I would like to take power to a garden water feature from a spur off the conservatory ring circuit which is RCD protected via a switched FCU to be installed in the conservatory, the cable run being in 2.5 SY cable to the water feature. It has been suggested that it might be better to go via an RCD unit instead of a standard FCU, but in the event of a fault in the garden with both RCDs being 30mA would discrimination take place or would I be wasting money with a 2nd RCD.I am aware of building regulation part P and works will be inspected, tested and submitted. Please could you advise. Happy new year to all who participate in this great forum