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RCBO boards: freedom, at a priceWhy not an RCBO on every circuit?
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The simple board (main switch plus a busbar) can take CBs or RCBOs in any mix, and comes in 5-way, 10-way, 12-way and much bigger sizes. These "RCBO boards" are now very popular.
- The benefit: each circuit that needs RCD protection gets its own RCD. In a house, the downstairs sockets and downstairs lights both need 30 mA protection. If something plugged into a socket trips its RCBO, only that circuit goes off and the lights stay on.
- The cost: the enclosure is simple, but you pay for an RCBO on every circuit.
Our example: a three-bedroom house
Circuits needing 30 mA RCD protection: 1 downstairs socket ring final 2 upstairs socket ring final 3 kitchen ring final 4 downstairs lighting 5 upstairs lighting 6 cooker circuit (cooker switch with a socket on it) 7 shower (room containing a bath or shower) = 7 circuits, all needing 30 mA → 7 RCBOs, plus a spare or two
That's where the cheaper, long-established alternative comes in: the split-load board.
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- Building Regs
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