With reference to 433.1.204 and cable as installed has min capacity of 20A if protected by a 30A or 32A. If the protective device is reduced to 20A how is the new minimum as installed capacity calculated or arrived at ? I've been looking in the Electrical Installation Design Guide, but the answer is avoiding my eyes.
Well, I have done my sums and things are not so bad after all.
Ring is about 40 m long in total. Drier is plated at 2850 W; let's assume that the washing machine is the same, so 25 A total. 39/40 of the load goes the short way = 24 A.
RM B - plastic trunking so CCC = 23 A. There is another ring and a couple of lighting circuits flopping around in there so derate by 80% = 18.4 A.
Is this a problem? No because the overload is only of short duration. Phew - glad that's sorted! ?
Well, I have done my sums and things are not so bad after all.
Ring is about 40 m long in total. Drier is plated at 2850 W; let's assume that the washing machine is the same, so 25 A total. 39/40 of the load goes the short way = 24 A.
RM B - plastic trunking so CCC = 23 A. There is another ring and a couple of lighting circuits flopping around in there so derate by 80% = 18.4 A.
Is this a problem? No because the overload is only of short duration. Phew - glad that's sorted! ?
