Current electrical regs - and Kitchens

[Roger Mills]

We are planning to convert a built-in garage into a kitchen - since it's bigger than the extisting kitchen (which will become a utility room) and we now have a separate detached garage.

Can some kind soul please tell me what the implications of the latest electrical regs (17th Edition, or whatever) are likely to be?

The current kitchen has a dedicated cooker feed - which I plan to divert to the new one - and has fixed appliances (fridge, dishwasher, etc.) plugged into 13A sockets on one of the ring mains. All circuits are protected by circuit breakers in the CU - but not RCDs. There are plenty of power outlets in the old garage, which can be moved around to suit.

One kitchen firm we've talked to is telling us that each appliance now needs a dedicated feed (presumably RCD protected?) so that if one trips it doesn't take the rest out. Is that correct? If so, that may mean replacing the CU - 'cos there aren't any spare ways or any RCD protection at present. If this is the case, what are the implications for the rest of the house?

Any informed comments will be greatly appreciated.

[BigWallop]

Just the fridge and / or freezer is best on a separate radial circuit. That way they stay on if the rest of the kitchen sockets go into fault. Also, and obviously, Electric Cooking Appliances are best on their own radial supply.

[David Hansen]

On Sun, 16 Nov 2008 11:40:03 -0000 someone who may be "Roger Mills" wrote this:-

No.

The existing garage ring circuit (I assume it is a separate one to other circuits) will be modified and thus becomes to all intents and purposes a new circuit as it will need to be tested properly for things like ring continuity. This will need to have an RCD. This can either be fitted in the existing consumer unit, if it has enough space, or can be fitted external to it (not as pretty as an new consumer unit, but cheaper).

It may well be sensible to run a non RCD fitted circuit for fridge and freezer. This may be possible without a new consumer unit by re-arranging the existing circuits.

[Fred]

I thought all outlets required a RCD? Are there exceptions? I know lighting for one but light fittings are not normally regarded as outlets.

[BigWallop]

The final ring can be protected with RCD at the consumer unit.

[cynic]

The 17th edition is in force now so forget what the requirements are likely to be on a job starting after July 12008, they are applicable to your new work. The most important new requirement to you is for ALL circuits with cables concealed at less than 50mm depth to be RCD protected unless protected by enclosing in earthed metal conduit or similar. It doesn't matter whether they serve sockets or fixed equipment. You "may" provide non RCD protected circuits for such as a freezer by using labelled socket outlet but the earthed steel conduit of sheath requirement remains unless you can see the cable or it is more than

50mm deep in the wall, floor or ceiling. The requirement of every appliance having its own circuit is a fantasy of the firm you spoke to but is is useful to spread the loads across a number of circuits to minimise inconvenience in the event of a fault and "some" circuits such as cookers and water heaters do need individual supply. The implications of the changes are not to be lightly covered here and you should buy a copy of the regs and on site guide or go to your local library to make full reference to the details.

[Tim S]

Fred coughed up some electrons that declared:

No... All socket outlets (with some tiny exceptions) "are required to be RCD protected at 30mA" which is subtly different.

Generally, the minimum number of RCDs deemed acceptable for a house these days is 2: see the so called "17th edition CUs", eg:

'm filling mine with RCBOs, one per circuit, except for heating (boiler + 3 immersion backup heaters, which will be one RCBO "submain" and 4 MCBs (or even one submain fuse and 3 MCBs + RCBOs, haven't decided). 16A x 3 for heaters and 6A for the boiler. The latter is more practical than 4 circuits from the main CU in my house, and I don't care if the heating trips out as a block - in fact in some ways it's preferable with my setup. There'll be means to isolate say a faulty immersion heater so the rest of the system can stay working.)

HTH

Tim

[<me9]

I have a 20a radial running in plastic trunking on the opposite side of the wall (in the garage) feeding the freezer (via labelled socket) and one or two other things(via fused spurs & flex) that I don't want to risk disconnecting.

I presume it would meet 17th edition, the wiring isn't visible, but the trunking is.

[John Rumm]

RCD protection for most circuits using concealed circuits without depth or shielding protection.

No, its twaddle. There is an argument for providing a dedicated circuit for freezers however. It would often be simpler to RCD protect these as well these days, however doing so via a RCBO might be a preferable way.

Main equipotential bonding will need to be brought up to scratch (if not already). RCD protection can be added as an afterthought. You may be able to get single module RCBOs for your brand of CU - that would allow you to add RCD protection to the relevant circuits and maintain good discrimination without the cost of a complete new CU. Using separate secondary enclosures is also possible but messy.