Socket Location for Oven and Hob

[EFLImpudence]

Yes, I know you are saying what some other people believe.

However, what I am saying is that -

if people believe a double socket must not be loaded with two 13A loads because the socket is only rated for 20A then to prevent two 13A loads being connected by Mr.Public it must follow that the socket should be protected by a 20A OPD.

I do not recollect this having been mentioned by anyone nor stated anywhere before, therefore double sockets must be manufactured to work with 26A of load (as would the 20A switch). Why double sockets are said to be tested only to 20A, I have no idea.

That some double sockets (and plugs) overheat is presumably just because nothing lasts forever.

 

[Taylortwocities]

That some double sockets (and plugs) overheat is presumably just because nothing lasts forever

Yes, and many things are made to a price. So, while it may comply with the requirements of BS1363 at the point of certification, it may not be able to do that forever.

 

[JohnW2]

Yes, I know you are saying what some other people believe. However, what I am saying is that - ... if people believe a double socket must not be loaded with two 13A loads because the socket is only rated for 20A then to prevent two 13A loads being connected by Mr.Public it must follow that the socket should be protected by a 20A OPD.

Yes, in turn, I realise that is what you are saying - so, indeed, there are two different things being talked about here ...

... what I've been saying (recently in this thread) is that, in the case of the 20A switch, some people appear to be concerned if/when the current flowing through conductors connected to the supply-side terminals may carry more than the 'rating' of the switch (and/or of the circuit's OPD), even if (because of the loads and/or fuses downstream of it, current flowing through the switch will not exceed its 'rating' - so, as I said, if they applied that logic, they would presumably have the same (actually greater) problem with a single socket 'rated at' 13A on a 32A circuit, wouldn't they?

Why double sockets are said to be tested only to 20A, I have no idea.

I'm sure you do! They are "said to" be tested at 20A since that (14A + 6A) is the test current required by BS1363 to confirm compliance with the minimum requirements of that Standard.

That some double sockets (and plugs) overheat is presumably just because nothing lasts forever.

To some extent, but it does seem that 13A plugs and sockets are not as 'fit for purpose' as one would hope, since it does not seem all that unusual for them to show signs of disliking prolonged us at their 'rated' current - I don't recall many such problems with, say, 15A plugs (not that there were probably any 15A loads around!).

There is also the issue of that ancient MK document I have often posted (the source of which no-one seems to have discovered) which, despite the 26A 'rating' appears to say that continuous currents above 22A (if I recall correctly) through a double socket can result in significant damage (I seem to recall mention of 'fire risk'). I'll see if I can find, and re-post, it.

Kind Regards, John

 

[JohnW2]

.... There is also the issue of that ancient MK document I have often posted (the source of which no-one seems to have discovered) which, despite the 26A 'rating' appears to say that continuous currents above 22A (if I recall correctly) through a double socket can result in significant damage (I seem to recall mention of 'fire risk'). I'll see if I can find, and re-post, it.

Here you go ... this was posted in the IET forum in 2009, and purported to be a direct quote from the then current MK catalogue. It does, admittedly talk about very long periods of continuous very high currents (such as would probably never be seen in domestic installations) - but, as you'll see, it says that 22.3A (for an unspecified period) could cause thermal damage and potential cable insulation damage, and that 24A caused 'significant' heat damage at 43 hours and after 75 hours could result in thermal damage "sufficient to cause significant damage that would lead to the very real potential of fire." However, as I said, these durations of continuous very high loads would virtually never be seen in domestic installations ...

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 permissible 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-outlet 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.

Kind Regards, John

 

[winston1]

So we are back to my suggestion of using 2 singles rather than a double for the OPs oven and hob.

 

[JohnW2]

So we are back to my suggestion of using 2 singles rather than a double for the OPs oven and hob.

It might be wise but, in terms of what I posted, only if one had an oven which drew 13A constantly (which none get anywhere near doing) for very many hours. As I said, those durations of continuous high current they mention simply don't happen in domestic situations. The fact that they don't say anything about continuous currents below 22.3A suggests that there should not be any problem with domestic usage.

 

[DetlefSchmitz]

The times I had a socket go brown and give off a fishy smell were when I had electric fires keeping the room warm most of the time. I don't think it had anything to do with single or double sockets though. I believe that once the pins become tarnished the problem just accelerates and there can only be one outcome.

 

[JohnW2]

The times I had a socket go brown and give off a fishy smell were when I had electric fires keeping the room warm most of the time. I don't think it had anything to do with single or double sockets though. I believe that once the pins become tarnished the problem just accelerates and there can only be one outcome.

Indeed, as I recently wrote, most of the problems reported tend to major on thermal damage around the vicinity of the L pin/fuse and, as I said, I doubt that, in the case of a double socket, how much current is, or is not, going through the other 'outlet' has much impact on that.

Kind Regards, John

 

[bernardgreen]

most of the problems reported tend to major on thermal damage around the vicinity of the L pin/fuse

I seem to recall the test a socket had to pass was to carry 20 amps for a certain length of time with no evidence of any damage due to heating.

I wonder if the test could be carried out using a plug that did not have a heat generating fuse link. After all it would be unfair ( on the socket ) to fail it because of het generated external to the socket being tested.

 

[JohnW2]

I seem to recall the test a socket had to pass was to carry 20 amps for a certain length of time with no evidence of any damage due to heating.

Not quite. BS1361 does not seem to say anything about "evidence of damage", but merely that, with the specified test current (14A+6A = 20A in the case of a double socket) there should not be more than a 52 K temp rise within 4-8 hours (see note below) - which I imagine would not be enough to result in any visible damage ...

I wonder if the test could be carried out using a plug that did not have a heat generating fuse link. After all it would be unfair ( on the socket ) to fail it because of het generated external to the socket being tested.

I think it's only sensible to test the socket+plug combination together, since there would be no point in having a socket which, in some hypothetical situation, could pass the test but which could not pass the test when the (only available type of) plug was plugged into it.

In the case of a socket which includes a fuse (e.g. a triple socket) that fuse is to be replaced by a solid link for the temperature rise test.

Kind Regards, John

 

[garash]

Thank you. I am attaching a photo of my electric 'set up'. Does this make any difference to anything said. I appreciate all the advice.