Is Rcb spur needed?

[Proper Job]

Hi all.
i am about to run some cables for outside lights and a pond ( pump and filter). The source of which is a switch in the conservatory, which is not on an rcd but but I am going to up grade the breaker to an rcbo.
now I can not run a new supply to feed the outside lights, that would have been my preference and I am concerned about future tripping from the pond especially considering the internal rooms on this circuit,so is it a good idea to bring the feed entering the switch down to a fused rcb spur and then back to the swich to feed the lights (. It is in a stud wall so no probs with fishing a cable)
The lighting circuit supply's the kitchen ,garage and another couple of rooms so I am hopping that by adding the outside lights onto this circuit with a Rcb spur, that if a problem did occur outside that the spur would trip out first?

 

[Pete999]

If you have a 13a socket circuit in your conservatory, is it RCD protected? if yes the feed your pump and filter from that circuit via a fcu, if no RCD the simply supply the pump via a rcd fcu

 

[Deleted member 9648]

Both RCD's will trip,an RCD works by detecting an imbalance in the live and neutral feeding through the RCD.Therefore if there are two RCD's on the supply side of the fault both will see the imbalance and trip.

Should this be in the DIY forum?

 

[Proper Job]

The aim is to have both the outside lights and the pond on the switch bank.
wirepuller I was just curious as to wether the red spur would trip first as it is closest to the fault should one occur. It may sound stupid to you but it is just some clarification in my head that I need. Thanks

 

[Deleted member 9648]

The aim is to have both the outside lights and the pond on the switch bank.
wirepuller I was just curious as to wether the red spur would trip first as it is closest to the fault should one occur. It may sound stupid to you but it is just some clarification in my head that I need. Thanks

I didnt say it was stupid,it doesnt sound like a question from an electrician though,hence my suggestion that it should be in the DIY forum.

 

[sparks1234]

I would make sure its through a double pole switch and at least you can then isolate it, no point putting an extra RCD if you're putting an RCBO in