I have used the solution of putting an additional light in off the other RCD in a dual RCD to the one that supplies the lighting that is already in place in the consumer unit location.


There are various options, the only one that is no longer available is using a non-RCD spare way. Not the biggest of problems! There’s always the option of putting in a fifteen quid emergency light fitting costing less than a RCBO and you need some sort of light fitting anyway.


Andy B.

BS 7671. Reg. 411.3.4. "Within domestic (household) premises, additional protection by an RCD with a rated residual operating current not exceeding 30mA shall be provided for all AC final circuits supplying lumnaires."


Well, a battery operated camping lamp screwed to the wall in the cupboard under the stairs, or a hand torch conveniently hung on a hook could be used if a breaker trips off. Simple and inexpensive, and independent of the regs.

Unfortunately it is getting more and more difficult to find any domestic circuit that does not require an RCD. Building regulation state that Switches and Socket outlets must be installed between a height 450mm and 1200mm, so not any sockets 'out of reach'. I don't think it will be long before even all circuits in Commercial and Industrial installations will require RCD protection.

Why is it unfortunate that circuits in dwellings require RCDs? Does it not afford increased protection?


I know RCDs are not perfect, but for general purpose RCDs the cost has come down so much it seems odd to want to avoid using them?

The question I originally asked was how long before all domestic circuits have to have RCD protection, by which I meant 30 mA RCD protection .


Generally all the  domestic circuits I install do have that RCD protection,  don't get hung up on lights that is just the latest group of domestic  circuits that must have RCD protection and normally all of the circuits I installed do so, but up until now you justifiably omit it if you got the circuit design right,  but now you cannot. 


Andy B.

Probably not long Andy.

I usually mention the advantage of an emergency light near the supply.

Or sometimes its own lcal RCBO circuit.

I tend to go the Plain isolator and seperate RCBO route, costs more but is a bit more resilient.

If it must be a dual RCD board then I tend to use a few RCBO circuits for shower, cooker and boiler for instance, again adding some resilience.

RCDs can make things safer and in my experience problems are rarer than some tink might be the case.

Having said that we must not lose sight of two things 1/ Working RCDs might only save 95% of the population (5% not saved!) 2/ They might have a failure rate of up to 7%.

I think one danger is, in line with all other safety devices, people take greater risks if they know they`ve got additional safety such as an RCD - more folk drive like maniacs because they have airbags and crumple zones

In practical terms, I suspect that the only non-RCD protected one now would be an SWA distribution circuit to a detached garage.

Chris Pearson:

In practical terms, I suspect that the only non-RCD protected one now would be an SWA distribution circuit to a detached garage.

However if you TT the detached garage is that an option?


Andy Betteridge

100mA Type S feeding SWA then 30mA circuit(s) at end?

In which case yes RCD protection of submain albeit not 30mA