Date   : Sun, 13 Sep 2009 20:37:07 +0100
From   : philb@... (Phil Blundell)
Subject: Leccy @ Acorn World '09

On Sun, 2009-09-13 at 11:25 +0100, Mick Champion wrote:
> True. It makes having fused plugs rather pointless don't you think? Most 
> people I know will reach for the nearest fuse whatever it's value to 
> replace a dud.

Fusing at 13A in the plug is still rather better than relying solely on
the circuit fuse, which would obviously be 30A for a typical ring
circuit.  This was the reason that the BS1363 plug was invented in the
first place: although it had been considered OK to rely on the circuit
fuse for protection when 15A radial circuits were the norm, the idea of
having a small flex protected by nothing more than the 30A fuse on a
ring main was obviously a bit too much.

> Yes. This is quite a good thing until it comes a time the consumer needs 
> to change the fuse.

Well, at least in that situation they have the rating on the old fuse to
use as a guideline.  It doesn't seem all that hopeless to expect that
people will manage to replace a blown fuse with one of the same rating
(and/or same colour, which in most domestic situations is going to give
you the right result in 99% of cases).

> That is a good argument. I'll go with that. Next time I end up in the 
> Questors theatre in Ealing, I shall have a closer look at their wiring 
> arrangements with interest. Once again I do wonder why we have fuses in 
> our plugs. While nobody could argue it's another form of protection if 
> the correct fuse is installed, but Europe and the US of A don't bother. 
> I wonder if any other nation uses fused plugs.

Europe and the USA don't, in general, place their outlets on circuits
rated at more than about 15A.

There are several other nations that use BS1363 plugs, though I can't
think of any that use fused plugs of a different design.

> > It's certainly true that the general trend has been to harmonise the
> > regs with the rest of Europe as far as possible.  For example the 17th
> > edition also introduced mandatory RCD protection for all sockets, which
> > has been standard in Europe for a while but wasn't previously required
> > here.
>
> I presume the RCD would be installed at the consumer unit rather than 
> one built into the socket?

Generally yes, it would be in the consumer unit.  The regs don't mandate
this specifically, but providing a single RCD to protect the whole
circuit would obviously be cheaper than providing local RCDs at every
socket-outlet.  Also, the new regulations require the circuit cable
itself to be RCD-protected under some circumstances (eg when buried in
cable without mechanical protection) and obviously this requires the RCD
to be situated upstream of the cable in question.

p.