I'd prefer the solution of doing away with ring finals.
CHESTNUT
- Thread starter ebee
- Start date
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I'm confused. The argument you are presenting would mean that, with some provisos, it is OK to have a short (<3m) radial circuit supplying a single double socket, wired in 2.5mm² cable(installation method A/100/102), or even 1.5mm² if 'clipped direct', protected by a 32A (or even 50A) MCB, on the basis that the double socket 'cannot' represent more than a 20A load, and that the combined In of the fuses in associated plugs 'cannot' exceed 20A. Do you think that "every single electrician who has signed an EIC/MWC/EIC/EICR since 1946" would agree with that?
What do others think?
Kind Regards, John.
The same problem would arise with a 4mm² 32A radial. The problem would only go away if 'double 13A sockets' which could not safely handly 2 x 13A loads were to be banned. In the meantime, Bernard's solution would be the only foolproof one.
Kind Regards, John.
Of course then we get onto the fact that BS1363 does not require socket doublers to be fused....
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If they don't then they should not be signing off installations which have spurs etc like that, should they.
The accessory problem would remain, but all of the circuit protection ones would disappear.
That's what I'd be interested to hear from those in question....
... so folks, what you you think about a radial circuit supplying just one double socket, 2.8m in length, run in 1.5mm² cable (clipped direct) protected by a 50A MCB? Is everyone happy that such an arrangement is compliant and 'satisfactory'?
Kind Regards, John.
Agreed. However, Bernard's comment/suggestion presumably related to the 'accessory problem', since use of two single sockets rather than one double would (a) be non-compliant in the situation we've been discussing and (b) would actually kill your argument about circuit protection (since there would then be no doubt that we were talking about an Ib and 'total In' of 26A, not 20A).
Kind Regards, John
H
holmslaw
..
The 200A fuse (or 20,000A, come to that!) would be OK for BAS's argument, but the 1mm² cable would not be, since, per his theory, it would be protected by fuses with 20A's worth of In at t'other end - but, yes, it would seem that 1.5mm² cable supplied directly from Henleys on the meter tails might satisfy him!Bas must be happy with that because he doesn't understand 433.2.2.Why not a 200A fuse and 1mm if you believe BAS's bizarre interpretations.
Kind Regards, John.
Can you show that 1.5mm² is afforded fault protection by the service fuse?
And can you also show that it counts as good workmanship (no, I am not interested in the pedantry of trying to deparate design and erection), given that it has strayed quite some distance from a 2.5mm² spur/radial on a 32A breaker.
BTW - you should ignore the b******s from holmslaw about me not understanding 433.2.2 - read his body of work on this issue:
//search.diynot.com/forum_sear...0&author=holmslaw&search=Search+Forum&stype=0
and you'll see that I'm not the only one who "doesn't understand it". On the basis of his previous observations it wouldn't be particularly far-fetched to conclude that he thinks nobody else in the world understands it but him.
And can you also show that it counts as good workmanship (no, I am not interested in the pedantry of trying to deparate design and erection), given that it has strayed quite some distance from a 2.5mm² spur/radial on a 32A breaker.
BTW - you should ignore the b******s from holmslaw about me not understanding 433.2.2 - read his body of work on this issue:
//search.diynot.com/forum_sear...0&author=holmslaw&search=Search+Forum&stype=0
and you'll see that I'm not the only one who "doesn't understand it". On the basis of his previous observations it wouldn't be particularly far-fetched to conclude that he thinks nobody else in the world understands it but him.
Can you show that 1.5mm² is afforded fault protection by a 50A MCB?- or are you assuming that an RCD is present in the circuit?
Kind Regards, John.
No, but nor can I show that it is not.
i.e. I have not done the calculations.
TBH, I have not done them for 2.5mm² on a 30/32A device either - I'm assuming that given 433.2/.3/434 and the fact that spurs like that are permitted, someone has.
Not much use with a L-N fault.
That makes two of us, then - but you seemed previously to be happy to assume that it would be OK with 2.5mm².
Never assume
You may be right - but, if so, the someone must have made assumptions about PFC and PSCC, so the answer could not be 'generic'.Kind Regards, John.
LookGang,
when I started this post my intention was to show that under the correct circumstances the dear old ring final was deemed both safe and compliant.
Under those same circumstances spurs are allowed anywhere on a ring i.e. wired directly to a point or somewhere else on the ring or indeed at the fuseway.
I have previously found some people think at the fuseway is a No No for some reason best known to them.
I have also found that some that find a spur from the fusway and a ring from that same fuseway perfectly safe seem to think that removal of the ring suddenly makes the spur a radial on its own 32A MCB therefore unsafe for some reason.
similarly the number of points on the ring may be ignored because we rely on floorspace and length of conductors to be kept to sensible limits along with consideration of amb temp insulation etc then purely from a point of view of the number of radials (spurs) connected at the fuseway does not cause us the same problem as more than one spur at any other place on the ring because the current drawn at the fuseway would be the same for that particular ring as it would if was run as several radials to the same points instead on a one to one basis.
I don`t think any of us would like to see a circuit with one twin socket in 2.5 T & E on a 32A MCB cos it don`t look right.
Similarly non of us would like to see several radials, each with one twin socket connected to one fuseway even if the fuseway could comfortably accept that number of conductors , again it would not look right.
But both of those examples are no more or less onerous than the bog standard ring final that we do accept. All of the same considerations do or do not apply equally.
when I started this post my intention was to show that under the correct circumstances the dear old ring final was deemed both safe and compliant.
Under those same circumstances spurs are allowed anywhere on a ring i.e. wired directly to a point or somewhere else on the ring or indeed at the fuseway.
I have previously found some people think at the fuseway is a No No for some reason best known to them.
I have also found that some that find a spur from the fusway and a ring from that same fuseway perfectly safe seem to think that removal of the ring suddenly makes the spur a radial on its own 32A MCB therefore unsafe for some reason.
similarly the number of points on the ring may be ignored because we rely on floorspace and length of conductors to be kept to sensible limits along with consideration of amb temp insulation etc then purely from a point of view of the number of radials (spurs) connected at the fuseway does not cause us the same problem as more than one spur at any other place on the ring because the current drawn at the fuseway would be the same for that particular ring as it would if was run as several radials to the same points instead on a one to one basis.
I don`t think any of us would like to see a circuit with one twin socket in 2.5 T & E on a 32A MCB cos it don`t look right.
Similarly non of us would like to see several radials, each with one twin socket connected to one fuseway even if the fuseway could comfortably accept that number of conductors , again it would not look right.
But both of those examples are no more or less onerous than the bog standard ring final that we do accept. All of the same considerations do or do not apply equally.
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