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RCD selection and BS7671:2018+Amendment 2:2022

sparkiemike


My question relates to the latest regulations (BS7671:2018+Amendment 2:2022) and RCD selection.

I have an existing installation with an upfront 30mA type-AC RCD.

I am quoting for some work where there will be some electrical alterations for a new kitchen. No new circuits! Mainly some new sockets and LED lighting and relocating a cooker cable. So DC components will be introduced.

Is there a requirement to upgrade the RCD to a type-A RCD to comply with 531.3.3?

Are others anticipating fitting type-A rcds on their minor works now e.g. 4 new downlights in bathroom?

The current board is obsolete so either I put a different manufactures kit in to the board or a new consumer unit. Understandably the customer is reluctant to spend any more money

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  • 0

    What is this tripping and blinding all about?

    Surely if an appliance blinded an RCD, it wouldn't trip even if it was meant to.

    I have had a VSD which tripped a type AC RCD (in fact an SRCD), but not a type A. Perhaps the former was a little more sensitive than the latter but in any event, the VSD turned out to be defective.

    The risk, I think, is that for example, a defective immersion heater or worn flex will leak an AC waveform and a type AC RCD will be just fine. If there is a rectifier in an appliance, then a fault after it may introduce "pulsed" DC so a type A RCD is required to guard against that possibility.

    If the LED or cooker manufacturer specifies a type A RCD, that is what should be fitted.

    I thought through all of this when step-daughter's boiler was installed. It should have a type A RCD, but the board (Schneider Easy 9) has AC ones. Type A ones seem to be hard to come by and in any event tight-fisted hubby has ignored my recommendation. So which is the problem? (1) A risk of a fault in the boiler, in which case one simply keeps one's fingers crossed; or (2) that the type AC will trip, in which case matey will have to spend a few shekels or be cold next winter?

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  • 0

    What is this tripping and blinding all about?

    Surely if an appliance blinded an RCD, it wouldn't trip even if it was meant to.

    I have had a VSD which tripped a type AC RCD (in fact an SRCD), but not a type A. Perhaps the former was a little more sensitive than the latter but in any event, the VSD turned out to be defective.

    The risk, I think, is that for example, a defective immersion heater or worn flex will leak an AC waveform and a type AC RCD will be just fine. If there is a rectifier in an appliance, then a fault after it may introduce "pulsed" DC so a type A RCD is required to guard against that possibility.

    If the LED or cooker manufacturer specifies a type A RCD, that is what should be fitted.

    I thought through all of this when step-daughter's boiler was installed. It should have a type A RCD, but the board (Schneider Easy 9) has AC ones. Type A ones seem to be hard to come by and in any event tight-fisted hubby has ignored my recommendation. So which is the problem? (1) A risk of a fault in the boiler, in which case one simply keeps one's fingers crossed; or (2) that the type AC will trip, in which case matey will have to spend a few shekels or be cold next winter?

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