Correct. Back “in the day” the bus bars in the old fuseboxes were not as big and the advice from manufacturers was to use the higher fuses nearest the main switch.
Is that irrespective of which side the Main Switch is?
Is that really true? Although it is certainly true that that was the manufacturers' advice (indeed ones like the Wylex Standard would only 'allow fuses >30A to be installed adjacent to the main switch, those were the days in which they were over-engineered (and 'beautifully engineered) - and I suspect that the bus bar of, for example, a Wylex one would put modern ones to shame!
True - but, mind you, there are other sort-of-related things that the manufacturers do currently 'stipulate' which I strongly suspect most people ignore (even if they are aware of them). For example (as we have discussed in the past, Wylex say of their MCBs ..
I think that statement, or a similar one, has actually been in their technical documentation for decades. The extract I posted came from a 2007 document, which is the oldest I can currently find.
Same in my youth (and same comment about mine
).
There's not really any material difference between 'highest on the right' and 'lowest on the left', is there?
Not when completed, but they would be fitted 'from the right'.
Then the question is why the main switch was on the right.
Why?
Well, it had to be somewhere (left, right, or 'in between') - maybe they tossed a coin! Mind you, I suppose that 'in the middle' would have minimised busbar path lengths, but they don't seem to have thought of that!
Yes, I am replying to myself.
Logic.
Then with so little thinking, why was it deemed necessary to 'teach' lowest rated MCB on the left?
You have the Neutral to get past.
Probably not. I confess that I've been thinking about a 'fully (or nearly fully) populated' fusebox/CU/
I think I've already covered that. If, having tossed a coin (or whatever), they decided to put the Main Switch on the right, they might have felt that it was best to have 'highest-rated on the right' - which, in a fully-populated box would be the same as 'lowest on the right'.
It would certainly not be beyond the wit of man to get around that issue - for example, the L busbar could "detour around' the neutral connection.
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