Retired Maintenance Electrician. Replaced faulty consumer unit with dual RCD (30ma) type. Split circuits between upstairs and downstairs. Needed to run a supply into garage so used 1 x 32 amp breaker (protected by RCD as they all are) and wired this into an MK 2 x way Sentry garage unit which is governed by 30 ma RCD. Tried lights and RCD tripped, likewise sockets. This was linked to mixed neutrals in the RCD. Rewired Senty unit in garage direct to mains in Consumer Unit and everything is working. Does this conform to latest regulations. Polarity and earthing are all correct.