1995:Amd3) for RCDs with an IΔn <= 30 mA, so nothing new there. Perhaps it was felt that BS 7671 should be brought into line with the standard for the devices?

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