Which solution-spur from cooker ring or 2 spurs from socket?

[jangcy]

Hello,
I was searching on this forum and others and I couldn’t find the right solution/advice.
My problem is that I would like to add spur in kitchen and not sue which option to choose.
There is picture below of current rings.

http://imageshack.us/photo/my-images/101/opt1.jpg
I would like to add one more socket above units (double one – I put single on picture)

As far as I know I CAN NOT add two spurs from one socket (however not sure what if one is fused – if somebody knows if there any different please let me know). In electrical regulation book I found that there could be just ONE UNFUSED spur from existing ring(socket)
So this option probably is not legal

http://imageshack.us/photo/my-images/854/opt1a.jpg

So I’ve this option (easier to do because of access)
(one spur from socket from kitchen ring circuit and one from cooker radial ring via switched FCU)
Not sure if I can use cooker ring or not-the socket for dishwasher won’t be use not-it’s just incase if in future we would like to get one

http://imageshack.us/photo/my-images/838/opt1b.jpg

And this option – get another junction box under worktop and get spur from it....(but as cabinets now fitted might be more difficult...

http://imageshack.us/photo/my-images/10/opt1c.jpg

Which one you would choose?

And some information about my circuits. It’s ALL protected by RCB (if right spelling) inside CU.

And now I’ve got other question about difference. As everyone said there CAN be just ONE spur from socket what would be the different between option 1 and option 2 apart from wiring complication in double socket (too many wires)

http://imageshack.us/photo/my-images/692/twooption.jpg


Thank you everyone.

 

[ban-all-sheds]

There is no difference - electrically you have 2 spurs from one socket, which you should not have because the potential for unbalanced loading of the ring is too high.

Coming off the cooker circuit is also a bad idea, as they are designed with the expectation of serving a cooker, which is not a fixed load (i.e. it uses a lot more power when first switched on than when it's up to temperature.

But looking at your sketch, it appears simple to put the FCU on the ring rather than making it a spur, and probably not too much effort to do the same with the new socket you want.

Points to note:

The horizontal socket circuit cables you show must not be buried in the wall, neither the new ones nor the existing ones.

All this work is notifiable.

 

[jangcy]

Hi
Thank you for reply.
So let remove cooker ring from it (not touching it)
Is actually Option 3 OK? Additional spur from ring via junction box behind oven (possible access) wouldn't over load circuit?
There is 5 sockets and 2 spurs (single spurs on all circuit at the moment.
PS
Yes all vertical cable are in channel or just attached to the wall under worktop - they are visible.
Picture below...

 

[Paul_C]

Electrically speaking in terms of loading on the ring cables, there's really little difference between option 1 and option 3. Given that the ring will be at least multiple tens of feet in length, moving the connection for your spurred socket from the existing socket to a junction box which is probably no more than 18 inches further around the ring, the difference it will make is negligible.

From the practical point of view, however, getting four 2.5 sq. mm T&E cables into the existing box would probably be a very tight squeeze, unless an unusually deep box has been used. The separate junction box, or rearranging the ring to pass through each accessory in turn would probably be easier in the long run.

I would also query the socket you already have earmarked as "dishwasher, washer etc." Is it a double socket which you intend to use for both appliances eventually? If so, then the arrangement from a single 13A FCU is not a good idea. If it's a single socket intended for one or the other appliance, that's different.

In electrical regulation book I found that there could be just ONE UNFUSED spur from existing ring(socket)

You may be getting mixed up with the requirement that a single unfused spur may feed only one single or double socket, and that the total number of points wired as spurs should not exceed the total number of points wired directly on the ring (i.e. that there should be no more than one spur socket for each ring socket). It doesn't preclude two separate spurs from being taken from the same point on the ring.

 

[diynoob]

Opt 4: Spur off the "dishwasher etc" socket. Whilst you shouldn't spur off a spur, it's legit to spur off a fused spur. You are of course limited by the 13A FCU, so this option is dependent on the planned load. If there is already a dishwasher and other appliances using that socket then maybe this option is a non starter.

Opt 5: Call an electrician. Since this is kitchen work I guess all options are notifiable so it's probably cheaper and less hassle to pay a part P certified electrician to do it.

 

[jangcy]

I would also query the socket you already have earmarked as "dishwasher, washer etc." Is it a double socket which you intend to use for both appliances eventually?

I'm sorry my mistake....it's just one appliance at one time (it was just sample)-it's single socket just for dishwasher OR washer - however might be never fitted.

You may be getting mixed up with the requirement that a single unfused spur may feed only one single or double socket, and that the total number of points wired as spurs should not exceed the total number of points wired directly on the ring (i.e. that there should be no more than one spur socket for each ring socket).

I'm aware of that

It doesn't preclude two separate spurs from being taken from the same point on the ring.

do you mean that?:

?
there is one more alternative as wires are still long enough to do switched FCU as part of ring circuit and then go to socket and then from socket do spur to next socket or fit junction box under worktop, like on picture below:

Opt 5: Call an electrician. Since this is kitchen work I guess all options are notifiable so it's probably cheaper and less hassle to pay a part P certified electrician to do it.

It might be option. But it's quicker to ask here then arrange with him to come...he's done part of job and now I'm doing kitchen and then he will come again to finish, but now I can see that additional socket would be helpful and it's still not to late to fit wires and make some more holes
or my wife will have live with current amount of sockets

 

[RF Lighting]

 

[ban-all-sheds]

Yes all vertical cable are in channel or just attached to the wall under worktop - they are visible.

It's not with the vertical ones where there is a problem with burying them, it's with the horizontal ones.

• http://www.voltimum.co.uk/files/gb/attachments/niu/l/attachments/c5-43.pdf
  
  
• http://web.archive.org/web/20061110111450/http://www.niceic.org.uk/downloads/concealedcables.pdf
  
  
• IEE article
  
  
• IEE Article on 17th Edition requirements for concealed cables.

 

[ban-all-sheds]

Opt 5: Call an electrician. Since this is kitchen work I guess all options are notifiable so it's probably cheaper and less hassle to pay a part P certified electrician to do it.

It might be option. But it's quicker to ask here then arrange with him to come...he's done part of job and now I'm doing kitchen and then he will come again to finish, but now I can see that additional socket would be helpful and it's still not to late to fit wires and make some more holes

That you gave that reply in response to the notification issue might mean that you think that because an electrician has done some of the work, and is going to come back and do more, that he'll be able to certify all of it, including your work.

He won't. He's not allowed to. It doesn't work like that.

If you make changes to anything he has done, or expect him to add to what you have done, he won't be able to sign anything off - it's all or nothing.

 

[ban-all-sheds]

It doesn't preclude two separate spurs from being taken from the same point on the ring.

True, the regulations do not explicitly preclude that.

you should not have (2 spurs from one socket) because the potential for unbalanced loading of the ring is too high.

 

[Paul_C]

you should not have (2 spurs from one socket) because the potential for unbalanced loading of the ring is too high.

The very nature of the ring is such that the current on each side of the point at which the load is connected will be unbalanced, except for a load connected at precisely the mid-point of the ring.

The difference between connecting an extra load at an existing box and one added at a point which is probably only about 18 inches away on the ring will be very small. For a ring which runs for a total length of 60 ft., for example, moving a 10A load a distance of 18 in. along the ring will result in an increase of 0.25A in one leg and a corresponding decrease of 0.25A in the other.

For most practical purposes, if the loads connected to two spurs run from the same point on the ring are high enough to result in an excessively high current flowing in the shorter leg of the ring, then the same two loads connected to the ring a mere foot or two apart are just as likely to result in the same problem. Just the same as if the loads were connected to adjacent sockets on the ring itself. It's an inherent shortcoming of the ring-final circuit as used in the U.K.

 

[jangcy]

Yes all vertical cable are in channel or just attached to the wall under worktop - they are visible.

It's not with the vertical ones where there is a problem with burying them, it's with the horizontal ones.

I'm sorry....my mistake...of course I was thinking about horizontal cables

That you gave that reply in response to the notification issue might mean that you think that because an electrician has done some of the work, and is going to come back and do more, that he'll be able to certify all of it, including your work.

He won't. He's not allowed to. It doesn't work like that.

If you make changes to anything he has done, or expect him to add to what you have done, he won't be able to sign anything off - it's all or nothing.

Yes....I've checked that as well....it was more to just fit cable under tiles so it's ready to be connected.
But with all that problem we decided to leave it as it is.....

Anyway I would like to say thank you to all who replied. Got much more information about UK regulations
(my brother who is electrician but not in UK explained me a little bit about cable resistance, length of circuit, max/min fuses, cable sizes but didn't want to suggest any option as he doesn’t know UK regulations....

Thank you!!

 

[ban-all-sheds]

The very nature of the ring is such that the current on each side of the point at which the load is connected will be unbalanced, except for a load connected at precisely the mid-point of the ring.

The difference between connecting an extra load at an existing box and one added at a point which is probably only about 18 inches away on the ring will be very small. For a ring which runs for a total length of 60 ft., for example, moving a 10A load a distance of 18 in. along the ring will result in an increase of 0.25A in one leg and a corresponding decrease of 0.25A in the other.

For most practical purposes, if the loads connected to two spurs run from the same point on the ring are high enough to result in an excessively high current flowing in the shorter leg of the ring, then the same two loads connected to the ring a mere foot or two apart are just as likely to result in the same problem. Just the same as if the loads were connected to adjacent sockets on the ring itself. It's an inherent shortcoming of the ring-final circuit as used in the U.K.

Yes - I know all that, and I agree that there's no significant difference between 2 spurs from a socket and 2 spurs, one from a socket and one from an almost adjacent JB.

They are both bad ideas.