Ring not a ring

[plugwash]

Rings and spurs are wired in 2.5mm cable. A ring has 2 paths back to the fuse or MCB whereas a spur only has one between itself and the ring so the total load is limited.

While I think daftpunk was being an asshole saying somethign was wrong without explaining why I do have some issues with this statement. it's mostly true but also quite misleading to the uninitiated.

Rings and spurs are wired in 2.5mm cable.

The requirement is for the cable to be able to safely carry 20A. What cable size is needed for this depends on cable tpe and installation conditions. 2.5mm is typical but it can be lower (MICC) or higher (thermal insulation, grouping factors etc)

A ring has 2 paths back to the fuse or MCB whereas a spur only has one between itself and the ring so the total load is limited

The general principle is that overload protection must be provided unless overloads are considered unlikely.

The thing with an unfused spur is that there is no protection from overloads in the fixed wiring. So the regs only allow one single or double socket. Presumablly the assumption is that the two sides of a double socket are unlikely to be heavilly loaded at the same time.

Whereas with a fused spur or a radial circuit with the correct breaker there is overload protection in the fixed wiring, and therefore no need to set a limit on the number of scokets.

The regs are somewhat inconsistent though in that multiple sockets clustered at the end of the ting are very nearly as bad electrically as multiple sockets on a spur. Yet the latter is explicitly prohibited while the former is not.

 

[JohnW2]

The regs are somewhat inconsistent though in that multiple sockets clustered at the end of the ting are very nearly as bad electrically as multiple sockets on a spur. Yet the latter is explicitly prohibited while the former is not.

Very true, but I would say that it's actually far 'worse' than you imply ...

... all it takes is for 32A of load to be 'on one side of the ring' and no more than three-quarters of the way from the CU to the mid-point of the ring (cable-length-wise) for the current in at least some parts of the cable to exceed 20A - and that's far from being 'clustered at one end'.

Kind Regards, John

 

[ban-all-sheds]

Stay off my threads!

I don't know how annoying or disappointing you will find this, and quite frankly I could not care less:

You do not have the right to decide who will or will not post in topics you start. That's the way that fora like this work. If you don't want the public joining in your conversations, don't hold them in public.

 

[ban-all-sheds]

Yes, the way in which he usually does it certainly is extremely annoying, as well as probably being counter-productive and probably being detrimental to the forum in general.

Done appropriately, his message (which, as you say, is often 'right') might sometimes get through - rather than just provoking a reaction to the language and style, rather than the content, of what he writes!

So you can provide a logical, reasoned explanation of what was wrong with the language and style of this:

Are you and you employer familiar with your duties and responsibilities in the Electricity At Work Regulations, and with the terms & conditions in the tenancy agreement and all the insurances?

can you?

 

[bandejapaisa]

Stay off my threads!

I don't know how annoying or disappointing you will find this, and quite frankly I could not care less:

You do not have the right to decide who will or will not post in topics you start. That's the way that fora like this work. If you don't want the public joining in your conversations, don't hold them in public.

You're a nob.

 

[ban-all-sheds]

Are you and you employer familiar with your duties and responsibilities in the Electricity At Work Regulations, and with the terms & conditions in the tenancy agreement and all the insurances?

Yes thank you.

Fair enough.

I was concerned not about your competence, only whether you have sufficient formal proof of it to allow you or your employer to claim that you or he had taken all reasonable steps and exercised all due diligence to ensure that you possess the knowledge or experience, or are under such degree of supervision as may be appropriate having regard to the nature of the work, necessary to prevent danger or injury.

 

[bernardgreen]

Are you and you employer familiar with your duties and responsibilities in the Electricity At Work Regulations, and with the terms & conditions in the tenancy agreement and all the insurances?can you?

Fpr a landlord the requirement is to have the electrical system maintained so that it complies with the required safety legislation in force at the time. Almost all landlords who achieve that requirement do so by employing a suitable electrician

I fail to see how Electricity At Work Regulations can be applied to a domestic residence unless the tenant is running a business from the property in which case the tenant is then responsible for compliance with Electricity At Work Regulations. and the landlord is responsible for the safety of general installation.

 

[ban-all-sheds]

The regs are somewhat inconsistent though in that multiple sockets clustered at the end of the ting are very nearly as bad electrically as multiple sockets on a spur. Yet the latter is explicitly prohibited while the former is not.

The former is, from the POV of it giving rise to danger:

Such circuits are deemed to meet the requirements of Regulation 433.1.1 if the current-carrying capacity (Iz) of the cable is not less than 20 A and if, under the intended conditions of use, the load current in any part of the circuit is unlikely to exceed for long periods the current-carrying capacity (Iz) of the cable.

 

[ban-all-sheds]

I fail to see how Electricity At Work Regulations can be applied to a domestic residence unless the tenant is running a business from the property in which case the tenant is then responsible for compliance with Electricity At Work Regulations. and the landlord is responsible for the safety of general installation.

At work I took some wiring out of our server room when I rebuilt it and sorted out the electrics.

 

[bernardgreen]

If the regulations were written in a way that banned sockets being cluster at the far end ( midpoint ) or any other point on the ring then they would include something like.

The minimum cable length between sockets shall be no less than X metres where X = L / N ( total length of ring divided by number of sockets ).

There would need to be a tolerance on X as enforcing equal cable lengths between sockets would be impractical for sensible positioning of sockets.

 

[bernardgreen]

At work I took some wiring out of our server room when I rebuilt it and sorted out the electrics.

Simon was not the original poster so your comments are not answering or advising the original poster

 

[ban-all-sheds]

Indeed they were not, but they were quite clearly neither directed at him nor presented as an answer to any of his questions.

 

[JohnW2]

The regs are somewhat inconsistent though in that multiple sockets clustered at the end of the ting are very nearly as bad electrically as multiple sockets on a spur. Yet the latter is explicitly prohibited while the former is not.

The former is, from the POV of it giving rise to danger: Such circuits are deemed to meet the requirements of Regulation 433.1.1 if the current-carrying capacity (Iz) of the cable is not less than 20 A and if, under the intended conditions of use, the load current in any part of the circuit is unlikely to exceed for long periods the current-carrying capacity (Iz) of the cable.

As I wrote last night, I don't think that really 'works', since it would be rare for a designer to be particularly confident that such a situation was "unlikley"...

As I implied, all it takes is for there to me two or more double sockets on one 'side' of the ring that are less than 75% of the cable distance from CU to midpoint of ring (something which I imagine is true of the great majority of ring finals) for there to be a possibility of current exceeding 20A 'in some part of the circuit'.

Kind Regards, John

 

[JohnW2]

If the regulations were written in a way that banned sockets being cluster at the far end ( midpoint ) or any other point on the ring then they would include something like. The minimum cable length between sockets shall be no less than X metres where X = L / N ( total length of ring divided by number of sockets ). There would need to be a tolerance on X as enforcing equal cable lengths between sockets would be impractical for sensible positioning of sockets.

See what I've just written in response to BAS - any such system would be effectively unworkable in the vast majority of situations. It would be very easy to 'overload' some of the cable of almost any real-world ring final if one really wanted to!

A saving grace is, of course, is that significantly large and prolonged 'overloads' are probably pretty unlikely, and I very much doubt that 32A is ever going to do any significant harm to 2.5mm² cable!

Kind Regards, John

 

[SimonH2]

I was concerned not about your competence, only whether you have sufficient formal proof of it to allow you or your employer to claim that you or he had taken all reasonable steps and exercised all due diligence to ensure that you possess the knowledge or experience, or are under such degree of supervision as may be appropriate having regard to the nature of the work, necessary to prevent danger or injury.

More likely - you just can't resist sticking your nose in at every opportunity. If you really were concerned about safety as you claim, you'd take heed of the advice you've had from many people in here about the way you express yourself - specifically about how to express yourself in a positive way which gets the safety message across, rather than your usual way which gets anything you say ignored as (as the OP put it) you make yourself look like a knob.

I fail to see how Electricity At Work Regulations can be applied to a domestic residence unless the tenant is running a business from the property in which case the tenant is then responsible for compliance with Electricity At Work Regulations. and the landlord is responsible for the safety of general installation.

The bit BAS was sticking his nose in was a reference to work I'd been doing at work, so yes H&SAW would apply. All above board.