Double Feed into Switch

[securespark]

So the socket is no good at 253V?

 

[RandomGrinch]

'13A per socket outlet (except 3 gang which is 13 amp in total)"
Certainly 'implies' 26A!

PDF attached.

EDIT:
A more modern brochure has subtley changed the wording:

 

[JohnW2]

So the socket is no good at 253V?

Kind Regards, John

 

[JohnW2]

... '13A per socket outlet (except 3 gang which is 13 amp in total)". Certainly 'implies' 26A!

Yes, it certainly would seem to imply that. However, see my post #11 above - it seems that even the MK Technical folk were not totally sure what "..per socket outlet" means, since that was apparently written by the Marketing Dept., not them!

However, as I've subsequently written, a subsequent search of of shelves found several different makes of double sockets, all of which had just "13A" embossed on their backs. I don't think that (m)any of us believe that a double socket is only 'rated' for 6.5A + 6.5A, or for 13A + 0 (which would make its existence as a 'double' socket a nonsense), or anywhere between those two extremes, so the only real interpretation of that "!3A" marking is that it means 2 x 13A for a double socket.

Kind Regards, John

 

[big-all]

Neither a washing machine nor a dishwasher draw high currents for appreciable periods of time. I think it's when one of the appliances is a dryer (which can draw high current more-or-less continuously) that some people experience (socket) over-heating problems.

indeed once a washing machine is past the heating cycle it is sub 4amps and suspect a dish washer will be similar it seems like 2000w or less now seem to be what driers and washing machines are so a 13amp double [rated 20 amp] would be unlikely to give problems or concern

 

[JohnW2]

indeed once a washing machine is past the heating cycle it is sub 4amps and suspect a dish washer will be similar it seems like 2000w or less now seem to be what driers and washing machines are so a 13amp double [rated 20 amp] would be unlikely to give problems or concern

Quite so.

The below (from 'Wiring Matters' Spring 2002), which we have looked at before, gives a rough idea of the electricity demands within a kitchen, and shows that even if Washing Machine, Dishwasher and Tumble dryer are switched on simultaneously (and kettle and toaster also briefly), after the first 30- minutes the total current draw is never appreciably above 20A..

Kind Regards, John

 

[big-all]

o

Quite so.

The below (from 'Wiring Matters' Spring 2002), which we have looked at before, gives a rough idea of the electricity demands within a kitchen, and shows that even if Washing Machine, Dishwasher and Tumble dryer are switched on simultaneously (and kettle and toaster also briefly), after the first 30- minutes the total current draw is never appreciably above 20A..

View attachment 256661

Kind Regards, John

ok maybe i am wrong ??
you graph shows a warm rinse ??
does this happen ??
thought it was cold after the initial heat but off course i am -----still learning

also it shows a constant 2kw plus that simply doesnt happen for 2 hours as the the heating cuts in and out more so as the washing dries indeed drying a load in my tumble cost about 1.8 units over a 2hr cycle as it cut in and out rather than the infered 5kw in your chart
not a criticism in any way you understand, as i suspect 10 years ago assumption where relied on far more than actual accuracy

 

[RandomGrinch]

Having just read through BS1363-2:1995 ( ),
I have come to the conclusion that a double socket, is in fact, a single flush socket outlet, with two sets of socket contacts:

And as 'ALL' socket-outlets should be marked with the rated current,

Then a socket-outlet with two sets of socket contacts marked with a single 13A symbol can only be rated at a total load of 13A from both sockets!

So the socket is no good at 253V?

 

[JohnW2]

Having just read through BS1363-2 ( ), I have come to the conclusion that a double socket is in fact a single flush socket outlet, with two sets of socket contacts:

Yes, I can't criticise you from drawing that conclusion from what you have quoted, and ....

... And as 'ALL' socket-outlets should be marked with the rated current, .... Then a socket-outlet with two sets of socket contacts marked with a single 13A symbol can only be rated at a total load of 13A from both sockets! ...

... and, again, I cannot argue with your logic of the conclusion you have drawn, BUT I don't think that any of us believe that such is what the "13A" marking on the back of double sockets is meant to mean...

... for a start, it would make no sense for a manufacturer to 'rate' (and therefore 'mark') a double socket as having a current-carrying-limit of 13A total, when the Standard required that the product had, at a minimum, passed a test at 20A total.

Furthermore, returning to the MK Data Sheet you quoted, it would make no sense for them to have written "13A per socket outlet (except 3 gang which is 13A in total)" if the "13A per socket outlet" also meant "13A in total" for 2-gang sockets

Kind Regards, John

 

[RandomGrinch]

... for a start, it would make no sense for a manufacturer to 'rate' (and therefore 'mark') a double socket as having a current-carrying-limit of 13A total, when the Standard required that the product had, at a minimum, passed a test at 20A total.

Interesting quote from a certain other forum here

 

[JohnW2]

ok maybe i am wrong ??

I'm not sure what you think you might be wrong about. I certainly agree with your conclusion (agreement with me!) that a WM+Dryer would not usually result in >20A total for appreciable periods of time (more than, say,309 mins).

you graph shows a warm rinse ?? ... does this happen ?? ... thought it was cold after the initial heat but off course i am -----still learning

Are you talking about the 'Hot Rinse' of a dishwasher. If so, then, yes, it definitely happens, and it is primarily by getting the contents very hot that they are dried. Have you never opened a dishwasher just after a cycle has finished? If you have, you will have been confronted by great clouds of steam (which instantly fog up my glasses if I'm wearing them at the time )!

... also it shows a constant 2kw plus that simply doesnt happen for 2 hours as the the heating cuts in and out more so as the washing dries indeed drying a load in my tumble cost about 1.8 units over a 2hr cycle as it cut in and out rather than the infered 5kw in your chart ...

I'm sure they vary, but my tumble dryer seems to run at roughly full heating pelt almost continuously.

The below shows what happened iin my house here on a recent night (early hours of morning) when we had our DW on followed, separately, by the dryer (with something else, I can't remember what, coming on between them!). The graph is of my entire ground floor electricity usage with, as you can see a roughly constant ~600W background usage (lights, fridge, maybe TV, CH etc.) to which the usage of the two appliances is added. Blue line is daytime electricity and red is 'cheap' E7 electricity, from 00:30 onwards.

The "Heat/Wash" and "Hot Rinse" parts of the dishwasher cycle are clearly shown, as is the fairly constant, continuous current draw by the dryer throughout the ~80 minutes it was on (it appears to gradually diminish slightly during the period but, as can be seen from after it finished, the 'background' usage had been diminishing - presumably due to minor things, like TVs etc., some lights and maybe CH being switched off). The graphs are derived from usage data recorded roughly every 12 seconds.

Edit: I should have added that my dryer appears to only draw about 1.5kW, not 2kW.

Kind Regards, John

 

[JohnW2]

Interesting quote from a certain other forum here

That's the quote from the IET forum, around 12 years ago, which I presented in post #11 above.

As it says, it apparently came from some MK catalogue, but no-one has been able to find the source, and the MK tchies I talked to about this had a few years back claimed to have no knowledge of it, or what it said!

I really don't think there is much doubt that most, possibly all, manufacturers believe that their double sockets are 'rated' for 2 x 13A, and many may well have satisfied themselves (by testing) that such is reasonable. As I recently wrote to bernard in this thread, although the Standard only requires, as a minimum, that the product passes a temp rise test with 14A+6A, that does not prevent a manufacturer testing at higher currents (e.g. 13A+13A, or perhaps 14A+12A!) and then speccing /'rating' their product accordingly.


Kind Regards, John

 

[RandomGrinch]

That's the quote from the IET forum, around 12 years ago, which I presented in post #11 above.

As it says, it apparently came from some MK catalogue, but no-one has been able to find the source, and the MK tchies I talked to about this had a few years back claimed to have no knowledge of it, or what it said!

Kind Regards, John

Aaah, sorry.
I read the post at the time, but didn't expand the quote.

...and it sounds more like an email, than a quote from a catalogue...

EDIT:
That exact quote also seems to be all over the internet, on many different forums - being the only statement available about double socket loading.... and without naming an actual source

 

[JohnW2]

Aaah, sorry. I read the post at the time, but didn't expand the quote.

No problem - we've all been similarly guilty in the past!¬

You may well have missed the final paragraph of my last message, which I added as an edit.

Kind Regards, John

 

[securespark]

I don't think that any of us believe that such is what the "13A" marking on the back of double sockets is meant to mean...

When Logic Plus came on to the market, I read MK's stuff about the rating of sockets.

I spoke to a bloke in MK's Tech Dept back then and he said that he believed that every socket was rated at 13A and the 19.5A test was just them being able to prove that the product could withstand supplying a 13A load continuously, with a percentage added on to show that the socket does not disintegrate at 13.5A. He said the 19.5A figure represented a load that exceeded 13A by 50%.