Design - radial to kitchen

[Smugley]

I'm in the middle of a kitchen refit at the moment. The kitchen ring consists of 8 sockets and two fused spurs. I'm thinking of running an additional 4mm 32A radial to a four-gang grid switch with labelled 20A DP switches.

From the grid switch, four 2.5mm radials will feed four unswitched single socket outlets for washer, dryer, dishwasher and waste disposal. These sockets will only be used by the devices they are labelled for, and naturally will be connected with fused plugs.

Can you see anything wrong with this setup? Technically I was wondering whether the 2.5mm radials should be fused at the switch, but anything plugged in automatically cannot draw more than 13a. I haven't used grid switches before in this way but the intention is to reduce the clutter of multiple fused spurs on the splashback. It seems much neater but is this the best way to wire it I wonder?

 

[Hawk81]

personally i would not do it that way. I would be afraid of some1 changing the single socket to a connection plate and wiring an item in direct. Then you have a 2.5mm cable and 20amp switch backed up by a 32amp mcb. I have seen it happen. Others will probably disagree with me.

 

[Sparky Ninja]

I did an exact installation like this. But had a grid of switches, followed by a grid below of fuses. The all the appliances were wired directly and the appliances fuses were installed in the grid.

 

[Smugley]

I tend to agree that the fuse should be 'upstream' of the cable being protected rather than at the load end. Pity they can't make those grid switches with an integral fuse. The client is pushing for as little above the benchtop as possible. I think a compromise will be to put another grid or individual FCUs in the backs of cupboards, or perhaps downgrade the MCB to 20A which should be plenty for the devices attached.

 

[Mark42]

Hi Smugley. I believe that all cable runs should always be protected (I think that’s a regulation anyway, apart for short runs in bus bar chambers etc). Your initial arrangement would be effectively a reduction in CSA without protection. Obviously you know this and were uncomfortable with it, and that's why you posted in the first place!

I agree with Hawk that you never know what accessories might be replaced/added later.

But I like your grid switch solution: as you infer, it is neat and professional, and MK make some very nice pre-labelled 20A DP switches.

I have done a very similar thing in my own house, by supplying a grid panel from a 32A MCB on 4.0mm or 6.0mm, but having a grid fuse at the plate for each load, fitted with a 13A/10A/5A cartridge as required. But as you say yourself, this adds to the clutter, and grid fuses are not pretty (and are six quid a pop), but it’s still less cluttered than multiple spurs, and less cable pulling than multiple radials. This was for multiple IR wall heaters in my workshop, so aesthetics were less important.

And if you’re using 13A sockets as the final connection, the fuses would probably not discriminate properly, which is bad design.

Why not simply run the final circuits in 4.0mm? Then you can still protect the whole thing at 32A, and rely on each plug top fuse for appliance protection. Elegant, easy, and a happy client.

With a deep back box 4mm into grid switches is not difficult – I did a 3-gang one in 4mm in my kitchen only this morning.

 

[Smugley]

Cash-and-dash, that's a good idea, in fact I was leaning towards just making it a 2.5mm 20A radial with 2.5 all the way to each socket, which I think should be plenty to accommodate washer, dryer and dishwasher, even without taking diversity into account. Very unlikely these together would need more than 20A, but perhaps I'll do it in 4mm as you suggest, just to be on the safe side. As far as I can determine this is a safe configuration.

As you pointed out, I was also not happy about the lack of discrimination with having fused spurs to fused plugs.