Published: 28 November 2007
Category: News
Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, about a distribution board main switch rating calculation, is answered by SELECT:
Question: Let´s say we have a distribution board having four MCBs - two 30A units for ring CCTs and two 6A units for lighting. How do we calculate the main switch rating? Do we follow the rule of the maximum demand?
Answer: The rating of the main switch will fundamentally be determined by the rating of the protective device supplying the distribution board, i.e., the distributor's cut-out fuse. The short-circuit capacity of the device should also be not less than the prospective short circuit current.
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