Kitchen Wiring Diagram

[ban-all-sheds]

Why is a double socket a maximum load of 13A?

 

[OwainDIYer]

In fact in a kitchen I would suggest not having more than 1 double socket on a 2.5mm 20A radial, as you do not know how appliances will be distributed around the kitchen

That's a bit of a waste, using a 20A radial for a max load of 13A.

Colin C

A double socket has a max load of 20A. And it would be quite possible to have 2 x 3kW appliances plugged into it (although probably full load only for short periods).

If you have more sockets on the same circuit you end up with American
wiring where householders learn what combination of appliances and outlets don't trip the breakers!

Yes it is wasteful, that's why the ring final circuit was designed after the War!

 

[ban-all-sheds]

No, it was designed as a quick'n'dirty expedient fix to the problem of suddenly increasing demand for socket-connected loads at a time of a copper shortage.

If ring finals were any good don't you think that more countries would have them by now?

Why has every country in the world without a British colonial connection stuck to radials?

 

[skenk]

They were designed to save copper, no?

Economising on copper is just as important now, if not more so, than back then.

As Owain says, a ring is good for a kitchen and the perfect solution for someone who doesn't have money to burn on multiple radials.

Different countries have their own way of doing things - the east stick to chopsticks, not impressed by our knife and fork, does that mean cutlery is rubbish?

 

[ajrobb]

Instead of junction boxes and FCU (fused spur) connections, you might want to consider accessible 20A isolator switches each feeding a single concealed socket. If you have a concealed switched FCU adjacent to each appliance, you won't be able to isolate them in an emergency.

 

[mikhailfaradayski]

A double socket has a max load of 20A.

Not that i've looked closely at the back of every socket, but i don't recall any being rated at anything other than 13A.

I wonder if anyone could post a picture of a socket back marked at 20A or some other number?

 

[OwainDIYer]

I think it's in BS1363, although MK Logic are good for 2 x 13A. There is also the factor on a ring circuit of point loading / unbalanced ring to consider, although that's not an issue on a radial.

 

[ccam108]

My mistake, I'm sure I was informed on here that a double socket outlet is only rated at 13A total. I have since found that MK DSOs are rated at 13A per socket, 26A total, however, Contactum DSOs seem to only be rated at 13A total (that's how I understand the, extremely ambiguous, "rated current" statement in the datasheet).

Surely there is a real danger here - not simply of the ability to plug 26A of load into a DSO potentially only rated at 13A, but of the total ambiguity between manufacturers as to whether it is indeed safe or not, and I'm willing to bet that not a single member of Joe Public is going to look up datasheets for his particular brand of accessories before doing so!

Colin C

 

[ban-all-sheds]

They were designed to save copper, no?

Economising on copper is just as important now, if not more so, than back then.

Not at the expense of safety.

As Owain says, a ring is good for a kitchen and the perfect solution for someone who doesn't have money to burn on multiple radials.

Owain is wrong - a kitchen is about the worst place possible to have a ring, assuming it's for appliances, a ring is a very imperfect solution for supplying multiple large loads concentrated in a small space, and "money to burn on multiple radials" is a ridiculous comment - why does there have to be multiple ones?

Different countries have their own way of doing things - the east stick to chopsticks, not impressed by our knife and fork, does that mean cutlery is rubbish?

I don't think that trying to draw parallels between eating implements developed in countries with no means to product cutlery in sufficient quantities and engineering decisions made by national electrical regulatory bodies in industrialised countries is going to profit you much.

 

[skenk]

Ok, a 4mm radial will do the same job as a 32A ring but it's more expensive to buy and more hassle to work with than 2.5mm. I'm not saying it's not an option but if you're quoting for someone on a tight budget, often a ring is the easiest option.

There's no safety problems with a correctly installed ring, just what do you think is the problem with having a few large loads on it? The CPD will operate before there is any danger. In my experience this hardly EVER happens in a typical 2 or 3 bedroom flat.

Am I right in thinking that BS7671 is used in many places around the world as a standard to work to? So maybe there ARE rings installed in loads of other countries!

Yes, if the ring is broken it could, potentially, cause a problem (anyone have experience of this because I would genuinely like to see what happens to a single 2.5mm cable used frequently at ~35 amps?) but there is a multitude of dangers of a bad installation - insulation behind diy downlighters for example.

 

[plugwash]

There's no safety problems with a correctly installed ring

The catch is in the "correctly installed" bit. Correcting installing a ring means more than just checking Zs/ring continuity/etc. It also means determining where the likely heavy loads are on the ring and how that will impact the balance of current in the ring. Afaict such analysis is almost never done. The closer the CU is to the kitchen the more of a concern this is.

The CPD will operate before there is any danger.

Depending on how load is distributed it is quite possible for almost all the load to go down one leg of a ring. That means on a badly designed ring you can easilly get into a situation where one leg is consistently overloaded yet the breaker never trips.

 

[mikhailfaradayski]

I think it's in BS1363, although MK Logic are good for 2 x 13A. There is also the factor on a ring circuit of point loading / unbalanced ring to consider, although that's not an issue on a radial.

I think it might be, but then again, it might not be. Maybe thats why i'm not making a bold statement of 'how it is' when i don't know for certain

Would still be interested to see a photo of the markings on back of a 'none 13A' socket outlet!

Any takers?

 

[mikhailfaradayski]

in a modern house with modern minded folk, how likely is it that 2 x 13A devices would be plugged into the same socket?

Not saying it can't happen, but i've never seen it in a domestic setting.

Can anyone cite any real examples?

 

[mikhailfaradayski]

Instead of junction boxes and FCU (fused spur) connections, you might want to consider accessible 20A isolator switches each feeding a single concealed socket. If you have a concealed switched FCU adjacent to each appliance, you won't be able to isolate them in an emergency.

Although not an emergency, I had this recently - washing machine failed whilst full of washing and water.
It has been plugged into a socket directly behind. The whole lot is under a worktop, sat on lino. Even though im not a small chap, i couldn't shift it with my finger tips.

What do you do after moaning about the complete F-Wit who allowed this install to happen?

IMO opinion, appliance-based emergencies are less frequent than a blue moon. I have never experienced this and over a few years of posting to a few forums, i have only ever heard one person give one example of such an event, making the idea of local emegency switching a bit redundant.

However, access to the appliance's fuse, whether FCU or plug top is important, over counter switches do not cater for this problem

 

[Chri5]

in a modern house with modern minded folk, how likely is it that 2 x 13A devices would be plugged into the same socket?

You can get 3kw toasters and 3kw kettles, and yes they could sit side by side and use the same d/socket