13 Amp socket tolerances

[geoff]

Well I could tell you but I'd have to kill you

just a minute, that's the wrong way around

[geoff]

In message , "dennis@home" writes

Que?

Have you turned spanish on us

... or are you going to blame that on your spellchecker?

[geoff]

Why else do you think that they sectioned him in sheltered accommodation with padded walls and plastic utensils?

[geoff]

In message , "dennis@home" writes

When and where dennis?

You're not actually qualified to do such things, are you?

[polygonum]

Anyone remember Green Acres with Eva Gabor?

[dennis]

Well as people slowly adopt the more modern circuit designs that are in the regs it will become less of an issue, but I fail to see why you want to stick with the old stuff which will be dropped from some future issue of the regs. Its not as though what I say isn't in the regs, it is it just hasn't been in there for as long as rings and has been added by chartered engineers wishing to address the short comings of what is in there..

They are unrelated.. its not like the railways where there is limited cash to spend on safety and that they waste it on the wrong safety gear. Its just a case of adopting the more modern circuit designs in the regulations rather than the old fashioned rings.

Please try and be consistent.. earlier you were dismissing misuse of appliances. You had to to make the ring safe.

Rubbish, its in the regs and should be done to the regs. However some bits of the regs are to cover old stuff that was done with different compromises.

Nothing I have said contravenes those regs, just exceeds them at minimal, if any, costs.

You can continue to promote the old compromises if you like, however you do so at the disregard of peoples safety. Sure it was safe enough in the '60s but why not improve on it like the IET want you to? You can tell the IET want you to as there are more restrictions on how big a ring can be than on a modern radial BTW.

[ARWadsworth]

You're not doing bad for someone who said he was not going to bother arguing.

[Old Codger]

"Modern energy efficient" lights for instance. Now they really are a hazard, to the elderly at least.

[John Rumm]

Ring circuits tend to be used rather more often than less these days, probably as they are so well suited to modern usage patterns. In the past it was not uncommon to have houses with only a single ring circuit (and for space heating to be run from it as well). Now many houses have three or more serving different load and usage patterns.

As insulation levels in new homes improves, it is entirely possible that guidance to installers on using unfused spurs will be increased. However I expect ring usage in general to gain in popularity due to its greater flexibility for diverse power provision, its better performance under many fault conditions, and its higher earthing integrity (of particular relevance with the ever increasing use of SMPSUs and hence risks of higher earth leakage currents).

I don't believe that is true. I think you will find that radial circuits pre-date rings.

I wonder if you actually think about some of the statements you make? I think you will find that there *is* limited cash to spend on electrical installations. Whether its a builder attempting to maximise profit, or an end user seeking the best improvement in protection and convenience for their not unlimited budget.

When the ring is frequently the most appropriate circuit choice, this makes no sense.

No, the message is quite simple. If you want to improve electrical safety, stop prattling on about things that do not cause problems, and focus on those that do.

I don't recall being consulted.

I don't recall anyone suggesting otherwise. However that does not answer the point; that by following your suggestion you will be devoting more of your budget to implementing things that have very limited or no practical benefit, rather than things with tangible and easily demonstrated benefits.

Well at least you now acknowledge that all circuit designs are compromises. (such is any design)

As I pointed out elsewhere, it is easy to think of scenarios where you can apply overloads to your preferred circuits, that would be in reality more likely occur accidentally, yet you single these out as a weakness of ring circuits. That makes no sense to me.

In one breath you claim to be "exceeding" the regs, and then you claim to be complying with them. Yet you fail to explain why the problem you cite elsewhere (long term overload) is not equally appropriate to a radial circuit.

Consider a 28A overload on radial protected by a 20A MCB on cable that may only have Iz of 21A, or 46A load on a 32A MCB protecting a 4.0mm^2 with an Iz of only (say) 34A. Changing circuit topologies does not make these problems go away. Your "exceeding the regs" solution does not fix them either (in fact it makes some of them more likely). As a designer you need to implement the same protection mechanism (and others) that provides overload protection for the spur cable on the ring - i.e. exercise judgement, analyse likely usage, and make sensible predictions based on your analysis. Decide whether that is an appropriate place to use a spur or not, and if so, what cable to use.

Remember prevention of long term moderate overload is a responsibility of the designer, and not the user.

You are welcome to your opinion, but I don't accept that, and I also suspect that the majority of those with an understanding of the issues would not either.

Your conclusion seems to be based entirely on your prejudices, rather actual evidence.

[geoff]

In message , ARWadsworth writes

Certainly seems to be incapable of doing the decent thing and apologising when he's been proved to be wrong

Like claiming that my email address was munged ...

[Old Codger]

Radial circuits were the norm before the modern ring was introduced. The only thing modern about current socketed radials is that they use the 13A sockets. In fact the radial circuit never dies out. They ran alongside ring mains for higher power appliances, cookers, hobs, immersion heaters.

I do not believe the regs require you to use oversize cable or undersized MCBs.

The regs specify what is required for today's installations. "Old stuff" does not have to comply with today's regulations. A change that comes to mind is the installation earth. This was changed when the use of plastic pipes negated earthing to the incoming water main. Where copper mains are still in existence, as in my property, there is no requirement to change the earthing method.

Over sizing cables costs money, quite significant money for a whole house.

Rubbish

Ring mains are still safe. If problems do occur it is because they have a given maximum load which may not be enough for some folk. However, unless electricity becomes cheap, and it never has yet and I doubt it will in the foreseeable future, I can't see many folk using many high power portable appliances simultaneously for long periods in a domestic environment so the ring main, particularly if houses have more than one, will continue to be perfectly adequate at a cheaper price than radial circuits.

Are you suggesting a radial circuit can have more sockets than a ring main?

[dennis]

Well that's good. You now realise that you can't just have a set of don't for the user and that you need to design a safe circuit. So the first step would be to replace the 32A breaker with a 20A breaker as you are only using a single 2.5 mm2 cable.

[John Rumm]

Indeed.

This would be correct, however its a moot point since a circuit using a single 2.5mm^2 cable and a 32A MCB is not a standard one.

(The configuration might however be allowable under certain very restrictive conditions)

[charles]

Interestingly - in our theatre - built 12 years ago and everything "tested" was found, during a routine inspection, to have two spurs coupled to a single 32A MCB. The documentation stated that a ring circuit was installed. Luckily there was space on the distribution board for another breaker of the relevant phase - which has now been installed - my me. Not cheap since its a MCBO rather than a simple breaker. (Local Authority requirement for theatres)

[ARWadsworth]

dennise thinks that ring circuits are old!

They don't. Just because you can understand the regs does not mean that dennise can.

With no benefit to anyone but the copper suppliers.

It's dennis, what do you expect?

dennises suggestions are the ramblings of a failed middle/lower manager who was forced out of his job because he was a useless wanker.

[ARWadsworth]

You would not be the first person to have this happen to them. One regular poster to this group found a plastered over socket backbox on his house and had two radials not a ring!

One of the reasons installers do proper testing and keep records is to prove that their work was up to standard.

[Andy Wade]

There's nothing to prevent a radial circuit branching at its origin though, providing it meets all relevant requirements.

[ARWadsworth]

But there is no regulation to leave two live coiled up cables behind the plaster inside a metal backbox!!

[charles]

[Snip]

this installation was done by a firm who were members of the ECA and an NIC EIC approved contractor. It's not the first fault found. In the kitchen a ring had the neutral missing between two boxes (this being an all conduit installation) Supposedly this was properly tested -I could even locate the test certificates if I bothered to look..

[geoff]

But ....

he programmed an ASIC