Can i spur more then once with bigger cable?

[tomodo]

Hi guys working in a factory having to spur off a ring main problem is its already got a fuse spur coming off it for some fans. The ring main is on a 32A breaker and wired in 4mm guessing this might be for volt drop. Question is can i spur off this socket twice using 4mm cable? Then the cabel is protected and safe still. so i can get wires in terminals was thinking to relocate fused spur for fans into new added socket. so it will go RING MAIN spured to new socket then out of there to fused spur. All wired in 4mm. cheers

 

[Darkwood]

Rather than explain it all its easier to view the diagram in appendix 15 page 453 of the new BYB or page 425 BGB.

 

[Pete999]

Yep Appendix 15

 

[Charlie_]

Go for it! No problem at all in doing what you have proposed.
No need to refer to the dummies guide for RFCs

 

[Pete999]

Go for it! No problem at all in doing what you have proposed.
No need to refer to the dummies guide for RFCs

You what? who's the dummy?

 

[tomodo]

Is that in the on site guide?

 

[Andy78]

Go for it! No problem at all in doing what you have proposed.
No need to refer to the dummies guide for RFCs

However it might be beneficial for someone unclear on a subject to read and research the available guidance rather than just to "go for it" on the say so of someone on the internet.

 

[Andy78]

Is that in the on site guide?

In the regulations, Appx 15.

 

[Pete999]

In the regulations, Appx 15.

Sounds like the op doesn't have the BYB

 

[Charlie_]

I find it strange that so many qualified electricians need so many guides to tell them exactly what to do..
How would you cope if there wasn't so many step by step set of instructions?
I feel that based on my observations that anybody with the ability to read could quite easily be an electrician..
Refer to the dummies guide on RFCs what does it say with regards to this situation?

 

[Pete999]

I find it strange that so many qualified electricians need so many guides to tell them exactly what to do..
How would you cope if there wasn't so many step by step set of instructions?
I feel that based on my observations that anybody with the ability to read could quite easily be an electrician..
Refer to the dummies guide on RFCs what does it say with regards to this situation?

So you know it all do you?

 

[tazz]

Charlie...When an op asks questions, most members do not need the regs book to answer it correctly. But they will quote the relevant section to aid the op with their reply. This is encouraged on the forum to prevent false or incorrect information being given.

 

[Charlie_]

That's a fair point Tazz but on this occasion what the op has been referred to is not relevent..
Also a lot of the time certain members are not helpful, frequently very rude..
Just quoting a reg number or something from the dummies guide is not being helpful, why not give advice substantiated with relevent regs, etc

 

[tomodo]

sorry but i havent got a copy of the regs... could someone post what appendix 15 says would be very grateful cheers.

 

[davesparks]

Is it not possible to just extend the ring main?

 

[tomodo]

be alot of hassle it goes right up to the ceiling which is about 20 metres high

 

[Sparkie30]

tried to post that page for you but for some reason cant

 

[Pete999]

That's a fair point Tazz but on this occasion what the op has been referred to is not relevent..
Also a lot of the time certain members are not helpful, frequently very rude..
Just quoting a reg number or something from the dummies guide is not being helpful, why not give advice substantiated with relevent regs, etc

I take it Charlie you are having a dig at me as one of the members who suggested the OP looks at App15 for details of how to wire spurs Ring finals and Radial finals, I believe the OP is an Electrician or a trainee I'm not sure,either way he ought to have access to the BYB or the OSG, I can't see, or understand your comment "not helpful just quoting regs etc" well I assure I was being helpful, rather than quote lines and line of text it would, in my opinion be for more helpful to the OP if he could look up the relevant information for himself, there I'm out:rant:

 

[tomodo]

anyone know how i can upload a picture ?

 

[Darkwood]

tried to post that page for you but for some reason cant

You wouldn't be allowed anyway its copyright material and would be removed straight away ... with a PM to warn you as well.

 

[tomodo]

from my computer

 

[tomodo]

View image: CCF12022015 00000

 

[tomodo]

I think this seems okay ? what do you guys think? ^^^^^^^

 

[Charlie_]

I'm not trying trying to have a pop at you personally..
I'm just making a general observation of how things seem to be, no offence intended..
Just seems so strange how so many are reliant on guides, etc for such basic information..

 

[Sparkie30]

You wouldn't be allowed anyway its copyright material and would be removed straight away ... with a PM to warn you as well.

oops forgot all about copyright thing. Thanks

 

[tomodo]

the radial circuit is the one im adding to it

 

[tomodo]

View image: CCF12022015 00000

Please have a look you have to scroll down

 

[Charlie_]

Your doodle gets the thumbs up from me
apart from it looks as though a six year old has drawn it.. Wink wink

 

[tomodo]

haha yeah my writing / drawing isnt the neatest

 

[HappyHippyDad]

This has been discussed a few times and some seem to find it acceptable to spur off a ring main with 4mm so that you can have more than one spur. Their reasoning is that it is safe because it is protected by a 32A MCB.

I dont feel very comfortable with this and would never do it, my reasoning being that it is a ring, not a radial. If you create a radial off of a ring then you could well be unbalancing it. Plus if someone sees a 4mm radial they may add to it at a later stage, unbalancing the ring even more.

If you are taking a 4mm cable from one socket to the next then I cant see why you couldn't just extend the ring which I think would be the best option.

I haven't got my BS7671 to hand, but I'm pretty sure it doesn't mention spurring off a ring in 4mm.

 

[davesparks]

It is a departure from the standard ring circuit, which doesn't necessarily mean it is wrong but does need a bit more thinking about.

 

[tomodo]

hmmmmm

 

[andyb]

I think HHD is right.
Can you not put the fused spur at beginning of the spur from the ring?

 

[Silly Sausage]

hmmmmm

The FCU is 13A max, so the proposed circuit spur is essentially a triple socket outlet.
I would say it's fine.

(App 15 is 'Informative' only. Other circuit layouts are available!)

 

[shanky887614]

be alot of hassle it goes right up to the ceiling which is about 20 metres high

? cut and joint

 

[Pete999]

The FCU is 13A max, so the proposed circuit spur is essentially a triple socket outlet.
I would say it's fine.

(App 15 is 'Informative' only. Other circuit layouts are available!)

Whereabouts are these other circuit layouts described?

 

[Silly Sausage]

Whereabouts are these other circuit layouts described?

In my brain after applying some thought

 

[Pete999]

In my brain after applying some thought

Yes BS 7671 is an informative document, but if we go on deviating just because we "gave it some thought" and thought we were right and someone got hurt because we thought it was alright, where would we stand in a court of law, "well your honour I thought it would be OK"

 

[Silly Sausage]

'They' are just 'standard' circuits.
Some guys on here have lights on rings or octopus/spider circuits or god help us, Neutrals at the switches!
They are all equally valid. As long they fulfil the Chapter 4 design criteria, all is well in the world!

 

[GEOFF S]

The onsite guide is not for comercial installations.

So im taking a different footing here, the ring circuit design in the onsite guide is for the purpose of a domestic single phase system amongst other prerequisites. So the installed ring is the design of someone? You need to prove it meets the requiremnts of BS7671. Specifically 433.1.103 plus the other general requirements.

Cheers

 

[davesparks]

The onsite guide is not for comercial installations.

So im taking a different footing here, the ring circuit design in the onsite guide is for the purpose of a domestic single phase system amongst other prerequisites. So the installed ring is the design of someone? You need to prove it meets the requiremnts of BS7671. Specifically 433.1.103 plus the other general requirements.

Cheers

I thought we were talking about the ring circuit design in bs7671 not the idiots guide?

 

[GEOFF S]

I thought we were talking about the ring circuit design in bs7671 not the idiots guide?

Where is this ring design?

Cheers

 

[davesparks]

Where is this ring design?

Cheers

Read the whole thread, the answer is in post 2, appendix 15.

 

[GEOFF S]

Read the whole thread, the answer is in post 2, appendix 15.

Dave, thats not a ring circuit design, its sets out the special regulation 433.1.103, that asisde its down to the deisgner to meet all the other general requirements.

Cheers

 

[davesparks]

Dave, thats not a ring circuit design, its sets out the special regulation 433.1.103, that asisde its down to the deisgner to meet all the other general requirements.

Cheers

I've not got the book in front of me but I thought that was where there is a full page illustration of the standard ring final circuit with spurs etc clearly illustrated.

 

[GEOFF S]

I've not got the book in front of me but I thought that was where there is a full page illustration of the standard ring final circuit with spurs etc clearly illustrated.

Yes it shows you a typical arrangement, no design spec. The standard circuits in the onsite guide have prerequsites set out, if these are not met then you need to design the circuit and show compliance.

Cheers

 

[Charlie_]

Also that little diagram is based on the ring being wired in 2.5.
In this case as initially explained the ring is wired in 4mm with a proposed 4mm spur

 

[shanky887614]

i wouldn't just guess its 4mm based on vd.

we were laughing at the way overspeced supplies on some jobs.

they were told your not allowed to use anything smaller than 4mm XD

it was for little smoke damper boxes controlling an individual smoke damper.

another personal favorite was a 70mm supply to a panel that only had 50a isolator

 

[davesparks]

Also that little diagram is based on the ring being wired in 2.5.
In this case as initially explained the ring is wired in 4mm with a proposed 4mm spur

Without further information we have to assume a worst case scenario that 4mm has been used due to de-rating factors making the ccc of 2.5mm too low for a ring. So without further information we cannot assume that the 4mm when de-rated has only got the ccc of the 2.5 in the standard circuit.