Is this okay? Kitchen Isolation Grid Plate Diagram

[JohnW2]

This is how I read it too.

I'm glad I'm not alone!

I don't see why it's deemed pointless to have these switches, it makes a luxury job. .... Appliances should be conveniently isolated when required. ... Appliances can be accidently switched on without realising, the isolating switches can help to prevent this.

Views about this are clearly polarised, with quite strong views on both sides. In relation to your last point above, those who are 'anti' (not me, I'm essentially 'neutral'!) would say that the converse is also true - that, with switches, appliances like fridges and freezers can be "accidentally switched off without realising"!

The one thing which is clearly true is that, as flameport has said, to have all the major kitchen loads connected right at the very end of one leg of a ring circuit is not appropriate (and not compliant with regs, either).

Kind Regards, John

 

[JohnW2]

Would the longer length of cable serving the kitchen sockets serving perhaps a kettle, toaster occasional low power small appliances provide enough current once combined with the shorter cable?

Current from something connected to the ring divides between the two routes back to the CU in inverse proportion to the lengths of the two paths. Hence, if the load is, say, only 10% of the way along the ring, 10 times more current will go via the 'short' route than via the 'long' route - hence only one-11th (about 9%) of the current will go by the long path - and, more to the point, around 91% will go via the short route.

Don't most kitchen ring circuits have the potential to be 'unbalanced'?

Only if all the major loads are concentrated close to one end of the ring.

Has this ever been an actual problem anywhere?

The regulations and standard practices are pretty conservative, so one can often 'get away with' doing things which are not compliant with the regulations, but that doesn't mean that one should do it - nor, for example, that an insurer would necessarily settle a claim if they found that a fire had been caused by a wiring design that was not compliant with the Wiring Regulations.

Kind Regards, John

 

[flameport]

Don't most kitchen ring circuits have the potential to be 'unbalanced'?

Yes, it's a common problem.
If other loads were in use elsewhere and not all of the grid switched items were, the ring current would obviously be balanced better - but just having all of the large load items in one place means it will be unbalanced for most of the time.

would you rather a ring circuit wired in 2.5mm2 serving JUST the bank of switches?

I would not suggest anyone had such switches.
If someone insisted they had them, it would be done as a 4mm² radial with MK grid switches which can accept 2x4mm² in the terminals.

Has this ever been an actual problem anywhere?

No idea, but given the large numbers of installations it's very likely. Whether it would be noticed is another matter, as overloading 2.5mm² cable with a 32A load won't cause any obvious effects such as cable failure, smoke or fire.

 

[sparkwright]

It could be argued a ring that doesn't always have 'fixed' loads.

Where just sockets are fitted, and room changes inevitable, 'unfixed' loads could be moved about and plugged in very randomly.

Typical examples of such 'portable' appliances may include heaters and kettles.

 

[flameport]

The original intent of rings was that one should cover the entire house, most items plugged in would be low power and/or intermittent, and the only high power thing which would be left on for an extended period would be an electric fire up to and including 3kW.
Given that most people would not have more than one electric fire in each room, the load balancing idea still worked.
At the time, most of the high power kitchen appliances such as washing machines, dishwashers, tumble dryers and microwaves did not exist.

At some point relatively recently it became the fashion to start installing a ring for each floor of a house, one for the kitchen, another for a utility room and other nonsense including the garage, workshop, garden shed etc.
The original intent ignored, and inappropriate high loads concentrated in one place becomes inevitable.

 

[JohnW2]

... deleted .. hit send button by mistake!

 

[JohnW2]

It could be argued a ring that doesn't always have 'fixed' loads. ... Where just sockets are fitted, and room changes inevitable, 'unfixed' loads could be moved about and plugged in very randomly.

Indeed. It's impossible for a designer to design any sockets circuit 'properly' (as one could do if all loads were 'fixed'/hared-wired), since he/she has no control over what will be plugged into them - and that applies to both radials and rings. There's nothing unusual or unreasonable in having a circuit with, say, 8 double sockets, but there's also no law saying that someone feeling very cold might not have 16 fan heaters. The designer therefore has to make 'reasonable assumptions' (or guesses) as to how the circuit will be used. That's obviously less of a problem with the situation we're discussing, since most of the major loads are essentially 'fixed and known', and plugging things into other sockets will usually only be for brief periods (kettles, toasters, mixers etc.).

If one seriously overloads any sockets circuit (ring or radial), at least the protective device (fuse of MCB) will put a stop to it. However, with a ring circuit there is a specific problem, since the cable used is not rated to take the full current that the circuit is designed to supply (and would allowed to be supplied by the fuse/MCB). It is permitted to have a 32A ring circuit wired in cable rated to carry a maximum of 20A. The designer still has limited control, but can minimise the risk of the 'short leg' cable being 'overloaded for long periods of time' (which is what the regs say should be avoided) by not putting (m)any sockets close to the end of a ring. In fact, where it is logistically possible, one can completely avoid the possibility of any cable becoming overloaded by ensuring that there are no sockets within a certain proportion of ring length from either end of the ring.

Kind Regards, John

 

[ToastyToes]

I agree with everything else you have said, but it was not just "under the stairs" but, rather, "under the stairs in the kitchen". I took that to mean that the stairs encroached into the kitchen, so that the switches would actually be "in the kitchen" - which, if one is going to have them, is clearly the most appropriate place.

Kind Regards, John

As that will only be when it's broken, removing it from the housing is inevitable.

This is how I read it too.

I don't see why it's deemed pointless to have these switches, it makes a luxury job.

Appliances should be conveniently isolated when required.

Appliances can be accidently switched on without realising, the isolating switches can help to prevent this.

When I have finished using the washing machine or cooker I can safely isolate easily by the switches above the worktop.

Why would you want to leave these things fully connected if they don't have to be?

Thanks all for your inputs.

I understand the load would be very close to the CU which isn't ideal.
Equally I want to be able to easily access integrated appliances power supply.

What is the most common method to do so? Should I just install switched sockets as part of the kitchen ring above/below or in adjoining cupboards to the appliance to switch them?

Thanks
Theo

 

[securespark]

When travelling I like to switch things off.

When travelling I like to turn things on.

 

[securespark]

Joke aside, if you want to isolate an appliance in a hurry, why not use the MCB?

 

[JohnW2]

What is the most common method to do so? Should I just install switched sockets as part of the kitchen ring above/below or in adjoining cupboards to the appliance to switch them?

When it is done (and, as you have been told, it's not 'necessary' and some people seem to have quite strong views 'against it'), the 'most common method' is probably what you are proposing. BUT (because of the layout of the circuit and the location of the CU) with the bank of switches much closer to the centre of the ring - in which case the issue of potentially loading the 'short leg' of the ring doesn't arise.

Since that's not possible (without being silly and installing lots of 'unnecessary cable'!) in your situation, the best alternative would probably be what you have already been told - namely to use a 4mm² radial (rather than a 2.5mm² ring), and use decent grid switch modules (like MK) which can happily take 2 x 4mm² conductors. With such a radial, it doesn't matter where the loads are connected to it.

Kind Regards, John

 

[AndyPRK]

I can't see the problem with fitting 4mm cable, rather than 2 lots of 2.5mm cable.

Would this be regulation compliant?

4mm cable to the grid switch
2.5mm cable for the ring.
Both fed from the same 32A MCB

 

[ToastyToes]

When it is done (and, as you have been told, it's not 'necessary' and some people seem to have quite strong views 'against it'), the 'most common method' is probably what you are proposing. BUT (because of the layout of the circuit and the location of the CU) with the bank of switches much closer to the centre of the ring - in which case the issue of potentially loading the 'short leg' of the ring doesn't arise.

Since that's not possible (without being silly and installing lots of 'unnecessary cable'!) in your situation, the best alternative would probably be what you have already been told - namely to use a 4mm² radial (rather than a 2.5mm² ring), and use decent grid switch modules (like MK) which can happily take 2 x 4mm² conductors. With such a radial, it doesn't matter where the loads are connected to it.

Kind Regards, John

I can't see the problem with fitting 4mm cable, rather than 2 lots of 2.5mm cable.

Would this be regulation compliant?

4mm cable to the grid switch
2.5mm cable for the ring.
Both fed from the same 32A MCB

What about 2.5mm ring for kitchen worktop sockets and then separate 4mm radial to grid switches for appliance sockets?

 

[JohnW2]

What about 2.5mm ring for kitchen worktop sockets and then separate 4mm radial to grid switches for appliance sockets?

Sure, that's what essentially has been suggested, since we've only really been talking about the grid switches for appliances - it is that which (if you're having the switches) would be best on a 4mm² radial.

An alternative, of course, would be to have the grid switches on just their own 2.5mm² ring circuit (hence with both legs of the ring would be almost equal in length). That would almost be a 5mm² radial, but it might be slightly easier to implement, since one would only be having to deal with 2.5mm² conductors in the grid switch terminals.

Kind Regards, John

 

[ToastyToes]

Sure, that's what essentially has been suggested, since we've only really been talking about the grid switches for appliances - it is that which (if you're having the switches) would be best on a 4mm² radial.

An alternative, of course, would be to have the grid switches on just their own 2.5mm² ring circuit (hence with both legs of the ring would be almost equal in length). That would almost be a 5mm² radial, but it might be slightly easier to implement, since one would only be having to deal with 2.5mm² conductors in the grid switch terminals.

Kind Regards, John

Thank you John. You have been very helpful on a number of topics of mine.

I think I will run the grid switches on a separate ring and then have the conservatory and kitchen sockets on a second ring. (instead of having separate rings for kitchen and conservatory this balances things and still equals two circuits instead of three).

Thank you all