spurs

steve 111 · Mar 10, 2017

what is maximum amount of spur sockets taken from a main , the main amperage can be changed easily the wiring is 2.5 and a ring main is not possible without a lot of work as this is a large old house which has been wired this way , there will only be one large consumer a water heater .

telectrix · Mar 10, 2017

you can take only 1 outlet as a spur from a ring final unless you fit a 13A FCU

Dave OCD · Mar 10, 2017

I'm sorry I think you need to word your question a bit better, or it might just be me.

Resu · Mar 10, 2017

Dave OCD said:
I'm sorry I think you need to word your question a bit better, or it might just be me.

Not just you!

telectrix · Mar 10, 2017

i got confused when he didn't mention john wayne (spurs).

Dave OCD · Mar 10, 2017

Better to mention Spurs than Arsenal at the moment.

telectrix · Mar 10, 2017

Arse who?

Pete999 · Mar 11, 2017

steve 111 said:
what is maximum amount of spur sockets taken from a main , the main amperage can be changed easily the wiring is 2.5 and a ring main is not possible without a lot of work as this is a large old house which has been wired this way , there will only be one large consumer a water heater .

1 spur per socket on the RFC See Appendix 15 BS 7671

ChrisElectrical88 · Mar 11, 2017

As many as you see to be sensible with a 4mm twin and earth spurring off? I could be wrong, I'm not going to the van at this time for the BYB.

Octopus · Mar 11, 2017

ChrisElectrical88 said:
As many as you see to be sensible with a 4mm twin and earth spurring off? I could be wrong, I'm not going to the van at this time for the BYB.

Wrong!

Pete999 · Mar 11, 2017

Murdoch said:
Wrong!

What he said ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ring final circuits and radials - - Yahoo Image Search Results - https://images.search.yahoo.com/yhs/search?p=ring+final+circuits+and+radials&fr=yhs-mozilla-102&hspart=mozilla&hsimp=yhs-102&imgurl=http%3A%2F%2Felectrical-engineering-portal.com%2Fwp-content%2Fuploads%2F2016%2F10%2Fconsumer-unit-ring-final-circuit-ver-2.png#id=2&iurl=http%3A%2F%2Fi69.photobucket.com%2Falbums%2Fi62%2FRFLighting%2FIMGP2837.jpg&action=click

telectrix · Mar 11, 2017

what he said about what he above said ^^^^^. although 4mm is capable of handling the current in itself, adding several outlets to the same point on the rfc could overload the 2.5mm rfc cable especially if the point was close to one end of the rfc.

ChrisElectrical88 · Mar 11, 2017

Ignore me then. Thank you for correcting me fellas.

HandySparks · Mar 11, 2017

Pete999 said:
1 spur per socket on the RFC See Appendix 15 BS 7671

There's no limit on the number of spurs on a ring. But not more than one accessory is allowed on any unfused spur.

Richard Burns · Mar 11, 2017

If you have a ring final circuit then the recommendation is that the number of unfused spurs does not exceed the number of point on the ring. e.g. with ten sockets of the ring a maximum of 10 unfused spurs is recommended. The number of fused spurs is unlimited.
An unfused spur will only supply a single point of use.
In practice you would be looking at the ring loading and ensuring that there were not a concentration of current drawn at one point of the ring.

HandySparks · Mar 11, 2017

Richard Burns said:
If you have a ring final circuit then the recommendation is that the number of unfused spurs does not exceed the number of point on the ring. e.g. with ten sockets of the ring a maximum of 10 unfused spurs is recommended. The number of fused spurs is unlimited.

I'm clearly missing something here, as both you and Pete999 have mentioned this. I can't find anything in the current edition of the regs about a limit on number of spurs, although maybe I've read it in a previous edition.

Pete999 · Mar 11, 2017

HandySparks said:
I'm clearly missing something here, as both you and Pete999 have mentioned this. I can't find anything in the current edition of the regs about a limit on number of spurs, although maybe I've read it in a previous edition.

Have you looked at Appendix 15 in the BYB

Richard Burns · Mar 11, 2017

HandySparks said:
I'm clearly missing something here, as both you and Pete999 have mentioned this. I can't find anything in the current edition of the regs about a limit on number of spurs, although maybe I've read it in a previous edition.

As I say it is a recommendation not a regulation.
It is mentioned in the OSG under standard circuits.

SparkyChick · Mar 11, 2017

Having re-read the OP, I'm not sure we're talking about a ring....

"what is maximum amount of spur sockets taken from a main , the main amperage can be changed easily the wiring is 2.5 and a ring main is not possible without a lot of work as this is a large old house which has been wired this way"

I think he's talking radial.

HandySparks · Mar 11, 2017

Pete999 said:
Have you looked at Appendix 15 in the BYB

Yes. Can you tell me where in Appendix 15 this is referred to?

HandySparks · Mar 11, 2017

Richard Burns said:
As I say it is a recommendation not a regulation.
It is mentioned in the OSG under standard circuits.

Thanks. Can't find my OSG at present.

I have found it in the 15th edition, Appendix 5, paragraph heading "Spurs".

HandySparks · Mar 11, 2017

HandySparks said:
Thanks. Can't find my OSG at present.

I have found it in the 15th edition, Appendix 5, paragraph heading "Spurs".

Just found my OSG. Yes, 7.2.2, still retains this clause. Looks like it's out of step with the current regs.

Richard Burns · Mar 11, 2017

SparkyChick said:
Having re-read the OP, I'm not sure we're talking about a ring....

"what is maximum amount of spur sockets taken from a main , the main amperage can be changed easily the wiring is 2.5 and a ring main is not possible without a lot of work as this is a large old house which has been wired this way"

I think he's talking radial.

Interesting you could well be right. With main I assumed ring main.
If it is a radial then spurs are not possible, only branches, which are also unlimited though again recommended to be minimised (I think).
A 20A radial could be run all over the place without overloading a 2.5/1.5 mm² cable, though a large house circuit may experience nuisance tripping.

Richard Burns · Mar 11, 2017

HandySparks said:
Thanks. Can't find my OSG at present.

I have found it in the 15th edition, Appendix 5, paragraph heading "Spurs".

I did not know that!

Pete999 · Mar 11, 2017

HandySparks said:
Yes. Can you tell me where in Appendix 15 this is referred to?

Between App 14 and App 16 Sorry couldn't resist Page 453 in my copy

Pete999 · Mar 11, 2017

HandySparks said:
Yes. Can you tell me where in Appendix 15 this is referred to?

Sorry mate I misread your post, off hand no I can't but it's not a very big appendix 3 or 4 pages most of the appendix is diagrams

Pete999 · Mar 11, 2017

HandySparks said:
Yes. Can you tell me where in Appendix 15 this is referred to?

Or On Site Guide: 7.2.2

Pete999 · Mar 11, 2017

HandySparks said:
Just found my OSG. Yes, 7.2.2, still retains this clause. Looks like it's out of step with the current regs.

Why?

HandySparks · Mar 11, 2017

Pete999 said:
Sorry mate I misread your post, off hand no I can't but it's not a very big appendix 3 or 4 pages most of the appendix is diagrams

Appendix 15 is two pages. One on rings and one on radials. There's no reference to number of spurs off a ring.

Pete999 · Mar 11, 2017

HandySparks said:
Appendix 15 is two pages. One on rings and one on radials. There's no reference to number of spurs off a ring.

You are correct it doesn't, but the OSG is what it is a guide BS7671 is a regulation and imo if someone is in doubt about something, the OSG is where to go and look.

Currently reading: spurs

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