Hi, bit green on distribution circuits and need advise please! I have been asked to convert an outside socket to a Caravan hook-up that meets 18th Edition (interlocked switches and 2 x 16amp RCBOs 30ma) feeding 2 x 16amp commandos where I will convert to a TT system. The installation as stands is as follows: - TNCS main Feed to - 32 amp breaker protected by 30ma RCD (Garage UNIT) to - 70 metre approx buried 16mm swa cable run - Caravan Hook-up (as above) - ZS @ distribution point 0.48 Ohms (calculated) Any thoughts ...is this how you would do it? My main question is this now considered a 'Distribution Circuit' in which case my permitted disconnection times would change? I am reading definitions and still confused as whether the caravan hook-up is considered another CU as before the ZS values would be well within permitted if just outdoor sockets. Normally I wouldn't use 30ma RCD's in sequence but as I'm converting the caravan hook-up to TT then I'm assuming this would prevent any tripping that would take out the whole circuit (?) I know an old school approach would be to front it with a 100ma S type. Thanks ... I'm also getting conflicting advise on the old 'exporting a PME' issue !