sockets on ring main

[Sam]

Hi,

My house has one socket per room and it's often single sockets rather than double ones! Upgrading single to double should be straightforward but I wondered about fitting an extra double socket on the other side of each room. Is there a limit on how many sockets you can have on a ring as this will be doubling what I presently have?

I had a search but can only find limits on cable length, earthing, etc. As long as these are ok can I add sockets as necessary?

Should I use 25mm or 35mm boxes?

I know the on site guide is recommended here but it quotes the 16th edition regs and I understand we are now on 17. When will a revised guide be published?

TIA, Sam.

[David Hansen]

On Thu, 14 Aug 2008 10:23:08 GMT someone who may be Sam wrote this:-

No limit on the number of sockets, provided a few conditions are met.

is a good source of information.

[Dave Plowman (News)]

In practice in most houses, no. It's mainly a question of floor area.

Yes - but remember rings aren't designed for lots of high continuous loads like heating etc. So one ring in a house with a fan heater in every room wouldn't be a good idea. But for all the 'normal' things we need lots of outlets for like the various types of electronic equipment they're fine.

Personally I always use 35mm - 25mm are generally no easier to install and can make the wiring rather tight.

Don't think there are any changes as regards this point.

[jgharston]

A single ring mustn't serve a floor area of more than 100m^2 which is more than a standard domestic installation, so you can ignore that.

If you've got floors up and doing wiring, then I'd advise to put more sockets than you think you need - a socket with nothing plugged into it does no harm - particularly in TV alcoves. Think TV, video, cable/satellite, DVD, game machine and that's already three double sockets before trying to plug in a lamp, telephone charger, answer machine, etc.

If you're completely rewiring, I'd also advise a seperate ring for the kitchen, particulalry if you have washing appliances in the kitchen, eg toaster, kettle, microwave, cooker ignition, radio, washing machine, fridge, freezer, dishwasher.

-- JGH

[jgharston]

Oh yes, you can't have more than one outlet as a spur, so as long as it's just a ring, no problem.

[John Rumm]

Note that the "one outlet" does include one double socket per unfused spur. (you can have as many as you like on a fused spur, but the total load is limited to 13A then)

[ARWadworth]

And 35mm is often required should flat plate chrome sockets ever get fitted at a later date.

Adam

[Dave Plowman (News)]

Yes - although IIRC some will fit 25mm boxes.

Same applies to lighting switches - plaster depth boxes *may* save a small amount of time when rewiring but you'll regret it later when you decide to fit a dimmer, etc.

[nightjar]

Indeed. Except where doors prevented it, I put two double sockets in every corner of every bedroom and four double sockets in every corner of every reception / living / dining room and I still don't have enough in some places.

Colin Bignell

[dennis]

Yes, screwfix do some fused 4 way convertors to make a single or double into four outlets. You can put one of those on a spur.

[John Rumm]

You might even argue that you could use two (since they will be fused at

13A per four, or 26A total, and a double socket without fuse would also be overload protected at 2 x 13A)

[dennis]

You could argue that you can fit more if you put 3A fuses in them.

[John Rumm]

Not much practical advantage though. If you really want loads of sockets for low load appliances, then using ordinary doubles after a FCU would work out cheaper.

[Dave Plowman (News)]

I doubt it - subsequent owners would immediately replace them with 13 amp ones. Think that's why all new IEC leads etc have cable capable of blowing a 13 amp fuse in event of a short.

[Sam]

If you have four doubles in each corner are they still all on one ring? I'm thinking of the earlier post that said a socket with nothing in it takes no load but eight sockets in every room will add up to a hefty current if they are all used at once. Thanks.

[Sam]

Do you use 35mm for light switches too? Thanks.

[Sam]

Thanks. It seems the 17th ed is the on site guide, it's just it's not called that! £13.60 ex vat sounds quite reasonable too.

[John Rumm]

No, you are looking at a book by John Whitfield which is intended to be a readable guide to the regs, not the regs themselves (which are quite heavy going, and don't contain much in the way of background information supporting why they say what they do).

These are the regs:

on site guide will look like this when published:

[John Rumm]

Not usually - 16 or 25mm

[Dave Plowman (News)]

The load depends on what is plugged in. Pretty well everything gives the current consumption somewhere on it - in watts. A ring can handle approx

8000 watts which is 130 60 watt table lamps. So as you can see unless you're using it for heating you're unlikely to overload it.