Just to hurl another moggy in... so the general consensus is that using an RCCB as a main switch is not considered good practice due to the 'convenience factor' meaning it doesn't meet the minimum split load requirements of the 17th, but... how about a household with 16 circuits split equally over 2 separate crabtree boards - one board uses 80A RCCB as main switch whilst the other has a 100A DP as main switch and no RCD protection (this isn't hypothetical, btw, but characteristics of a property I worked at recently). If the 100A DP was swapped for an RCCB (80A would easily meet the everyday requirements of the board), would this be deemed good practice as it would effectively give the same level of protection and convenience as an upgrade to a split load 16-way board at a fraction of the cost to the client? Apologies for the verbal diaorrhea...:smiley2: