Electricians' tedious bickering

[Softus]

What's a branch?

 

[ban-all-sheds]

If they've spurred the conservatory off the existing ring but protected it all with a 13A fused spur first, then it's fine as this 13A fuse prevents the cables being overloaded.

If the original circuit is a radial, same thing goes as it should be protected at the CU by a 20A device anyway, as long as it doesn't exceed maximum cable length.

If they've just spurred off the ring with no protection for the additional points, then there is a risk of the cables being overloaded as the main protective device would be 32A at the CU.

If, as I think, your second sentence is saying that an unfused branch from a radial is OK because the branch will be properly protected at the CU, and your 3rd sentence is saying that the reason you need to fuse a branch from a ring is that it won't be properly protected at the CU, can you have a go at explaining it to FR?

 

[Softus]

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

Interesting.

 

[fleming'slefthandrule]

A spur is defined in part 2 of the regs as a branch cable from a ring final circuit. (P.202 Basic Electrical Installation Work, T.Linsley).

 

[Pensdown]

To throw a spanner in the works - 17th definition, Spur - A branch from a ring or radial final circuit.........so to act as referee...BAS is right....but not for long

 

[ban-all-sheds]

Can't wait to see if the 17th OSG demands an FCU for spurs from radials then...

 

[Softus]

Can't wait to see if the 17th OSG demands an FCU for spurs from radials then...

The OSG can't, and doesn't, "demand". It's a guide.

 

[FingRinal]

BAS, rather than go blue in the face proving that something hasn't been said or hasn't been written, perhaps you could point us to anywhere where it states that there IS a distinction. Or perhaps point us to anywhere which explicitly describes your version of events.

 

[oharaf]

If I could just throw my inexperience into the ring here......

Surely, if we are thinking about 'future' proofing all the time, any spur from a ring final would be placed after an FCU so that in the "future" further sockets may be added

If I have read this correctly, what FR was talking about was, possibly, where there is an existing Radial, some one may wish to 'spur' off from a socket that is not at the end of the Radial.

Again in this case, surely for pure over kill again but, also some 'future' proofing an FCU should be added.

I must say in most cases I am still really struggling to think why anyone would fit a radial over a ring final.

Perhaps one solution here may be to make it a statutory requirement that all houses have an "Electrical Suitability" survey every 10 years and that major works are enforced following this!!!!!!!!!!!!!!!!!111

Plenty of work for us all then chaps!!!

Nice discussion, I have picked up my OSG to read this bit, 16th Ed. OSG, from my reading it does not make a distinction from spurs on Ring Final or radial, just points out the need to use FCU if more than one socket is to be added..

Now you can all assasinate me...then I will learn some more

 

[FingRinal]

Oharaf,

adding a socket to the end of a radial would be an extension of the circuit. A spur would be a connection at a point on the main circuit to connect another socket/ FCU. Having connected such a spur to a new socket, you cannot then spur from this socket to another socket according to the OSG and 'accepted' standards of good practice.

 

[ban-all-sheds]

BAS, rather than go blue in the face proving that something hasn't been said or hasn't been written, perhaps you could point us to anywhere where it states that there IS a distinction. Or perhaps point us to anywhere which explicitly describes your version of events.

I've done that already.

I'll do it again.

The definition of "spur" is explicit and unambiguous in the Wiring Regulations.

Therefore when the OSG talks about spurs it talks about them as defined in the Wiring Regulations.

Therefore that paragraph in the OSG, which refers to spurs, cannot also refer to branches from radial circuits, because branches from radial sockets are not spurs.

 

[ban-all-sheds]

If I have read this correctly, what FR was talking about was, possibly, where there is an existing Radial, some one may wish to 'spur' off from a socket that is not at the end of the Radial.

What if they want to add two sockets to the end of the radial?

Again in this case, surely for pure over kill again but, also some 'future' proofing an FCU should be added.

It is clear why FCUs are needed if a spur has more than one socket on it.

Can you explain why an FCU is needed on a branch from a radial that has more than one socket?

I must say in most cases I am still really struggling to think why anyone would fit a radial over a ring final.

That's a separate debate.

Nice discussion, I have picked up my OSG to read this bit, 16th Ed. OSG, from my reading it does not make a distinction from spurs on Ring Final or radial, just points out the need to use FCU if more than one socket is to be added..

It does not need to make a distinction. It talks about spurs. Spurs are by definition branches from ring finals, not radials, therefore the section on spurs is not talking about branches from radials.

 

[oharaf]

Hi BAS

point 1. isn't adding say 2 sockets to the end of a radial just extending the radial?

I fully agree with you spurs are really only relevant to RF circuits and yes no distinction is made

 

[oharaf]

Oh thanks, you have now cleared up some confusion in my understanding;

You CAN 'branch off' from a radial without FCU protection, but to 'branch off' a RF you MAY need to add an FCU if adding more than one socket, therefore a 'branch' does not exist as such on RF circuits as they are defined(ish) as a spur!!

Is I reading you right???

 

[FingRinal]

BAS, you are wrong. That's all there is to it.

Two sockets at the end of radial would be two extensions.

If, as you say, a spur is only defined for a ring, why are you using this terminology to refer to radials? Show me where it allows multiple branches on SOCKET radials as you describe.

You are wrong in what you say. Very wrong. I'd sort out the obvious and elementary defects in your own electical installtion before advising others of your ill conceived and erroneous interpretation of current standards and practice.