# Max current on a two plug socket - appliances

#### Johnking

In my kitchen there is a dedicated ring circuit which serves the plugs, into which we have washing machine, dishwasher, tumble dryer, kettle, microwave and toaster. I noticed that the two laundry machines are plugged into a dual socket outlet which has been positioned specifically for this purpose. But I've read elsewhere that such outlets are rated at 13A max. The two appliances are rated such that the max draw would be about 20A. Is this problem?

Supplementary question. I'm moving the two machines to a new location and the socket there is on a spur. What issues apply here that are different to the ring socket in the kitchen?

Each socket can only supply 13 amps max regardless of how many outlets are on the socket. The circuit however can handle a lot more depending on how it is wired.

It is generally accepted that the maximum load on a twin socket outlet on a ring final circuit is 20 amps. But a twin socket on a spur can only supply 13 amps.

But they are only officially tested to 13 amps aren't they? I know the ones I have fitted have always said 13 amps max on it.

Dedicated to half a dozen items seems a bit of a contradiction but I know it is common to run conductors in parallel and/or ring finals to a grid switch feeding a kitchen or utility room. In the main the grid switches are rated at 20A and one has to question using them to feed 26A but personally I see little problem even if not strictly correct.

The problem with a 20A grid switch is getting two 4mm cables into the terminals is near impossible so it's common to use two 2.5mm cables and feed both end switches linking switch to switch so forming conductors in parallel of equal length.

If there is any other connection other than the grid switch it becomes a ring final.

Depending where you read the current from a double socket does seem to vary but personally only one item would worry me and that's the tumble drier. The rest do not draw max current for long enough to worry about so as long as tumble drier is on it's own socket I would not worry.

OK, so I need to get a second spur put in, otherwise I would have the tumbler and the washer drawing >13A on a single spur. Is that right?

Yes, have them on separate spurs to single sockets.

Do I need an electrician to do it, or am I allowed to?

But a twin socket on a spur can only supply 13 amps.

Why is that? If there is a 13A fuse in the way ?

It should be noted 2.5mm cable can carry 27A if installed correctly

There does seem to be some strange advice lately -
Each socket can only supply 13 amps max regardless of how many outlets are on the socket.
Sockets like anything else cannot supply amps.

There does seem to be some strange advice lately -
Each socket can only supply 13 amps max regardless of how many outlets are on the socket.
Sockets like anything else cannot supply amps.
Even given that it's Friday evening, that one seems a little on the pedantic side

Kind Regards, John

But they are only officially tested to 13 amps aren't they? I know the ones I have fitted have always said 13 amps max on it.
I understand that the BS1363 temperature rise test is undertaken at 20A total (IIRC, 14A from one outlet and 6A from the other, which seems a little odd!). You will be aware of an enormous amount of debate (not much helped by a conversation I had with a tech support guy at MK) about this issue. As has been said, I think that the most common view/belief is that the max total load for a double socket is around 20A - although some, like you, feel it is 13A.

As I always say, I don't know how/why this situation has been allowed to exist, since I'm sure that it has never dawned on most of the general public (who never see what's written on the back of one, even if it was clear!) that a double socket cannot safely serve two 13A loads (i.e. 26A total).

Kind Regards, John

But they are only officially tested to 13 amps aren't they? I know the ones I have fitted have always said 13 amps max on it.
I don't know which make you have fitted, but dual socket-outlets are tested for temperature rise at a total of 20A. Each individual socket-outlet has to be capable of carrying 14A.
They are 13A socket-outlets, and however many are included in a 'device', they are still 13A outlets, so a twin or dual has to be capable of carrying 13A in each outlet, bearing in mind the limitations due to temperature rise will limit the time for which a dual outlet can carry 26A.

They are 13A socket-outlets, and however many are included in a 'device', they are still 13A outlets, so a twin or dual has to be capable of carrying 13A in each outlet, bearing in mind the limitations due to temperature rise will limit the time for which a dual outlet can carry 26A.
I have asked many times why that is the case (and no one knows).
The only part in a socket which would be vulnerable to loads of over 13A (or 20A) are the rather thick pins and the rivets which join the pins to the prong assembly - nothing else would be subject to both 13A loads.

So, it must be the rivets.
Why do they not use rivets capable of handling 26A - or do they?

The 20 amp maximum for a double socket would make sense looking at the way some of them are assembled. The last two failures I have replaced ( brand un-known ) had failed where the terminal tube was riveted to the bus bar between the two socket terminals. The tube was slightly discoloured by heat while the bus bar had obviously been over heated.

Back in the 1980s the GPO ( or BT ) limited all 13 amp sockets to a maximum load of 9 amps. There were exceptions but only in special circumstances and only certain manufacturer's plugs and sockets could be run above 9 amps. ( MK if I recall correctly )

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