Absolute amateur wants to know if I'm overloading

ninebob · 10 Apr 2004

Hey,
I came across this site by chance, but it seemed like the perfect opportunity to ask about something that's been worrying me.
I moved into my flat 7 months ago, and the lack of sockets means that I currently have the following set-up:
The living room has just one double socket:
side one goes to a double block adapter (fused 13amp), running to a fan heater (max 2400w) and an uplighter (60w).
side two (here's the possibly worrying bit) runs to a 4 way trailing socket, into which i have plugged in 1. the computer and the moniter (on a 2-way block adapter) 2. the speakers (transformer) 3. the printer (transformer) 4. Another trailing socket (this time a 6 gang), running to 1. cordless phone (transformer) 2. TV, 3. VCR no.1, 4. VCR no.2, 5. Cable box, 6. Another uplighter (60w).
Several friends have told me this is ludicrous, but as far as I can see, if I don't load either side of the double socket above 13 amps I'll be fine, no matter how many trailing sockets and/or adaptors I use. I'm intelligent enough to realise that the side I have the fan heater and the 60w uplighter is fine - but I'd be interested to learn the total power draw from - PC, Monitor, Printer, Speakers, TV, Cable TV Box, 2 x Videos, Cordless Phone, and a 60w Uplighter. I reckon they're all pretty low wattage so the total should be less than 13 amps and therefore OK.
Your comments appreciated,
Si x

dingbat · 10 Apr 2004

In essence you are correct in that if you overload either original plugtop fuse it will blow - that's what it's designed to do. But as a general principle the more mechanical connections you have on a circuit the more prone you are to poor contacts, arcing and subsequent fire risk. And the more trailing leads you have the greater the chance of snagging/trapping/tripping etc...

As for working out your loading, every appliance should have (somewhere) a label which gives you this. Why not work it out yourself. And then get the place rewired anyway - with that few outlets it's indicative of quite an old installation.

ninebob · 10 Apr 2004

Thanks Dingbat,
I don't think the install is that old, it's a fairly recent conversion of a large terraced house into flats, with a modern consumer unit - I just don't think they bargained for the amount of appliances someone might want in their lounge! The physical location of my trailing sockets isn't a problem either - everything's neat and tidy, I was just concerned about having so many trailing sockets and block adapters running off one double socket. If someone can reassure me that it's safe, as long as I dont go over 13 amps total (by my maths thats about 3kw, right?) I'll be happy - I would just appriciate someone's estimate for the total of the appliances previously mentioned...
cheers,
si x

dingbat · 10 Apr 2004

The current IEE recommendation for sockets in a living room is 6 to 10 twin socket-outlets with two located close to the TV aerial. Having a modern CU does not necessarily mean the cabling has been upgraded, but in a conversion it should have been. (A lot of householders regard the, now very old, Wylex push-button MCBs, or Square D, clip-on MCB units as modern. I see a lot of these posing as rewires.)

If you have a spare weekend (hey, look, it's Easter!) it would really benefit you to get under those floorboards and increase your socket provision. Why? Peace of mind. A chance to put your sockets exactly where you want them. Increase the saleability of your flat in the future. No need then to count up the loads... (I'm not even going to attempt that! 13A x 230V = 2990W, by the way)

Have fun!

securespark · 10 Apr 2004

A 13A socket single or double has a maximum load of 13A. NOT 13A per side as suggested.

I would discard the block adaptor straight away - they don't take kindly to being loaded up with high-current appliances. The other side is not greatly loaded, and I estimate your total load on both sides to be under 13A, but as has been mentioned, it is not good practice to have multiple connections, trailing leads etc...and they should never be run under floorcoverings.

plugwash · 10 Apr 2004

securespark where did you find that you are not supposed to load a double socket to more than 13A total

is it a wiring reg?
does it come from manufacutrers data?

looking at this

Current rating:
13A per socket outlet
(except 3 gang which is 13 amp in total)

Big_Spark · 11 Apr 2004

Plugwash. BS1363 - pt2 deals with this issue, and it states quite clearly that sockets made to this standard will only be rated at 13A maximum loading.

Now I grant you that in theory this means that a double outlet has a potential 26A load bearing capability, but this is not the case, which is why BS7671 only refers to double sockets as single points not double points.

Unfortunately is is one of those areas that those who have the power to inform the public of the real situation fail to do so.

Here is a quote from the MK page you linked to

All Logic Plus 13A socket outlets comply with
BS 1363: Part 2: 1995.

plugwash · 11 Apr 2004

i would think that is the difference between parts that just about meet the standard and stuff like mk which is built to a much higher quality

ie mk build thier sockets to take full load on both sides even though the standard does not require it

Big_Spark · 11 Apr 2004

plugwash said:
ie mk build thier sockets to take full load on both sides even though the standard does not require it

If you pull 26A out of any socket faceplate you will cause it damage over a pretty short space of time, regardless of manufacturer.

I agree MK are head and shoulders above everyone else, but even their kit is not superkit (if you know what I mean

)

MK will not sanction their accessories used in this way.

plugwash · 11 Apr 2004

13A plugs and sockets are pretty tough

running a 9KW shower through one is not unheared of and i don't think it did any seiorus damage

more seriously if the rating was per complete outlet plate then why would they put a seperate comment about the 3 gang being 13A total

Big_Spark · 11 Apr 2004

plugwash said:
13A plugs and sockets are pretty tough

running a 9KW shower through one is not unheared of and i don't think it did any seiorus damage

more seriously if the rating was per complete outlet plate then why would they put a seperate comment about the 3 gang being 13A total

Firstly, it is that attitude that gets people killed. I am not insinuating you advocate this type of behaviour, just stating that because you believe something, doesn't make it so.

Regarding the 13A fuseholder, it was the only way the BSi would give them a rating.

Yes it is daft, confusing and a load of old tosh, but that is what it is. I agree that as you can happily plug two appliances into one double socket, each with a rating of 12.8A, but the BSi only rate the socket at 13 total, knowling how they will be used, is pathetic and narrow minded and needs changing.

Regardless of what you or I think Plug, the standard is the standard I'm afraid.

As for running a 9Kw shower via a plug...I'd love to see how as the fuse would be in orbit long before you got to 9kW

ban-all-sheds · 11 Apr 2004

Jim - I agree about what the BS standard says, but parts of them are often minima, and plugwash does have a valid point - why on earth would MK explicity make the distinction about the 3-gang socket being 13A in total if "13A per socket outlet" doesn't mean that their double sockets, fully in compliance with BS 1363: Part 2: 1995, are rated at 26A?

I don't imagine that BS 1363: Part 2: 1995 says that socket outlets must not be designed in such a way that more than 13A can safely be drawn from them.

As for the shower on a plug - anybody mad enough to attempt that would not balk at replacing the fuse with a bit of coathanger or nail.

securespark · 11 Apr 2004

I had a chat to Tenby Technical a few years ago, as one of my customers ws using a double to feed a washer and seperate dryer used simultaneously. They said they had tested their 13A d.s.s to a total of 16A continuously for 7 days and there was no breakdown, but higher than that and there were signs of distress.

Im not advocating overloading a socket........

ZenStalinist · 11 Apr 2004

Yes... Have you also noticed how you can buy those cluster adaptors to adapt one socket to fit two plugs unfused? I have one such adaptor. I don't think it's incredibly safe for the average John Clutz. It says on it 'MAX LOAD: 13AMPS', but does John Clutz know exactly what that means, and how to check he's not overloading it? Does he even care? Probably not. All I can say is I'm thankful that triple sockets are fitted with a thirteen amp fuse.

Big_Spark · 11 Apr 2004

OK, I have been hunting for clarification on this as I do consider it extremely imnportant as a matter of safety.

Here is a quote from the Technical Section of the latest MK catalogue which arrived in the post Yesterday.

All MK socket-outlets are manufactured to comply with BS1363 part 2: 1995 and are rated at 13A per unit. Double socket-outlets have been manufactured and tested to exceed this rating by margin that allows electrical safety and reduces the risk of heat and mechanical damage to components due to overloading. It should be noted that BS1363 part 2: 1995 does not allow double sockets to operate at twice the permissable maximum loading and it should be remembered that double socket-outlets are not manufactured to be able to withstand a 26A load for sustained periods of time.

Research by ourselves and third party organisations has shown that all MK double sockets can safely withstand a continuous load of 19.5A for an indefinite period. Increasing the load slightly will begin to cause heat and mechanical stresses on the components in a relatively short period. Testing showed that a load of 22.3A was sufficient to cause heat stress that would cause a browning of the faceplates and sufficient heat to cause insulation damage to cable cores. A load of 24A for 43 hours was sufficient to cause significant heat damage to the material in which the socket-oulet was situated and within 75 hours sufficient to cause significant damage that would lead to the very real potential of fire.

MK recommend that users of their sockets consult professional design Engineers when designing installations to avoid the possibility of heat and mechanical stress to components and installations caused by overloading of MK socket-outlets.

I think MK's words speak better on this subject than anything I can say.

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Absolute amateur wants to know if I'm overloading

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