On 31/10/17 23:29, Peter Humphrey wrote: > On Tue, 31 Oct 2017 17:33:53 +0000 > Wols Lists <antli...@youngman.org.uk> wrote: > >> In the UK at least also, we have ring mains. These are rated at 30 Amps, >> from which you can take a 13 Amp feed from any socket. Once you start >> taking power over multiple leads the wiring has more resistance, plugs >> introduce resistance, etc, and the voltage can drop rapidly. > > I've never seen that, nor heard of it. It sounds like a major fire risk too, > which the wiring regs would never countenance.
Sorry, no, I meant plugging one extension lead into another ... exactly what you are NOT supposed to do. > >> (It is mandatory, according to code, if you hard-wire a feed off a ring >> you must separate it with a 16 Amp fuse.) > > I don't recognise that either. It sounds like a special case to me. And > where do I buy a 16A fuse? > Well, I've got several scattered over my house ... and my father-in-law has at least one in his fuse box! You would have thought it was easy to take a spur off of a socket that's part of a ring main, but believe me, as an amateur sparky it's NOT! They sell special points - often with a switch - to take a feed off a ring, and they all have a - mandatory - 16Amp fuse. Or they might take a standard 13Amp fuse. My father-in-law has a spur coming off his fuse box, and that has a 16Amp fuse or circuit breaker, rather than the standard 30Amp. I did a bit of wiring for him ages ago, and when I saw it, my immediate reaction was "what the heck's that!" and I refused to touch it until I'd worked out what was going on - very sensible advice with electric! >> I've never seen one, but I would have thought a motor/generator pair >> with a hefty flywheel would provide very good surge/spike/whatever >> protection, and provide nice clean power. Plus, it would be unlikely to >> burn out if you had to provide protection from several big consecutive >> shocks, like a lightning strike. > > Just think of the noise though, and the expense. > Why should it be noisy, or expensive? Okay, you're turning electrical energy into kinetic and back again, but a computer draws typically 2Amps max. A box like that to provide clean power shouldn't be too bad. (Actually, using something like that as the PSU to step down to 12V or 5V might be a good idea in areas of dirty power ... :-) Cheers, Wol
