cooker switches

[Fred]

Hi,

About a week ago there was an interesting thread about someone looking for a vertical cooker switch with integral socket. I wasn't sure if anyone was still watching that thread, so thought I would start a new one.

Some time ago I was looking for a vertical plate with socket and all I could find was the one listed on the TLC web site. Like the other poster, I didn't buy it because it was ugly! I'm pleased to hear the manufacturer has made it prettier.

What is the general feeling about these switches with sockets? Are they seen as a bad thing? IIRC they are supposed to be used for loads of 5A or less. Does this limit their usefulness?

I suppose you could use it for a food processor or similar low-current kitchen appliance but presumably you cannot use it for heavier loads, such as a kettle, toaster, or a vegetable steamer. Or does diversity mean that big loads for short periods are ok?

The old thread suggested taking a socket on a spur from the cooker switch. Is this within the regs? I have seen a double socket spurred off a cooker switch; that can't be right surely?

I wanted to ask: where should the cooker switches be positioned? Are they there only to isolate the cooker if you are cleaning, repairing, or replacing it? Or are they also to switch off the cooker in an emergency (i.e. it catches fire)?

The reason I ask is that I have an electric hob and an electric oven next to each other. I have two switches: one to the left of the hob and one to the left of the oven. The switch for the oven is behind the hob. I'm wondering if this is bad? Is there a risk of steam from the hob getting into the switch? Would I be able to reach over the hob to switch off the oven if the oven caught fire? Should I be thinking of relocating the switch for either of these reasons?

Are there any rules on how far away the switch should be from the appliance?

Is there any reason to have the large switches or is it that a double box gives you more room for the larger cable?

TIA

[John Rumm]

You can use them for any load you like - there is no limitation.

The 5A bit comes from when making a diversity assessment for the circuit

- that it is unlikely that the socket would add more than 5A sustained load.

Yup. In fact the 32A MCB and 6mm^2 cable means its more than man enough for anything you can plug into a socket.

Can't see it being a major problem. Its slighty unconventional. You can have a double socket spurred from a 32A radial or ring designed for normal sockets. Fault protection is provided by the MCB at the circuit origin, and overload protection by the nature of the load (i.e. just one individual socket fitting (even if its a double)) and that assumes you have dropped a cable size or two for the spur. So in general nothing bad is going to happen. However use common sense. If that double socket was likely to power a washing machine and dishwasher, then the chances of getting nuisance trips on the cooker increase.

Both. They should be within 2m of the device the control.

Having a switch over a hob is not ideal - not least from the point of view of the steaming that it may get.

Yes - guidelines certainly. The OSG (copied from 16th edition text) says "A circuit of rating exceeding 15 A but not exceeding 50 A may supply two or more cooking appliances where these are installed in one room. The control switch or cooker control unit should be placed within two metres of the appliance, but not directly above it. Where two stationary cooking appliances are installed in one room, one switch may be used to control both appliances provided that neither appliance is more than two metres from the switch."

Most of the switches with socket are double box sized. Hence they make switches alone that will also fit that form factor. The depth of the box is perhaps more important since it makes wiring with heavier grades of T&E easier.

[Fred]

Thanks. I guess the key word here is "sustained". A toaster or kettle on for a brief period would be ok.

I was thinking about moving the switch from behind the hob but reading the guidelines you posted, an alternative may be to remove that switch all together and use one switch for both the hob and the oven.

I don't know about that; the big switches I have seen are vertical but switches with sockets always seem to be horizontal, hence the other poster's difficulty in finding a vertical switch with socket.

Thanks again.

[John Rumm]

Yup.

Its part of a game of statistics really - averaged loads over time. Its why you can stick 15kW (65A) of cooker on a 32A circuit, and rarely if every have a problem in a domestic setting. (most cookers will pull less than 20A most of the time)

Yup, that is not an uncommon way of doing it.

[Huge]

The evening of the day we moved into this house, we had every light in the place on while we rushed from room to room. After a couple of hours it tripped the RCD, plunging us conveniently into darkness in a house where we weren't sure where the fusebox was, didn't know where the piles of boxes and furniture were, didn't know our way round in the dark and weren't sure where the torch was. Sigh.

Still, that was better than the morning, when we arrived to find no electricity at all. (It had stood empty for some months and water had got into the *non-submersible* connector for the cesspit pump and tripped the main house RCD. Still, at least the removal men thought it was funny, watching me bail out the cesspit with a bucket on a rope to get to the connector. Bigger sigh.)

[Owain]

Diversity is not applied to lighting circuits, for that reason.

The plot of The Towering Inferno confirms what happens when the electrician cuts corners :-)

Owain

[John Rumm]

One of the reasons I like to give any circuits outside their own CU and RCD etc. It may not remove the possibility of needing to bail out the cesspit, but at least you get to choose the time, and know the shower should be working when you are done! ;-))

[Huge]

Which it now has. It was originally just rubber insulated cable just under the lawn. It's now SWA with it's own CU and RCD at the house end, and an IP66 junction box (with a green "ON" neon on it) on a little post (*) at the cesspit end.

(* It was buried to start with, but I got sick of digging it up to troubleshoot faults.)

[John Rumm]

They had tried it in this house when we moved in... turned all the downstairs lights on, and they all went off after 15 mins!

[Huge]

It's never happened again. Can you suggest a reason why it did?

Quite.

[ARWadsworth]

Which tripprd? The RCD or the fuse?

[Huge]

TBH, I can't remember, it was 20 years ago. And we have MCBs. I think it was the lighting MCB that tripped, not the RCD (which is a whole house one). It's never done it again, so I always assumed it was a diversity problem.

[Light bulb over head!]

Definitely the MCB, because naughty me bought a larger one to replace the downstairs lighting one, to find that I'd been outthought by the designers, because the bases aren't compatible. It's still in the cupboard, somewhere.

[ARWadsworth]

Well if you have never had all the lights on again:-)

Or a lamp blew, that would take out the MCB.

BTW, If you want a bigger MCB let me know. I'll probably have one (you can have it for free).

[Huge]

Quite.

Troo.

Naah, thanks but like I say, I bought one, but you have to change the base (socket, whatever, the bit inside the CU it plugs into) but because it never happened again, ICBA to do it.