Number of double sockets on a 32A ring

[AMEdinburgh]

Is there a suggested maximum number of sockets for a 32A ring? It is for a new office room with two PCs three screens, three printers and all the small power stuff that goes along with IT. I am considering a benchtop profile installation and a low down dado rail cable and power profile arrangement with lots of sockets rather than having trailing extension leads.

All helpful comments gratefully received

 

[plugwash]

no there is not a recommended maximum number of sockets because quite frankly number of sockets is a very poor indicator of likely load. Floor area is better and the guidelines in the IEE regs are based on this.

If you are putting more than a couple of PCs on a circuit you should really be installing to high integrity earthing

 

[oharaf]

There is no 'limit' to the number of sockets on a 32A ring final as such, thou there is a restriction through floor space, I think this is 75msq (would need to check this)

However consideration needs to be given to what exactly it is you are likely to be running on this circuit.

By the sounds of your post you are installing a small office, couple of pc's, screens and printers.

This is unlikely to exceed the circuits load capacity.

If you can provide exact details of the space size, and the power rating of each appliance a quick calc can be done to verify this

oh yes and the high integrity earth as mentioned by plug

 

[AMEdinburgh]

The room in question is only 2.4m x 3m as a single person office.

I can't see the total load exceeding 3KW even if the printers are all printing as most of plug in transformers are only a few watts for accessories.

What is meant by high integrity earth?

 

[ColJack]

the earth wires of the circuit must be connected to seperate terminals on the back of the socket and seperate terminals at the consumer unit. this ensures that there is always a path back to earth should an earth cable come loose..

if it's a radial then an earth wire needs to be taken back to the consumer unit from the last socket

 

[ban-all-sheds]

1) It's not needed unless you expect the total cpc current to exceed 10mA.

2) If it is needed, then just connecting the existing ring cpc to separate terminals on the back of the sockets won't do - you need to add a second separate cpc ring...

 

[RF Lighting]

2) If it is needed, then just connecting the existing ring cpc to separate terminals on the back of the sockets won't do - you need to add a second separate cpc ring...

No you don't.

To avoid hi-jacking this thread, I will start a new post to end this argument once and for all.

 

[ban-all-sheds]

To avoid hi-jacking this thread, I will start a new post to end this argument once and for all.

Which will probably go round and round and round, fuelled entirely by the refusal of people to take notice of the simple word "individual"...

 

[Spark123]

Maybe the regs could have been written clearer, the guidance notes pretty clearly show what the spirit of the regulations is on the subject.

 

[AMEdinburgh]

Thank you to everyone and in particular RF Lighting and the photo of the diagram. Diagrams are always helpful to the novice

Should the earth connectors always be terminated separately in any socket as I've not often seen that very often and had work inspected and passed with them joined together in a single connector on the back of a socket.

I've used the second one to connect an earth to the metal box where fitted so the screws in the socket place are grounded. Is it better practice to split the ring earths and add the box earth to one connector with one from the ring.

Is there a convention regarding the second earth at the consumer unit. I've generally, out of not knowing otherwise, connected the earth to the numbered earth for the circuit breaker being used. Does the second earth simply go anywhere where there is a free connector and is it good practice to label it with the breaker number or a description of the circuit?

 

[ColJack]

high integrity earthing is not normally needed in domestic situations unless ( as already mentioned above ) you forsee the use of several items of equipment with high earth leakage ( such as computers and monitors which have EM shielded parts adn cables that leak induced current to earth )

the convention with the earths at the distribution board is to put the 2 ends under different screws..
generally if you had 2 rings in breakers 1 and 2, then you'd put one cpc end from ring 1 and one cpc end from ring 2 under the screw marked 1, and the remaining cpc ends from rings 1 and 2 under the screw marked 2 ( since in general you have an equal number of earth screws in the bar, to the number of breaker ways, with maybe a few spares and the ones reserved for bonding )