Electricians' tedious bickering

[FingRinal]

Can you tell us where in the OSG that it makes a distinction to rings and radials as regards spurs?

 

[xerxes]

Why are you assuming that it's a spur? We don't know, yet.

 

[ban-all-sheds]

Can you tell us where in the OSG that it makes a distinction to rings and radials as regards spurs?

I can't, because radials don't have spurs, only rings.

 

[FingRinal]

Oh dear oh dear....I'm afraid you are wrong. We are not talking about a lighting radial. We are talking about a socket final radial and standard circuit arrangements in the OSG using BS1363 accessories.

I suggest you read Appendix 8 of the OSG again, but this time more carefully...

Perhaps you could also read BS1363 whilst you at it...it may enlighten you.

 

[ban-all-sheds]

Perhaps you could read the definition of "spur" in BS7671.

And what does BS1363 have to do with circuit types? My copy says it's the "Specification for 13 A fused plugs and switched and unswitched socket-outlets", and does not contain any of the following words:

ring
radial
spur

 

[FingRinal]

How can I say this without causing offence to people on a DIY Forum? I'll try.

There is a lot more to electrical installation design than simply doing what everyone else does, following cheat sheet, reading a DIY book etc.

As good as BS7671 is, it is not an educational tool. Having limited knowledge is a good thing, so long as the limitations are not exceeded.

Long gone are the days when the Regs were a do this or do that publication. The OSG has to some extent replaced this.

If you wish to know more about this subject without going too deeply into engineering and science, perhaps you could post on the IET Forum what you think is correct and ask for clarification. If that doesn't satisfy you, come back to this thread and ask again. I may be able to dig out some noddy guides from several years ago that might help (if you really want to plumb the depths of engineering).

In the meantime, follow the OSG. It is there to offer relatively simple guidance. Follow accepted working practice and try to understand that unless you are a suitably qualified (Chartered) electrical engineer, the IET's publications shouldn't be dismissed without careful consideration.

 

[securespark]

Appx 8 does indeed make reference to spurs on both a ring or radial final circuit.

However, I believe it is very confusing: on a ring final, the idea is that non-fused spurs do not exceed the total number of outlets & permanently connected equipment. Further, those non-fused spurs can only feed one 1363 outlet each. This together with floor area limitations limits load on the circuit.

However, with a radial circuit, the whole circuit is effectively a chain of spurs from spurs (using their above definition). The circuit is limited more by floor area than anything else.

So the OSG seems to contradict itself, does it not?

 

[securespark]

Oops, sorry mod 11. Didn't see your comment until I had posted.

Perhaps you could cut & paste all of this into a separate thread?

 

[FingRinal]

I'm sure the IEE would have spotted it, if it were true. The advice in App. 8 is pretty clear. If there were an exception , the guidance would be explicit.

App. 8

General.

A ring or radial circuit, with spurs if any....

It doesn't define a different kind of spur for radial sockets. It refers to them both. It goes on to define a spur. It does not go on to define a ring spur and a radial spur.

It's very easy to pick out things the Regs, OSG etc. do not say, but it is important to focus on the things they do say. Don't look for smoke and mirrors, especially in the OSG. The OSG is intended to make things clearer, easier, better and not muddier, harder and worse. It is there to help and not hinder. It's the best guide there is.

 

[ban-all-sheds]

How can I say this without causing offence to people on a DIY Forum? I'll try.

I don't think that people are offended by your repeated attempts to make yourself look foolish, are they?

There is a lot more to electrical installation design than simply doing what everyone else does, following cheat sheet, reading a DIY book etc.

Or reading the OSG?

As good as BS7671 is, it is not an educational tool. Having limited knowledge is a good thing, so long as the limitations are not exceeded.

It is encouraging that you are starting to realise that.

Long gone are the days when the Regs were a do this or do that publication. The OSG has to some extent replaced this.

It is certainly a useful guide.

If you wish to know more about this subject without going too deeply into engineering and science, perhaps you could post on the IET Forum what you think is correct and ask for clarification. If that doesn't satisfy you, come back to this thread and ask again. I may be able to dig out some noddy guides from several years ago that might help (if you really want to plumb the depths of engineering).

Is this patronising tone meant to upset me, or make you look superior and clever, or make you look petty and foolish?

In the meantime, follow the OSG. It is there to offer relatively simple guidance. Follow accepted working practice and try to understand that unless you are a suitably qualified (Chartered) electrical engineer, the IET's publications shouldn't be dismissed without careful consideration.

Assume that I do know enough to understand your explanation of why an unfused branch from a radial circuit in the same sized cable, and therefore complying with 433-02-01 just like the rest of the circuit, needs to be limited to one socket etc.

And can you also explain why with Appendix 8 of the OSG, pp 151-153 which is about radials as well as ring finals, you have decided that the paragraph on spurs on p 153 applies to both circuit types even though that contradicts the definition of "spur" in BS7671, and not just to what actually count as spurs?

 

[ban-all-sheds]

Appx 8 does indeed make reference to spurs on both a ring or radial final circuit.

No, it makes reference to spurs in a section which deals with both rings and radials.

The definition in the regulations makes it quite clear that the term "spur" only applies to branches from rings.

However, I believe it is very confusing: on a ring final, the idea is that non-fused spurs do not exceed the total number of outlets & permanently connected equipment. Further, those non-fused spurs can only feed one 1363 outlet each. This together with floor area limitations limits load on the circuit.

It doesn't really, because with rings there's no limit on the number of sockets you can have*, and therefore no limit on the number of non-fused spurs*, and with radials there is no limit on the number of sockets you can have*, no matter how "branchy" or tree-like the circuit is.

* Except that eventually imposed by the amount of cable you need to connect all of the sockets together.

However, with a radial circuit, the whole circuit is effectively a chain of spurs from spurs (using their above definition).

No it's not, it's a radial final circuit. A spur is, according to their definition, a branch from a ring final circuit.

So the OSG seems to contradict itself, does it not?

Not at all.

 

[ban-all-sheds]

For radials or rings, only one non-fused spur per socket or junction box connected on the main circuit cable(s).

That is wrong.

A radial circuit may have any number of unfused branches of any length.

 

[Taylortwocities]

I'm going to refer to the Trades Description Act and determine if the subject title of this thread contravenes it

 

[ban-all-sheds]

I'm sure the IEE would have spotted it, if it were true. The advice in App. 8 is pretty clear. If there were an exception , the guidance would be explicit.

There doesn't need to be an exception, and the guidance is explicit.

It talks about spurs.

A spur is a branch from a ring final.

Therefore a branch from a radial final is not a spur, and the paragraph on spurs does not apply to branches from radials.

It doesn't define a different kind of spur for radial sockets. It refers to them both.

It does not define spur, and it does not define branch.

The Wiring Regulations define spur, and they say:

Spur. A branch from a ring final circuit.

Not "a branch from a final circuit".

Not "a branch from a ring or radial circuit".

Explicitly "a branch from a ring final circuit". There really can be no misunderstanding of that.

It goes on to define a spur. It does not go on to define a ring spur and a radial spur.

It does not define a spur. It does not repeat the definition of spur from the Wiring Regulations, nor does it invent a definition of a "radial spur".

It's very easy to pick out things the Regs, OSG etc. do not say, but it is important to focus on the things they do say. Don't look for smoke and mirrors, especially in the OSG. The OSG is intended to make things clearer, easier, better and not muddier, harder and worse. It is there to help and not hinder. It's the best guide there is.

In the introduction it says:

"This Guide is for electricians (skilled persons)..."

It probably (and reasonably, IMO) assumes that it's audience is skilled enough to have read and understood at least the basics of the Wiring Regulations, including the definitions of terms.

You could easily argue that the sentence "A ring or radial circuit, with spurs if any...." is badly written and would be better rearranged as "A radial or ring circuit, with spurs if any....", but it shouldn't really confuse anybody who understands the definition of "spur".

 

[Pensdown]

I'm going to refer to the Trades Description Act and determine if the subject title of this thread contravenes it