Need for Additional protection for circuits serving zones 1 and 2 in a bathroom

I am confused because the regs seem to contradict themselves.

Not really, as the new regs only apply to new work. It's entirely possible to say add a new circuit to a bathroom, have the new work fully comply with the latest regs, but still be in the situation of not being able to meet all the conditions for omitting supplementary bonding. E.g. if you add a new 30mA RCD protected shower circuit, but the existing lighting circuit is not RCD protected - you'd still need supplementary bonding (or change the lighting circuit to have 30mA RCD protection of course).


It's not all just about RCD protection for the bathroom circuits either - if pipework for example could import a fault from outside the bathroom (especially from a say 5s disconnection time circuit) then it's likely that supplementary bonding would still be needed even though all the bathroom circuits had 30mA RCD protection.


On the other hand, it's usually possible to add 30mA RCD protection without a full CU change - e.g. adding a separate enclosure next to the CU for a RCCB for the shower circuit is perfectly acceptable electrically.


Arguably if it's an existing circuit and you're simply replacing the appliance like-for-like, there's no requirement to bring the existing circuit up-to-date. Most would probably recommend taking the opportunity to do so - and the manufacturer's instructions for the new unit would most likely ask for 30mA RCD protection - but there might be a modicum of wiggle room there.


    - Andy.

I am confused because the regs seem to contradict themselves.

Not really, as the new regs only apply to new work. It's entirely possible to say add a new circuit to a bathroom, have the new work fully comply with the latest regs, but still be in the situation of not being able to meet all the conditions for omitting supplementary bonding. E.g. if you add a new 30mA RCD protected shower circuit, but the existing lighting circuit is not RCD protected - you'd still need supplementary bonding (or change the lighting circuit to have 30mA RCD protection of course).


It's not all just about RCD protection for the bathroom circuits either - if pipework for example could import a fault from outside the bathroom (especially from a say 5s disconnection time circuit) then it's likely that supplementary bonding would still be needed even though all the bathroom circuits had 30mA RCD protection.


On the other hand, it's usually possible to add 30mA RCD protection without a full CU change - e.g. adding a separate enclosure next to the CU for a RCCB for the shower circuit is perfectly acceptable electrically.


Arguably if it's an existing circuit and you're simply replacing the appliance like-for-like, there's no requirement to bring the existing circuit up-to-date. Most would probably recommend taking the opportunity to do so - and the manufacturer's instructions for the new unit would most likely ask for 30mA RCD protection - but there might be a modicum of wiggle room there.


    - Andy.