12-02-2015, 08:48 AM
"Live and neutral go into a single consumer unit with a two pole rcbo followed by per-circuit mcbs...., i.e. if it trips, the workshop goes dark."
I rather doubt it's a RCBO. Almost certainly an RCD. These are also marked with a current rating but that's purely a maximum current it's allowed to pass. There's no overcurrent or short circuit trip. This sort of arrangment, RCD as main switch followed by MCBs, was common until outlawed by the 17th ed regs. It was a low cost way of meeting 16th ed regs and was sometimes used in the days of 15th ed. I never liked it, preferring to protect those circuits that needed RCDs with individual RCDs or RCBOs.
I rather doubt it's a RCBO. Almost certainly an RCD. These are also marked with a current rating but that's purely a maximum current it's allowed to pass. There's no overcurrent or short circuit trip. This sort of arrangment, RCD as main switch followed by MCBs, was common until outlawed by the 17th ed regs. It was a low cost way of meeting 16th ed regs and was sometimes used in the days of 15th ed. I never liked it, preferring to protect those circuits that needed RCDs with individual RCDs or RCBOs.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
