Dedicated thread for Rrodd and his question on ring circuit wiring

[sparkwright]

I gather Rrodd was disappointed that he felt his thread was not getting enough relevant replies to his questions.

So, here is a new thread for Rrodd to ask whatever he likes.

It would be helpful if Rrodd could relay some info mentioned in the other thread, to refresh our minds.

There were things mentioned in the other thread that were there to help Rrodd, such as a comment about NOT spurring, but EXTENDING the ring, so each accessory has two cables supplying it. I can only assume Rrodd did not read this, as he didn't comment on it either way.

There may have been confusion about spurring off a socket TWICE. This could mean either:
1) Spurring from a socket already wired directly to the ring to a new point, and the running a cable from the new point to a second new point. This is not permitted on a ring circuit, UNLESS the first new piece of cable is 4mm2 minimum.
2) Spurring TWO cables from a socket already wired directly on the ring - so that existing socket would have FOUR cables at it. This arrangement is ok by the regs - but you won't see it in a DIY book or similar (most books other than the regs seem to state you can only spur once (ie three cables at the socket). This may be why you may have thought you couldn't have four cables.

You also mentioned something about running a short length of cable in SWA. SWA can be a bit fiddly for some people, and it has to be done correctly with glands, the armour needs to be earthed. Are you OK with this?

As for 'irrelevant garbage' - I think that's something school teachers specialise in.

And yes, most of us here are old enough to know what happens when you 'assume' something, because when you assume, you make an ASS out of U and ME.

 

[Taylortwocities]

This one will run and run. I have a bucket of popcorn here.

 

[JohnW2]

I'm not sure whether one can invoke "I'm out" before one is "in", but that's what I am

Kind Regards, John

 

[ericmark]

The IET published this, which goes a long way to explaining the ring final.

I must admit I think the idea of not doing some thing because some one in the future may asume and not test seems flawed, the idea of extending a ring final is included in this, however the cheap £50 plug in tester with loop often will not test down to 1.38Ω and testers to measure ohms using 250 mA or loop impedance down to 1.38Ω are expensive. If one is worried about volt drop then even lower.

The figure of 106 meters is quoted for the maximum length of 2.5 mm² ring final, which it seems is calculated considering 20 amp load in centre and 12 amp even spread, however there seems to be nothing in the regulations to say this is how to work it out.

When doing my C&G 2391 we were told to test for figure of eight, but not seen any rule which is broken if we do have a figure of eight, other than

The load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable (Regulation 433.1.5 refers). This can generally be achieved by:
(i) locating socket-outlets to provide reasonable sharing of the load around the ring
(ii) not supplying immersion heaters, comprehensive electric space heating or loads of a similar profile frog the ring circuit
(iii) connecting cookers, ovens and hobs with a rated power exceeding 2 kW on their own dedicated radial circuit
(iv) taking account of the total floor area being served. (Historically, limit of 100 m² has been adopted.)

I will admit to my mind food and laundry does not mix, although tradition is we used the same room, but either for food preparation or laundry but not both together, and the twin tub would be dragged into the centre of the floor, so it was portable, and although the load may have been 3 kW, nothing else was used at the same time.

However in the last house the washing machine and tumble drier would be running in back ground while food was prepared, and even in this house although we have a utility room, it is supplied by same ring final, but a good distance from the consumer unit, so load is reasonably central.

Seen dedicated supplies for the immersion heater, but rare for the tumble drier, but today with heat pump models there is no longer any real problem.

 

[Taylortwocities]