John Rumm writes:

On 18/02/2013 18:18, Stephen H wrote:
On 16/02/2013 20:00, John Rumm wrote:

(In reality a 20A plate switch and a single 2.5mm T&E would have been
adequate (i.e. in effect creating a switched unfused spur)).

I did actually sit down and think this through from a good design point
of view...

As stated, there is a 2.5mm2 ring main with a 32A RCBO.

snip

Ah, right I see the line of thought you are following. In fact you are
over worrying since this exact scenario has already been thought about
in the design of unfused spurs...

snip

There is nothing dangerous about what you propose, although its over
egging things a tad. Lots of design effort over the years has gone
into make sure that these things work well in reality, and while there
are theoretical weaknesses in the designs of unfused spurs, they prove
time and again in practice to be very robust and reliable.

I'm pinning this reply in my newsreader as I've never seen it explained
so clearly before. Perhaps this Q&A is also worth sticking on the Wiki
somewhere?

Alex

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