Washing machine fused spur... can I also run a microwave from the same socket?

[EFLImpudence]

Concentrating load at a point on a ring can therefore be a problem if that point is not close to the center of the ring.

You cannot argue against the principles of something by saying someone might do it wrongly.

The same could be said of sockets on a ring circuit or, indeed, electricity in houses.

 

[JohnW2]

You cannot argue against the principles of something by saying someone might do it wrongly. The same could be said of sockets on a ring circuit or, indeed, electricity in houses.

Indeed.

Those who express concerns about various aspects of spurs from ring finals very rarely express (or maybe even have) the corresponding concerns about the positioning of sockets on a ring final. That is particularly true of those who (incorrectly) claim that two (or more, if physically practicable) spurs originating from the same point on a ring is 'not allowed', but regard it as acceptable if to have spurs originating from sockets (or whatever) that are only a few inches apart.

Kind Regards, John

 

[LondonLad21]

That really is not a very helpful statement. Just one double socket is theoretically enough to 'overload' a 13A fuse. As for "diversity calcs", they are essentially impossible for a sockets circuit, unless the designer has a crystal ball.

The whole point of allowing fused spurs (with an 'unlimited' number of sockets) is that the 2.5mm², or maybe 1.5mm², cable will then be adequately protected. Those who cannot think beyond what examples are shown in Appendices to the regs don't seem to understand that, from the point-of-view of cable protection, there's nothing wrong with an unfused spur (from a ring final) supplying multiple sockets if it's wired with 4mm² cable.

Kind Regards, John

You're correct, that isn't helpful without the clarification that I mean socket (singular, not double) and that more than one socket could be added from many points of the ring to add a collective of single sockets served by its' own single spur.

There is a degree of reasonable probability on diversity, eg, a centrally heated, well maintained property would have little expectation of an array of fan heaters or high load items being placed in every room so as to exceed the rated load of the ring. I say reasonable, in that of course there are circumstances and can not be planned for. Hence generally refraining from spurring off the ring as it just makes for risk in future.

 

[JohnW2]

There is a degree of reasonable probability on diversity, eg, a centrally heated, well maintained property would have little expectation of an array of fan heaters or high load items being placed in every room so as to exceed the rated load of the ring. I say reasonable, in that of course there are circumstances and can not be planned for.

Sure - whether one calls it 'diversity', 'common sense', 'guesswork' or whatever.

In fact, in such a house, even if one had just one 32A ring supplying the whole house (including kitchen), with literally dozens of sockets scattered throughout the house (including some on unfused spurs, even multiple ones on 4mm² spurs), I suspect that the probability of the current in any of the cables ever being "likely to exceed for long periods the current-carrying capacity of the cable" (the avoidance of which is all the regs ask of a ring final) is probably very low.

Hence generally refraining from spurring off the ring as it just makes for risk in future.

Particularly given the above, that's the bit which, in practice, I don't think is necessarily valid. In particular, I don't really understand those who have a problem with spurs, but not with adding sockets to a ring. If a designer creates potential problem, it is because of the number of sockets, the areas the sockets serve and where they connect to the ring (either directly or as spurs) - and that's just as much an issue for sockets 'on the ring' for as ones which are on spurs from the ring.

Kind Regards, John