9" grinder trips 16amp MCB

The Wylex fuseboxes were either rated for the same in each way, with a maximum of 30A.
A few were made with one way suitable for higher current, 40A or 45A, and that was either located directly next to the main switch, or in a few it was an entirely separate one on the opposite side of the main switch (so you might have 6 circuits on the left of the main switch up to 30A each, and a separate 45A one on the right side of the switch.
The difference was the contacts themselves, the high rated being of different material and slightly different design. The busbar was the same throughout.

flameport said:

The Wylex fuseboxes were either rated for the same in each way, with a maximum of 30A. ... A few were made with one way suitable for higher current, 40A or 45A, and that was either located directly next to the main switch, or in a few it was an entirely separate one on the opposite side of the main switch ... The difference was the contacts themselves, the high rated being of different material and slightly different design.

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Yes, I've certainly seen (and owned) some of the former, but was not even aware of the existence of the latter.

flameport said:

... The busbar was the same throughout.

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Indeed, but if immediately adjacent to the Main Switch (left or right), the length of the bit of busbar servicing the high-rated fuse would be less than that servicing the other fuses.

Kind Regards, John

I’ve Got one of them wylex. With the separate high rated gang. Is it worth anything on eBay

EFLImpudence said:

If there were only one MCB would you put it on the left of the busbar?

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I've recently done one with switch on right and 8 RCBOs on the left - and 10 blanks in between. IMO it made sense to simply populate from the left. No point tryingbto group them as there'll be a few additions in the future.
Worst I've seen was my mates workshop. "Electrician" who wired the vehicle lift moved everything along to put the new breaker next to the main switch. But didn't move the neutrals or earths - and didn't change the labels either