Traditionally house builders rarely seem to install enough mains sockets to satisfy the gadgetry needs of your average family. My granny had very few mains-driven mod-cons and could cope quite happily with only one or two sockets per room, even going so far as to diligently switch them all off at night, however for most of us a couple of outlets just isn’t going to cut the mustard, or indeed power the TV, PlayStation, DVD, DigiBox, mobile charger, floor lamp and laptop. At least, not simultaneously... unless you start hanging multi-way adaptors off your wall sockets.

I get asked about whether these things are safe or not and the short answer is yes, but only if used properly. So let’s have a closer look at what’s out there and where things can go wrong...


extensions
Good and bad examples; the unfused cube at the top and the long, thin six-way strip under it being the latter. The cube isn't fused, and the strip permits insertion of an earth pin of a plug rotated 180 degrees which would open the shutters on the line/neutral receptacles thus defeating the safety mechanism.


Two, three, four, six, or eight way adaptors?
Domestically these things come in a range of sizes from simply doubling a socket outlet to octuplet-ing(!) it. The important thing is that any modern multi-way adaptor should be fused to a maximum of 13A, a legal requirement which may not be present in old, counterfeit or foreign adaptors not correctly built to BS1363 Part 3. In (simplified) theory, a fused adaptor could have any number of sockets so long as that 13A current isn’t exceeded. In reality, an eight way adaptor is likely to be the biggest you’ll find on the high street, but even if you only have a two-way cube (as pictured below), check it has its own fuse. If not, don’t use it and invest a few pennies in a modern replacement.

 

cubesTwo cube adaptors, the one on the left has no internal fuse unlike the adaptor on the right.

 

There’s a fuse in the plug of each appliance so why would I need one in a multiway adaptor?
The wall socket you’re using is usually on a ring main (domestically), however the socket may be a spur off the ring, especially if it was added after the house was built. Often, most people just wouldn’t know, or indeed care if a socket is ring, radial or spur fed. The problem comes if an unfused spur has been fitted using 2.5mm2 cable which is quite common, however the wiring regulations state that only one single or one twin socket may be connected to that spur cable (regulation 433.1.103). The reason for that is because 2.5mm2 cable can quite happily carry the sub 13A current a single device may draw, however if you connect two or more devices to that socket using an unfused multiway adaptor you may well exceed 13A. If you exceed the current carrying capacity of the cable, which can be as low as about 18A depending on how it’s been installed, then that spur cable may overheat and it will be a long time before the 32A breaker or 30A fuse protecting the circuit as a whole kicks in. Having a 13A fuse in the multiway adaptor will ensure the load should never exceed the capabilities of the host socket. Such a fuse will also protect the adaptor itself if other adaptors are daisy chained off it.


Can multiway adaptors be daisy chained?
If the first adaptor in the chain is fused then running one board off another should mean you don’t exceed the rating of the host socket or the first adaptor in the chain, however having additional plug and socket connections and increased cable lengths in-line will increase the overall resistance of the wiring which can lead to other problems such as voltage drop, localised heating, impaired earthing, increased breaker reaction times, trip hazards and other such issues which would have your average Health and Safety officer waking up in a cold sweat in the middle of the night. In short,daisy-chaining and long lead extensions should be avoided.


Know your loads.
High current loads such as appliances with heating elements and motors, or noisy earth loads such as some items of computing equipment are best kept as close to the host socket as possible. Low current loads, especially Class II items which don’t require an earth such as mobile phone chargers are better suited to occupy the sockets towards the far end of the adaptor. This is especially true if you’re being naughty and daisy chaining adaptors or using long line extension leads despite my advice in the previous paragraph. 


Coiled extension leads.
I’ve already mentioned some problems with long leads, however I should also point out the danger of not fully uncoiling a long extension reel. When it comes to the kind of reels you can wind up, they should really only be available in the following sizes...

Up to 12m for cables with a 1.25mm2 core
Up to 15m for cables with a 1.5mm2 core
Up to 25m for cables with a 2.5mm2 core

That said, it doesn’t take much searching of DIY store websites to find 30m, 40m or even 45m reels on sale. Technically such beasts should fail a PAT inspection on length alone according to the IEE Code of Practice for In Service Inspection and Testing of Electrical Equipment (my kind of bedroom reading), especially if they don't have an integral RCD. The IEE Code of Practice says "..the equipment supplied [by a long extension reel] may not function correctly due to voltage drop in the cable. There may also be a risk of fire due to overloading, and under fault conditions automatic disconnection may not occur within the prescribed time."

45m45 metres??! And it doesn't even have a built-in RCD!


When it comes to extension reels, buy a sensible length. Unless you want to plug something in at the far end of a very long garden, you probably don’t need to invest in multi-metre monsters. Whatever the length, you should fully unwind the cable and check along its length for any damage before use. Obviously such winding/unwinding and checking becomes more labour intensive on longer lengths, so shorter reels make life easier.

Failing to fully unwind the reel can cause it to overheat under high load conditions resulting in it ending up resembling a smoking doughnut. Some have a thermal cut-out built-in, but relying on a safety device to operate is akin to being a cure rather than prevention and is best avoided.

One other note when using extensions, especially around power tools and gardening equipment, is to ensure the socket you are plugged into is RCD protected. If you’re not sure, select an extension reel with inbuilt RCD protection or invest in an RCD you can connect in-line. You’ll be glad you have one if you ever end up running the lawnmower over the cable!


Check for British Standards.

British Standards are world leaders so look for the kitemark and BS1363-3 marking and buy known makes from reputable retailers. Beware of counterfeit products from dodgy market stalls or auction websites as they may claim to be compliant with British Standards while being anything but. FatallyFlawed have information on what to look out for here.


Adaptors for foreign equipment.
One last point to make you aware of is to look out for non-compliant converter adaptors for foreign plugs. Two such identical adaptors are pictured below and neither are BS1363-3 compliant. The problem with these adaptors is that they do not have shuttered sockets, the receptacles are oversized and the casing is too close to the pins risking a finger coming into contact when inserting or withdrawing it from a socket. You can see the live metalwork exposed in the adaptor on the right and it's just waiting for a child to insert a finger or metallic object into! These adaptors are also unfused which is another BS1363-3 no no. Foreign appliances may be designed for 110v or, if faulty, rely on lower current protection favoured by the radial circuits in other countries, so hooking them in to a 230v UK ring on a relatively high 32A breaker is going to make for a loud bang and/or a nasty smell at best. No fuse means the appliance will burn which won't be healthy for anyone holding on to it at the time. Incidentally, the adaptor on the left, removed from an office, is interesting in that a PAT test firm has given it a pass sticker. Had the PAT inspection been performed properly, this adaptor would have failed the test because of its inherent non compliance with BS1363-3.

foreign

 

Finally, to recap, there is nothing wrong with using a multiway adaptor so long as it’s fused, manufactured by a reputable manufacturer, carries British Standard markings, has a sensible lead length, has no obvious signs of damage/overheating and is relatively modern.

That said, if you need extra power for the long term in a room that’s short on sockets, it’s better to invest in having extra wall sockets professionally installed than snaking multiway adaptors and extensions around the room. Installing extra sockets doesn’t have to break the bank and can often be easily achieved without too much disruption. Contact me for a chat about your particular circumstances and I’ll have you sorted out in no time!