I have recently upgraded my shower which I protected with a 45amp mcb. As a result my split load CU now comprises :- 1 x 100amp main switch + 3 x 6amp and 1 x 16 amp mcb's + 1 x 63amp 30ma RCD protecting 2 x 32amp and 1 x 45amp MCB's.
However my query is that the note on the CU states 'The Total load must not exceed the rating of the main switch ' which is 100amps and yet the total MCB amp rating adds up to 143 amps. Can anyone explain this anolamy in laymans terms please. Is there a formula for calculating the total load allowable in terms of fuse rating for any given main switch amp rating?
However my query is that the note on the CU states 'The Total load must not exceed the rating of the main switch ' which is 100amps and yet the total MCB amp rating adds up to 143 amps. Can anyone explain this anolamy in laymans terms please. Is there a formula for calculating the total load allowable in terms of fuse rating for any given main switch amp rating?