isolator switches to fixed kitchen appliances

[No.15]

Evening all.

I am having a brain fart regarding isolator switches to fixed kitchen appliances - mainly because I've never seen one (and the wholesalers are shut now). I'd be if someone could explain how they are wired to an unswitched socket.

Also for the following scenario would I need to put in a blank front plate and back box at the bend in order to keep within permitted cable routes?
- a kitchen ring circuit runs from a switched socket above the worktop, drops vertically down then bends to go horizontally to an unswitched socket, which has a vertical cable running to its isolator switch above the worktop and a horizontal cable running to the next unswitched socket etc.

Apologies for being ignorant - I need a bit of help from people who have the experience/ brains! Thank you.

 

[KFORDHUNTER]

Basically mate you should spur off the switched socket above the worktop into a 20a double pole switch, then feed the unswitched socket via this, you can then isolate the fixed appliance without having to move it out or remove the plug, you do not need a box on the "bend" as you are zoning horizontally and vertically with your 20a dp and unswitched s/o, just make sure you keep the cables straight with a nice 90bend.

Oh and don't forget, mark the switch and unswitched as "freezer, washing machine etc" that way you don't have to have it on an rcd.

 

[No.15]

KFH, you are fab! Thank you for the straight to the point answer.

I was thinking of isolator switches as being similar to light switches. Feel much better now

 

[tony.towa]

What I tend to do is replace the twin backbox, behind the twin socket, with a combined twin and single (you just have to extend the hole a bit) and then extend the final ring circuit so it passes through the supply side of the 20amp double pole isolator. I then run a single 2.5mm2 T&E to the socket outlet below the worktop level.
The isolators must be marked with the appliance they are supplying.(Had to be done under 16th)
The RCD/RCBO protecting the original final ring circuit will obvioulsy also protect the appliance socket outlet.

 

[greekislandlover]

Oh and don't forget, mark the switch and unswitched as "freezer, washing machine etc" that way you don't have to have it on an rcd.

I am not sure of this point, and would welcome more info.

Are we saying that in a kitchen only the socket outlets need RCD protection, and that we can run a separate ring for appliances without RCD protection provided that they are marked isolators feeding dedicated (marked) unswitched sockets? Do cookers have to be on the RCD side or not if they have no socket?

Surely for that to be the case the cables would need to be buried >50MM and / or in metal earthed conduit? Even so, the installation is in the hands of an uninstructed person (or whatever they call numpties in the politically correct world) so surely the RCD is necessary?

Just batting ideas about here - I'd love it if you could run all of those RCD tripping appliances on a proper supply!

 

[tony.towa]

My interpretation is that all will require RCD protection unless it is a dedicated circuit specifically for one appliance. This, to me, means a circuit run from the CU to the point of connection and not a spur off a final ring circuit. If I have got this wrong then I am sure that there are others here who will put me right.

 

[sparkyork]

hi matey, to be honest in this day and age id stick to having everything on an RCD, if it can go wrong it generally does is what ive found! so it comes down to how you 1st fix it really, if you had a big enough board you could run seperate circuits to each appliance, or you could fit a multi grid switch setup, supplying your appliances. or as part of your ring main have your FCU's as part of the ring and spur out of these to single unsw/sockets, or take the ring main to a local cupboard next to the appliance and put a surface mounted plastic box in. i prefer the last method me self, as you can get to the socket if you need to rather than it been behind the appliace, or feed the surface socket from either of the other options.

ps the multi grid switches look the mutts nutts but aint that cheap with buying yokes etc.

rich

 

[Carter]

BS 7671: reg 411.3.3 allows for an exception...

In a.c. systems, additional protection by means of an RCD in accordance with Regulation 415.1 (ie I delta n = 30mA, trips within 40ms @ 5x etc.) shall be provided for:
(i) socket outlets with a current rating not exceeding 20A (ie not just 1363 standard s/outlets) that are for use by ordinary persons....

An exception to (i) is permitted for:

(a) socket outlets for use under the supervision of a skilled or instructed person...

(b) a specific labelled or otherwise suitably identified socket outlet provided for connection of a particular item of equipment.

I've seen ready engraved sockets and FCUs marked up for "Fridge" "Washing Machine" etc. Bung one of those on and you'll be fine.

 

[KFORDHUNTER]

To be honest i think i have confused myself in my above reply, if you are spurring off the original ring main i think you would have to have the circuit rcd protected regardless of what the sockets are marked as, i think it has to be a designated circuit marked at one point, ie freezer to get away with the rcd, but to be honest these days i only say one thing to all customers, rcd oh and get a brew on, so thats two things.

I always rcd everything now, sod it.

Remember the rcd is there to protect you and your kiddies

 

[jimes]

do you guys not just use switched fuse spur to control unswitched socket under work top?

 

[KFORDHUNTER]

do you guys not just use switched fuse spur to control unswitched socket under work top?

No no and thrice no, if u use a switched fuse spur to feed an unswitched socket you will have 2 fuses in line, no discrimination mate, the 20a dp switch removes this problem, or you can have a switched fuse spur but u must feed a flex outlet plate instead, i prefer this method as when the fuse goes you don't have to drag the fridge out, but i am just lazy

 

[jimes]

theres lots of them out there, dont think ive seen a kitchen with dp iso's. Whats wrong with 2 fuses?

theres loads out there, never seen a kitchen with dp iso's except cooker. Whats wrong with 2 fuses?

 

[No.15]

I would use isolators instead of FCUs where there's a whole bank of fixed appliances - water heater, extractor fan, flue fan, dishwasher, fridge, microwave, hob etc. A grid of switches looks better (did someone say mutts butts?!) than a row of FCU plates.

I guess if there are two 13A fuses in series then one of them is going to be surplus to requirements - save the planet!

 

[greekislandlover]

I take the discrimination point, but how often does it happen that the washing machine fuse pops first? Doesn't your average 60898 pop faster than the plug top fuse, and is more likely to go than the washing machine fuse in the event of a fault?

Anyways, it's not us that has to drag the thing out to change the plug fuse in any case!

 

[sparkyork]

it is a good one this really, most companies ive worked for have put FCU in as part of the ring and come off these to a socket for an appliance either behind the appliance or in a cupboard next to it, and like you say ive never had to go out to replace a blown plug top fuse or fuse in the FCU it normally does take the 60898 or 61009's out instead. may be a different case for the older 1361's or 3036's.

on the multi grid switch's as well, although the main appliances will be fed from 20 A dp isolators fed from a ring main circuit, interistingly items such as fans or extractors have always been fed from a FCU (grid style) as part of the same grid switch.