Hi guys I am rather perplexed as I have recently fitted a dual RCD Sentry (App 3 compliant) consumer unit. I am suffering a random tripping pattern with one of the RCD's (63A, 30mA) which sometimes pops the other (80A 30mA) at the same time. I have stripped everything down and insulation resistance tested everything with the lowest reading being 80Mohm L-E and N-E. I also tested with the IR test between neutral bars to ensure I do not have crossed neutrals or some random connection between them. I decided to do a ramp test on both RCD's just to see what they are actually tripping at and was surprised to get random readings on a completely disconnected RCD of 6mA (multiple times) with an occasional 21mA. Both RCDs were similar so I changed both (Screwfix supplied) and they are the same. My tester is new and is a Kewtech KT63. As a matter of curiosity I ramp tested a BG RCD with the same tester in place of the MK ones and the ramp test was consistently 21mA. Any ideas guys? My next move is to fit the BG as a temporary test and then call MK Tech Support. Thanks!