Mixing ring mains in the kitchen

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I've done a lot of searching about this and mainly come up with positive reasons for doing this but can't find any definitive rules or regulations regarding this.

My kitchen is being refitted soon. I'm rewiring the existing ring main in the kitchen (currently on the "downstairs" fuse) to relocate the sockets and to remove the existing spurs (on switches - not FCU's) to where the old appliances were.

I'm toying with the idea of using a grid panel for the new built in appliances - microwave, dishwasher, cooker hood, boiler and 2 x fridge freezers. I could quite easily tap this in to the existing downstairs ring main but could equally as easily connect this to the upstairs ring main (obviously relabelling the appropriate fuse in the main consumer unit). This would move some of the heavier current draw appliances to the lesser utilised upstairs ring. The cooker has its own dedicated feed anyway.

This would mean all switched sockets at worktop level would be on the downstairs ring along with the tumble drier and washing machine (lower power energy efficient units), the dishwasher, microwave, fridge freezer(s), extractor fan and boiler would be on the upstairs ring via the grid panel / 20A DP switches and fuses.

Both ring mains are already protected via a 30ma RCD in the consumer unit.

Any rules against this arrangement ?

Cheers
 
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Well for starters, grid switches are typically only rated to 20A, so not suitable for a ring.

You would be better off getting an electrician on board and pulling in 2/3 new 20A radials for the appliances. You will then, as you've mentioned, need to fuse down the extractor and boiler. This can be done with local FCU's or plugs and sockets.

If new circuits is not an option, I would forgo the grid switches, and go for a dedicated kitchen ring.

I dislike the idea of the upstairs ring feeding kitchen appliances, but if it's labelled properly, there's no problem with this
 
Why don't you have a couple of new circuits installed and make the downstairs part of the existing socket circuit in the kitchen redundant?
 
No rules, It's entirely personal choice.

You may have difficulty and unnecessary hassle wiring two circuits and many appliances into a grid switch.
Why bother with it?

I prefer the cooker hood on the cooker circuit.
 
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The route the cables run from the consumer unit would me a huge amount of redecoration (including a newly fitted en-suite) and recently decorated bedroom. All flooring is P5 chipboard as well so a pain to get under (they built the upstairs partition walls on top of this too !).

We could go with a run of SWA from the fusebox to the kitchen but would prefer to use the existing wiring available in the kitchen. I have the ceiling down in there so have full access to both ring mains.
 
Well for starters, grid switches are typically only rated to 20A, so not suitable for a ring.
The Wiring Regulations only require the cable to be rated for 20A, so why are you holding the switch to a higher standard?

You won't be switching anything like 20A through it anyway.
 
No rules, It's entirely personal choice.

You may have difficulty and unnecessary hassle wiring two circuits and many appliances into a grid switch.
Why bother with it?
The idea is to use the grid switch fed (part of) from the upstairs ring only for the six built in appliances but keep the rest of the kitchen on the downstairs ring (no wiring to the grid switch)
 
No there are no rules to say you should not use the second ring.

There one problem which may need redressing.
The whole idea of two RCD's is that if one trips due to a event in a room it will not also plunge the occupants into darkness a simple emergency lamp will redress this and in real terms it would depend on natural light in the room anyway. The rules are open to interpretation.

I have seen houses where the rings are side to side rather than up and down which makes a lot of sense as the amount of cable used is reduced so the loop impedance is also reduced.

This is the other problem when extending any ring. First you need to find out the length of the ring either by enquiry or by measurement to ensure the volt drop is not exceeded. You are permitted 106 meters of 2.5mm² which will with a incoming loop impedance of 0.35Ω result in a centre of ring impedance of 0.94Ω.

But with any alterations you need to complete the minor works certificate so no real difference to any other alterations.
 
As far as grid switches go if they feed a single device be it a FCU or a socket then the fuse in the FCU or plug limits the output so the only rule is no longer than 3 meters from the point it leaves the ring to the fuse. In real terms un-fused spurs are often longer than 3 meters 433.2.2 has been debated a few times as to if it applies to ring finals. Many feel it does not.
 
The appliances on the grid switch are split 50/50 over both sides of the kitchen (galley style).

My thought was to use a 20A labelled DP switch to a 13A fuse on the grid for each of the appliances which then feeds a 2.5mm2 spur to the "hidden" single socket behind the cupboards/units.

In reality the sockets will more than likely be accessible through the cupboard next to the appliance although I may put in false cupboard backs to these (or we will fill the cupboard up with junk) so I'd like a more obvious way to isolate these appliances in an emergency.

I realise they would then be double fused - I'm not bothered about this - if a fuse blows then generally there is a good reason for this and it should be investigated.

As for the grid switches being unsuitable for connection into the ring mains, from the research I've done, it would be no different to looping through the cable from a 13A socket in a ring - these are rated to 20A - the 2.5mm2 cable is rated to 20A - I'm using the switch as part of the ring main loop - not to switch or break the ring main.
 
As for the grid switches being unsuitable for connection into the ring mains, from the research I've done, it would be no different to looping through the cable from a 13A socket in a ring - these are rated to 20A - the 2.5mm2 cable is rated to 20A - I'm using the switch as part of the ring main loop - not to switch or break the ring main.
The grid switches are fine on a ring - just unnecessary in my opinion but up to you.
 

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