Multiple 13A socket Stress!

[Vortex]

Hi,

I'm in the process of redecorating my study/office at home. The house was built in the 60's and the room has one single 13A socket.

I'm embarrassed to say that plugged into it I had the following (15) devices via a cascade of adapters giving total of 18 usable sockets.....

computer x 2, monitor x 1, notebook psu, reading light, speakers, adsl router, hub, answering machine, mobile charger, scanner, printer, dect phone, AA battery charger, radio. (and that does not include temporary devices like vacuum cleaners and son's guitar amp!!!!!!!).

Clearly this is not good practice and I intend to resolve matters by putting more double sockets within the ring main. I have proposed a "scorched earth" solution resulting in minimum 8 x new double sockets but SWMBO has aesthetic objections. I have 3 questions:

1. Is there a recommended upper limit to the number of sockets on a

2.5mm^2 ring main. (note there will not be a significant incremental loading issue...I'll just plug in all the same devices again!)

1. As an alternative an anybody recommend an elegant multiple (6 or so x

13A) surface mounting socket technology (not the crappy cheapo adapters you get hanging on hooks in B&Q)

1. Can anybody beat my 15 devices > 1 socket "personal best"

David

[Big Dave]

What is so wrong with that? The plug in the wall will have a 13A fuse, so no more than 13A will go down the wire, so no fire hazard - or am I wrong?

Fray Bentos

[Ian Stirling]

Ok, let's add it all up. Computers 140W Monitor 60W Notebook PSU 50W Light 20W Speakers 10W Router 5W Hub 5W Answering mac 5W Mobile charger 2W Scanner 5W Printer (inkjet)20W Dect phone 5W AA charger 5W Radio 10W

I make that about 350W. Not even approaching overload. Even add a cleaner and guitar amp going at the same time, and you'r still unlikely to top 2/3 load.

My "desk" runs on 1 13A plug. At the moment it's got (with hydra-like heads stretching into nearby cuboards). Oscilloscope, 0-150V PSU, 5V 40A power supply, 12-0-12 PSU, component analyser, computer, monitor, 20W fluorescant light, notebook charger,

3 phone chargers, scanner, signal generator, NiMh battery charger, 12V drill charger, sky digibox, VCR, DTTV box, computer case light, soldering iron, fan, printer, laser printer.

So, around 25.

I make the total load when all bar the laser printer is going around a 1Kw. (this would practically never happen, the PSUs are never all loaded at once.) Add the laser printer printing, and it can easily double that for short periods.

Even with everything on, plugging in a 1Kw heater probably won't cause the fuse to go.

However, in fact, all the sockets fan out from one 13A rated 4 way extension. Most of the subsidiary ones have 3A fuses, solely because getting to the main plug involves about 4 hours effort unloading and moving the desk.

I think it's poor practice only if you can't calculate the loads, and don't understand the consequences in the face of faults, or the cables are trailing, or prone to damage.

For example, my VCR shorting out could well take down my computer, until I replaced the fuse in the relevant extension.

But all the cabling is relatively neatly routed, out of the way.

[Dorothy Bradbury]

So you have... o A few FUSED trailing connector strips running off a single 13A skt o Regularly plug in / unplug a vacuum cleaner or such

Emphasised FUSED to show why it is safe.

You do not have... o A 2/3-way UNFUSED block-adapter in the single skt to trailing connector strips

Emphasised UNFUSED to show why it is not safe. o Connector strips are wrongly associated with UNFUSED block adapters o UNFUSED 2/3-way block adapter = 2/3x 10A to be drawn without blowing a fuse = fire

What I would note is this: o You plug/unplug/plug/unplug a vacuum cleaner regularly o This is not an ideal use of a connector strip (altho is safe in itself)

Thus you could: o Change the skt you have - to ease vacuum cleaner use

---- sink another single-skt alongside, grommet & double-earth to metal box

---- re-sink to a double-skt, more difficult re not damaging original cable o Verify the final plug feeding all the connector strips is sound

---- most probably a moulded unit with integral fuse

---- if DIY wired, consider an MK plug re better terminal-to-wire screw-down-camps

If you want multiple-IEC-plugs (PC) off a single 13A feed: o Farnell do 2-way for ~£2 -- free shipping for >£20 o RS do 3,4,5-way for unfortunately small to very silly amounts

[Bob Eager]

I wonder about the earth loop impednace at the end of the chain...

[Arthur]

I just discovered today that the 4 socked extension with tv, video freeview & telephone was connected live to neutral and neutral to live. And table lamp in other wall socket. Been like that for 3 years or so.

We've also been perseverring with no running hot water for some time and no heat source in the bathroom. When we plugged a 3kw kettle and 3kw fan heater together it would blow the fuse regularly.

"Oh well, I'm an idiot"

Arthur

[Farmer Giles]

Absolutely - it would certainly fail a PAT test.

[Ken]

Lidl or Aldi occasionally sell 12-way 13A extension boards - I liked the idea so bought half-a-dozen. They comprise 2 rows of 6 sockets, one above the other and with earth pins to the centre.

They are located:

- 1 in my wife's office, powering all her computer bits and office lamp;

- 1 in my office, powwering my computer, laptop, lamp, shredder, laminator and loadsa smaller bits

- 2 in my workshop (PSU's scope, soldering iron etc.

- 2 spare (mostly)

They are switched and generally fine, although sometimes plugs are difficult to push in and 'wall warts' can mean that only one socket of each stacked pair can be used, as the 'wart' box obstructs the other socket.

[Dave Liquorice]

Most of the devices mentioned are double insulated so earth loop from the appliance isn't an issue. Those that do require an earth, computers, monitors, printers are probably the higher load devices and so should be plugged in at the beginging of the chain rather than the end but load isn't really an issue either.

As a neat solution for the OP, change the single socket to a double and fit another double in a convient place for the vacume to be plugged in. Then use multi socket strips (6 way are fairly common) for everything else. CPC sell a small card to go in a PC that'll supply a fixed (but adjustable) voltage at around 1A, useful for speakers etc with the advantage that they go off with the PC and gets rid of one wall wart.

Something I spotted in a B&Q warehouse the other week was a strip that had load detection built in. You plugged the CPU into the first socket and when you turned it on the load was detected and all the other sockets came live, I think it was 6 way in total.

[Vortex3]

Good suggestion Ken,

There's a LIDL in town so I'll check it out.

Respondents so far seem to have the impression I have safety concerns. Actually it's the messy festoon of wiring that seems to have developed a life of it's own that really pees me off.

David

[Huge]

Olsen sell every imaginable combination of mains distribution strips. I have three 12 way ones in my study.

[Ken]

Again, Aldi had something similar - a six(?)-way with one output used to switch the others. Switching load was adjustable. Unfortunately, they have these things for only a few weeks each year so you'll have to keep calling in or watch their web site.

K

[Marcus Fox]

I have 10 or so appliances in one socket. 240 volts x 13 amps = 3120 watts. If the total combined power of all the appliances is less than 3120 watts, you should be OK. Note that vacuum cleaners and other heating devices like electric kettles and tumble driers can easily exceed 1500 watts, which uses up a lot of the allowance. The biggest thing on the circuit is probably my TV, at about 800W, followed by my computer and fishtank heater at about 150 watts and 100 watts respectively. When I vacuum, I plug that in outside my room.

Marcus

[Dorothy Bradbury]

Halving Plug & Cable Count: o 2-IEC-from-1-plug - Farnell 389-3170 - cheap £ 2.64

---- halves the # of cables/strip-sockets, 2-IEC start via a Y about 50cm from the end

Neatness: o Velcro Cable Ties

---- often used for optical cables, easy to undo & re-use continually, ~25p each o Spiral Wrap

---- large versions available, not just the small gauge stuff o 2.5m coiled 10A cable - 299-959 - at £11.15 ex VAT, Farnell

---- check the coiled length re pulling devices off the desk etc

RS 1-to-5-IEC is 1-IEC-to-5-IEC so would need the 1-plug changing, 367-0769, £40.99. The Farnell 1-to-2 could halve the # of cables at just £2.64 a go - price of an MK plug!

[copey]

why not fit dado trunking ? as it sounds like you use the room as an office very easy to install and would be future proof if / when you need more sockets?

& it helps :-)

[Capitol]

CPC sell a vertical 10 way extender, which has the advantage for small loads, that the lead does not need to be fully extended and is very neat, also because the sockets are arranged at an angle of 45deg. to the vertical, wallwarts can be inserted without fouling each other.

Regards Capitol

[Ian Stirling]

What sort of TV uses 800W? My 28" set uses about 70W.

[Owain]

"Vortex" wrote | I'm in the process of redecorating my study/office at home. | The house was built in the 60's and the room has one single | 13A socket. | I'm embarrassed to say that plugged into it I had the following | (15) devices via a cascade of adapters giving total of 18 usable | sockets..... | 1. Is there a recommended upper limit to the number of sockets | on a 2.5mm^2 ring main.

No. There is a limit on the floor area covered, and as the 32A ring circuit is a general-purpose circuit it should not be used where there is an anticipated greater load.

Also bear in mind that you can change the single socket for an FCU temporarily and run a fused spur from that until you have worked your way around the room/house to the other point in the ring, then break in to the ring and connect your new link, removing the FCU at that time.

| 2. As an alternative an anybody recommend an elegant multiple | (6 or so x 13A) surface mounting socket technology (not the crappy | cheapo adapters you get hanging on hooks in B&Q)

[Stefek Zaba]

I hear you, Dave! A few ideas which I've used:

- to avoid a silly "deep tree" of random 4way-to4way-to4way, I have a "2 levels only" rule I stick to - one good-quality 4- or 6-way strip as "master" distribution point, into which other 4- or 6-way strips go, and strictly end-loads-only into these. I've also wired up working areas at home for other family members using a "hardiwred distribution unit" (little box from RS, Maplin I think sell them too) which takes one mains feed in and feeds out 4 individually fused cables, using this to feed e.g. 3 multiway blocks and one heftier load such as a laserprinter

- where cost is less of an issue (e.g. at work!) I make much use of the DB2000 range of sockets: these have 13A (actually 16A) rated wiring for the "backbone", which you can daisy-chain quite responsibly, while each block provides some number (6/8/10/12) of 13A or IEC-320 sockets. IEC320 is the configuration very widely used as incoming chassis-fixed-plug and cable-mounted-socket on computer and similar kit - and takes up a lot less space than a 13A socket

- at the cost of slight inconvenience in having to unplug up to 4 items at once, you can use the "4 wires out" mains plugs sold at Aldi, ?B&Q, and so on. I would *not* trust these to supply a full 13A load, but to feed several small loads they're fine

- the greatest contribution to keeping the snaking wires under control has been cutting cables to get rid of excess lengths (and squirreling away the shorter 1m 13A-to-IEC320 cables HP ships with some of its laptop power adapters ;-). Especially where I work, there is a huge quantity of accumulated 2m-long 13A-to-IEC320 cables, so cutting them down to length, and replacing the moulded-on 13A plug with a rewireable one, with an IEC320 plug to go into an IEC320 socket (or one of those "hifi connection units" also based on the IEC320 pattern), or wiring into one of they there 4-cables-to-one-13A-plug things, is an entirely responsible use of company assets ;-)

- the second-greatest contribution, practised most fully in my wife's office (she has an aversion to snaking cables) is to use various cable-management Thingies (cable ties, velcro ties, "open" trunking) fixed to the underside of the desk to keep them not only off the floor but out of sight

- and the greatest disservice to cable management is direct-plug-in wallwarts - these are often physically too big to go next to each other, or even next to an ordinary 13A plug, in a multiway mains block. A couple of times I've even had to wire up an IEC320-plug to trailing-13A-socket to use these damned things

- doing "careful" wiring on the mains side allows a single "master" switch - e.g. in the den where our teens have a boatload of computer, music-making, and ee-lek-tron-ick ent-uh-tain-munt kit, there's a single Big Red Switch which supplies power to one 8-way block which feeds further blocks; being able to turn the whole lot off at bedtime at one place is a definite Win, and having said Big Red Switch in a prominent, convenient position (and making sure they're in the habit of using it, 'cos Dad turns it off each night!) increases the chance that when matey comes round with the highly dodgy guitar amp with the "ground lift" (earth wire disconnected) they'll have a better chance of cutting the power than if they have to start working out what's plugged in where. Putting a handy 8-way strip on the leg of the support for the keyboard is another way of making it easy for them and mates to do the Right Thing...

HTH - Stefek

[Ian Stirling]

What is the maximum earth loop impedence?