Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, about consumer units in application and their internal arrangements, is answered by SELECT:
However, there is no main switch to isolate the complete board, as the tails from the meter are connected to the top of the first D/P RCD, then loop - from the live side of that RCD - to the next D/P RCD main switch.
As Regulation 537.1.4 of BS 7671: 2008 states: 'A main linked switch or linked circuit-breaker shall be provided as near as practicable to the origin of every installation as a means of switching the supply on load as a means of isolation', would the above scenario be acceptable, as there is not one overall main double-pole switch?
Answer: A double pole RCD as the type you describe can be used as a main switch, as it meets the requirements of a disconnector. You would need to have appropriate warning isolation notices affixed, as there is no main switch to isolate complete board.
It is unusual to find this type of arrangement, apart from when two separate consumer units are installed, or when off-peak is used in the same consumer unit. Can two sets of tails be connected into RCD live side without giving tails a 'haircut'? If so, this should be commented on.
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