My own experience is completely at odds with that, though I have little in domestic environments.
Do Away With Ring Final Circuits?
- Thread starter securespark
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My own experience is completely at odds with that, though I have little in domestic environments.
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Me neither commercial/industrial are my fields
True - but, for new circuits (or when re-wiring), and as you go on to imply, only because people are seemingly 'obsessed' with 2.5mm² cable. In term of Zs and VD, 4mm² is 'almost as good as 5mm² (2 x 2.5mm²) - and, for what it's worth, I personally find 4mm² cable nicer/easier to work with than 2.5mm².
For reasons I've often discussed, I would personally rarely consider installing a 20A radial.
Kind Regards, John
Yes, as I often say, 'CPC redundancy' seems to be the one (and I think probably 'only') thing to be said in favour of ring finals.
However, if that is one 'pro', there is a corresponding 'con' - that if there is an 'unrecognised break' in the L or N of the ring, that can theoretically result in cable being overloaded (and/or Zs becoming 'too high' if it's the L conductor) without anyone being aware of the problem.
Kind Regards, John
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Probably only 'fractionally' - in the right circumstances, 120V is plenty high enough to kill, and being 'apparently safer' (than 230/240V) may result in a degree of foolish complacency.
Kind Regards, John
Plus of course - a radial is not simply one line of cable.
Numerous unfused spurs with more than one socket can be installed (plus afterthoughts at a later date) such that a single 25m. limit (if that is what the figure is) to meet Zs maximum can easily add up to considerably more than 25m. with none of the hassle of a ring circuit meandering to - and from - all points.
Numerous unfused spurs with more than one socket can be installed (plus afterthoughts at a later date) such that a single 25m. limit (if that is what the figure is) to meet Zs maximum can easily add up to considerably more than 25m. with none of the hassle of a ring circuit meandering to - and from - all points.
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Indeed - certainly not necessarily.
Indeed so.
Furthermore, the 'maximum cable length' figures so often quoted by eric are potentially misleaading. Assuming is figures are correct, they seem to indicate that one can have a about 4 times the cable length with a ring as compared with a radial (106m vs. 25m with his figures). However, that is only because that 'length' includes the return to the CU - and actually means that the furthest a socket can be from the CU (as the cable flies') on a ring is 53m. That's double (not 4 times) the length for the corresponding radial, which is hardly surprising given that, as far as a socket in the middle of the ring, it is being supplied by two identical cables in parallel.
Put another way, if one wired a radial literally with two 2.5mm² cables in parallel throughout the circuit ( a situation approached by using 1 x 4mm² cable), the furthest socket could still be 53m (as the cable flies') from the CU - exactly the same as with a 2.5mm² ring.
Hence, I would suggest that the difference is far less dramatic than eric always implies.
Kind Regards, John
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The USA spec house I lived in this country has both UK mains ring and USA socket outlets
The 110volt sockets are supplied via a 20Amp transformer centre tapped to earth. The idea being the appliances over 1KW used the 240v ring and the low load stuff used 110v outlets. The house was originally installed with 240v for 'fridge, dishwasher, washing machine all behind the appliances and 1 outlet over the worktop; the rest of the house had 1 outlet in the lounge and 1 on the landing. The kitchen had 4x110 outlets, the lounge another 4 doubles and the bedrooms 2 doubles per room. We didn't bother with a wiring upgrade for several years - biggest hassle was finding 110v bulbs in this country for portable lights.
The house we had in the States all the high current appliances were permanently wired to 220v mains and the 110v outlets supplied by a transformer.
I do think the 110v outlets and portable household electric 'toys' is the most sensible thing the USA does and I'd support the same in the country.
Intuitively, that sounds like good sense.
However, somewhat surprisingly, it seem that there are only around a couple of dozen domestic electrocutions per year in the UK - which is equivalent to around 3-4 days worth of UK road deaths or (at current crazy levels, which the government seems to be 'accepting'!) 3-4 hours worth of Covid-19 deaths,
Particularly because some (maybe 'a good few') of the domestic UK electrocutions might well have occurred even if the supply voltage were 110V/120V, there is therefore very little scope for reducing that figure substantially - and I would imagine far too little scope to persuade people that the massive effort and cost involved in changing all domestic UK sockets circuits (and 'portable household toys') to the lower voltage would be justified. I would imagine that the same amount of effort and money directed in other directions could probably result in far more deaths being avoided.
Kind Regards, John
So let's improve the standard of workmanship and do it properly. And for heavens sake let's do away with the idiot 'electricians' who constanly post their rubbish on social media too.
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In which case it's not USA spec
Until last year they were 'legal' in the whole of EU.
One of the idiots on YT seems to think so and seems to make it a 'chestnut' of his.
Glad to see I'm not the only one to call it 2 phase.
You should already know you're not the only one - as well as myself, you also have BS7671 as company
...Kind Regards, John
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