DPDTCO switch for domestic mains

[PeterC]

In the loft there's a run of 2.5 FT&E that goes to a heater point in the bathroom. I'd like to leave the heater point wired in but would like a couple of sokets in the loft (inspection lamp, vac, that sort of thing).

Rather not have the chance of someone running a 3kW heater and 1400W vac via a 15A MCB, so wondered about a switch to mount in the loft to enable only one outlet at a time.

There are plenty of toggle or rocker switches that would do the job - I have some - but a metal toggle switch in a box...?

The only others that I've found are grid switches; I'd like something like a cooker point but with a suitable switch.

Any pointers please?

[Dave Plowman (News)]

Think you'll be lucky to find what you want - but does it have to be DP? If single pole a 20 amp two way switch will do what you want.

[ARWadsworth]

How about a simple 20A dp switch in the loft to feed the heater? When you are working in the loft then just turn the heater off with this switch.

Other options would be to use a contactor or as Dave Plowman has pointed out use a 20A 2 way switch (it would probably have to be a grid one though).

Cheers

Adam

[NT]

Its normal for the total possible load on sockets to far exceed the cable rating and fuse protection. This isn't a problem, and if you really plugged excessive loads in, first there's a safety margin in the cable, and second the 15A mcb would trip if the overload were significant and sustained. No switch needed.

NT

[Andrew Gabriel]

Or plug the heater in to a socket in the loft, which you unplug to use for something else.

[Tim Watts]

Dave Plowman (News) wibbled on Thursday 22 July 2010 13:50

Other than panel switches, it is an unusual configuration for an accessory and I don't think the OP will find one either...

Assuming the OP really does want DP, contactors might be an option.

[Bob Minchin]

A toggle switch mounted of a standard blanking plate fitted to a suitable deep back box. Don't forget to earth the box. You can get toggle switches with screw terminals. RS/Farnell/CPC etc

Bob

[Owain]

MK K5208 - it's actually a dual immersion switch, 2 switches, one for off/on the other for sink/bath, prevents two simultaneous loads

Owain

[NT]

If you really want to be strange and fit a selector switch, single pole is fine.

NT

[js.b1]

You have Type-1 MCB? Cor, I thought only I had stuff that old :-)

This is a non-issue unless you run the cleaner for 30-60min.

A 3kW heater will cycle on its thermostat, but assuming continuous that corresponds to 4400W or 18A which can be drawn for some time even on a Type-1 15A MCB or Type-B 16A MCB.

Type B

1.13 * In =3D > 1hr which is 18.1A for a 16A MCB. 1.45 * In =3D < 1hr which is 23.2A for a 16A MCB. 2.55 * In =3D < 1min which is 40.8A for a 16A MCB.

Hence even a seemingly meagre 20A protected radial can handle a lot of appliances with diversity. Conversely a short circuit of 5 * In (80A for Type-B 16A MCB) will cause near instantaneous

[PeterC]

OK, just actually had a look at it (I haven't used the heater for several years and had forgotten about the availability of the feed in the loft) and it's actually 20A! Given the details below - thank you - I reckon that I don't really have to worry.

Probably wouldn't do that now, but during the clean-up it was on for about

2 hours during one session.

OK, looks as if I don't need to worry about it. It's OK for me, as I'm aware of loadings etc., but I was considering future use by those who like

3 appliances in 1 socket.

Many thanks for the various suggestions - some good ideas if I do need to do this elsewhere.

[PeterC]

That was the tempting way as I have a few of those (also 20A relay, 40A SSR etc.).