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Patrick Olner
 
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Default MCB discrimination and size?

I've just run 6mm SWA from the consumer unit in the house to a
workshop some 25m away. The workshop has 4 circuits - 2 lighting and 2
smallish ringmains, run in 2.5mm. The SWA from the house will feed a 4
way CU in the workshop via a separate RCD - my questions a

1. What size MCB needs to be fitted to the 6mm SWA in the house CU -
32a or 40a?
2. What size MCB needs to be fitted in the workshop's CU - 32a for the
ring and 6a for the lights?
3. How do I avoid the lack of discrimination caused by running 2 MCB's
in line - ideas include i, using type C's in the workshop or ii,
discrimination will be provided by having 40a MCB in the house and 32a
in the workshop or iii fitting traditional fuses in the workshop,
rather than MCB's

Am I on the right wavelength? Any guidance/advice/tips or suggestions
wll be lapped up... thanks everyone for a great NG
cheers, Patrick