Adding extra sockets to a ring

[SteveCav]

I am going to add a few extra sockets to a ring main and would like to confirm the correct method of doing this before commencing.

I currently have a study, which has only 1 double socket in it. One socket feeds a RCD extension lead to which appliances are plugged into and the other feeds another RCD extension lead to which appliances are plugged into via a passthrough homeplug.

I've had this setup for many years but am unhappy with the use of extension leads full stop.

I have 11 appliances to connect, consisting of: -

1 screen, 2 PCs, 2 Servers, 1 router, 1 switch, 1 Vodafone Sure Signal box, a cordless telephone and another homeplug in the extension (soon to be removed).

My main problem is that I wish to avoid the Servers undergoing an uncontrolled shutdown due to a power cut. In order to achieve this I was planning to add a UPS purely for the 2 Servers to allow them to shutdown in a controlled manner if a power cut occurs.

However, as everyone knows the UPS would need to go direct into a mains socket, not an extension and consequently I would then be left with no alternative but to use an extension into the other mains socket followed by an extension lead off this extension lead and I'm not going to do that!

Currently the existing socket is directly under the Consumer unit, so presumably is the first socket on the ring.

I was planning on connecting as follows: -

Assuming a feed from the consumer unit direct to the first socket (cable A) and a feed from the socket to the next socket in the ring (cable B) and knowing that the next existing socket in the ring is not in the same room which is the best way to connect into the ring?

Would I take cable B and wire into a JB (30Amp) and connect the new sockets (in series ) into that and then connect the last socket to another JB (30Amp) along with cable B?

Also, as these sockets are on an outside wall what is the best way to create the hole for the back plates? I know you can drill around the outside and chisel out but is there an easier method? Can I hire a tool for the job?

I am sure I can run the cables horizontally from socket to socket, can anyone confirm?

Any help appreciated
Steve

 

[Chri5]

If you are unable to break the ring at two separate sockets and create a ring extension between the existing sockets you can extend a ring from one socket.

Remove one of the cables at the socket, connect 1 x TE 2.5mm on the cable removed and take that to the number socket (and then in and out of all the new sockets). At the end new socket run a feed back to the existing socket and connect that in the socket.

Existing

Cu----------1st socket - onwards to next existing socket

New

Cu----------1st socket broken, connect new feed to new sockets--- in / outs of new sockets, back to existing socket and re make ring.


You would end up with a connector block inside the existing socket, that is allowed.

You shouldn't use JB's that cabn't be accessed for mtce, so a jb inside a socket is acceptable.

As for UPS on and extension lead, why do you think that's a big fat "no" ?

It's unfortunate that most home offices have so many plug in / low watt devices that extension leads tend to be better that having 8 x double sockets for wall warts etc.

Last study I did had a 4mm radial to make sure the clients study appliances were on a separate circuit. Watch out for too many earth leaky items on the ring.

PC PSU's leak about 4-6 mA, and most rcd's trip at 30 mA. If that volume of kit is likely, then high integrity earthing would be prudent.

 

[ban-all-sheds]

I currently have a study, which has only 1 double socket in it. One socket feeds a RCD extension lead to which appliances are plugged into and the other feeds another RCD extension lead to which appliances are plugged into via a passthrough homeplug.

Unless those RCDs are unnecessary you don't have an RCD on that socket circuit, so you ought to sort that as all new sockets and any new concealed cables will need RCD protection to comply with the Wiring Regulations.

I've had this setup for many years but am unhappy with the use of extension leads full stop.

It's clearly worked for many years, so why are you unhappy?

I was planning to add a UPS purely for the 2 Servers to allow them to shutdown in a controlled manner if a power cut occurs.

Do domestic market UPSs have interfaces to signal loss of power? Not saying they don't - I've not looked.

However, as everyone knows the UPS would need to go direct into a mains socket, not an extension

I don't think everyone does know that - why do you think it's the case?

I would then be left with no alternative but to use an extension into the other mains socket followed by an extension lead off this extension lead and I'm not going to do that!

It's inelegant, but is that the only reason you are so against it?

Currently the existing socket is directly under the Consumer unit, so presumably is the first socket on the ring.

You must not presume.

Open it up and check - very often a socket directly under a CU is on a spur.

Assuming a feed from the consumer unit direct to the first socket (cable A) and a feed from the socket to the next socket in the ring (cable B) and knowing that the next existing socket in the ring is not in the same room which is the best way to connect into the ring?

This is a study, with a CU and a bunch of hardware in it, so clearly not a place where the highest standards of decor aesthetics apply.

The easiest thing to do (electrically and mechanically) would be to install dado trunking. Use a compartmented one so that you can run phone/data cables in it as well, and wire the sockets up using singles, that way you'll have loads of room to loop the ring along the trunking and back again to join the original cable.

I know you can drill around the outside and chisel out but is there an easier method? Can I hire a tool for the job?

You can, but you'll wish you hadn't.

Seriously - go with the trunking.

I am sure I can run the cables horizontally from socket to socket, can anyone confirm?

• 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.

 

[Paul_C]

Do domestic market UPSs have interfaces to signal loss of power? Not saying they don't - I've not looked.

Many do. Even some of the cheapest units now have a USB interface which can be used to monitor battery current, supply voltage etc. and to signal power loss to enable a controlled shut down.

However, as everyone knows the UPS would need to go direct into a mains socket, not an extension

I don't think everyone does know that - why do you think it's the case?

Seconded. Why?

 

[ban-all-sheds]

Cu----------1st socket broken, connect new feed to new sockets--- in / outs of new sockets, back to existing socket and re make ring.


You would end up with a connector block inside the existing socket, that is allowed.

The existing socket is directly under the CU. If it is the first one on the ring then no JBs are needed:

Remove cable from CU to existing socket.

Install new cable from CU to 1st new socket.

Continue through all new sockets and return to the existing one.

Carry out the usual continuity, EFLI, IR and polarity tests, record results on the schedule to the MEIWC - job's a good-un.

 

[ajrobb]

To wire a UPS, you could use a dedicated circuit in SWA (or steel conduit, etc) without an RCD. The outlet would need to be clearly labelled "UPS". This is fairly normal for freezers and boilers.

 

[SteveCav]

To answer questions raised: -

RCDs are on the extensions simply as they were the ones lying around - no other reason, the CU is obviously RCD protected.

Although I've been happy with the setup for a while, more and more hardware is going in and it looks a right mess and as I'm going to change furniture around etc I'd rather have it done properly

Yes, UPS do have an interface connection to shut down servers etc or network cards

I was told by APC (UPS supplier) to plug directly into the mains socket - they didn't explain why in detail and I can't understand it either!

Just assumed that the socket under the CU would be on a ring but will check - I'll be p***ed off if it is!

Personally I don't much care what the study looks like as it's a work area but my other half will and dado trunking will NOT be an option

I'd love to remove the cable from the CU but under Part P that's a no-no. Having had the CU replaced a couple of years ago and go the necessary piece of paper I don't want to void it!

Don't think I've missed anything!

 

[Paul_C]

I'd love to remove the cable from the CU but under Part P that's a no-no.

Adding sockets to an existing circuit is not notifiable work, unless in a kitchen or special location:

Exemption:

2. Work which -

(a) is not in a kitchen, or a special location;

(b) does not involve work on a special installation; and

(c) consists of -

(i) adding light fittings and switches to an existing circuit, or

(ii) adding socket outlets and fused spurs to an existing ring or radial circuit.

 

[ban-all-sheds]

RCDs are on the extensions simply as they were the ones lying around - no other reason, the CU is obviously RCD protected.

OK - that's good, but there's no "obviously" about it.

Although I've been happy with the setup for a while, more and more hardware is going in and it looks a right mess and as I'm going to change furniture around etc I'd rather have it done properly

Fair enough.

I was told by APC (UPS supplier) to plug directly into the mains socket - they didn't explain why in detail and I can't understand it either!

Oh well - best to do as they say. As you're putting in loads of sockets it's a non-issue.

Personally I don't much care what the study looks like as it's a work area but my other half will and dado trunking will NOT be an option

Then you are in for a load of work, it'll all take a lot longer, make a great deal of mess and then take more time to make good. How many sockets are you going to have? Where will they be? Will that many really look better than dado trunking?

Don't forget no more than 1/6th depth for horizontal chases.

I'd love to remove the cable from the CU but under Part P that's a no-no.

No it isn't.

But not doing all the testing I mentioned earlier is, so what about all that?

 

[SteveCav]

As I understand it adding in sockets to an existing ring only requires a minor works certificate, if that. If I add in a new circuit to the CU then it will definitely be notifiable - won't it?

I was planning on adding another 4 double sockets in the room. One next to the existing, 2 in the middle of the same wall and 2 at then other end of the wall.

The wall in question is an outside wall so breeze block, and air gap between that and plaster.

If I can get the missus to agree to dado trunking, would I take the feed from the CU and in that case Part P, which I'm trying to avoid and I'd have trunking down from the CU or have to make holes down the wall to feed the cable down.

As far as testing goes I'll do it myself

 

[ajrobb]

Ideally add sockets between two adjacent sockets in the RFC. Just ought to mention that another option is to add multiple sockets on a fused spur.

With the sockets all at the same height on the same wall as the existing socket, you'd have a horizontal 'safe' zone between the sockets where you can bury cables in the wall.

 

[SteveCav]

An option, assuming the socket under the CU is on the ring! Still need to check that, but it's a sod to get at. need to power everything down and move desk etc.

What is RFC?

 

[ajrobb]

What is RFC?

Ring Final Circuit (proper name for domestic ring main)

It is possible that the socket is on an unfused spur. In which case, you could replace it with a fused spur and add sockets to that.

 

[ban-all-sheds]

If I add in a new circuit to the CU then it will definitely be notifiable - won't it?

Who said anything about a new circuit?

I was planning on adding another 4 double sockets in the room. One next to the existing, 2 in the middle of the same wall and 2 at then other end of the wall.

That's an additional 5.

But, 4 or 5, that'll total 5 or 6 DSOs, which is 10 or 12 outlets.

I have 11 appliances to connect,

more and more hardware is going in

If I can get the missus to agree to dado trunking, would I take the feed from the CU and in that case Part P, which I'm trying to avoid

and I'd have trunking down from the CU or have to make holes down the wall to feed the cable down.

But you were talking about making chases the entire length of the wall..

As far as testing goes I'll do it myself

I'm not trying to be a smart ****, but the concept of you owning or having access to, and knowing how to use, a set of installation testers really doesn't dovetail with your misconceptions about regulations....

 

[SteveCav]

Yes, you are correct I can't count it will be 5 double sockets!

I have or have access to all the necessary testing equipment and know how to use them

As far as chasing out is concerned it would all be low down on the wall and behind desks i.e unseen. The room is painted not wallpapered and chases will show through the light coloured paint - been here before! Hence chasing vertically from the CU is not ideal for me.