High current two way switch?

[Mike Barnes]

A friend has two immersion heaters which mustn't be switched on simultaneously because the wiring isn't up to it. He'd like a switch to select one or the other. I explained that a two way lighting switch would be logically effective but couldn't take the current. I suggested a 13A socket and two plugs. He'd prefer a switch but I can't find a two way switch for anything heavier than lighting. An electrician is doing the job but has gone home scratching his head.

[Jethro]

Probably totally unsafe, but how about an old-fashion knife-type switch (like the one in hammer horror films). Pretty certain they can be connected to toggle between two loads ....

[Andrew Gabriel]

MK do a switch for exactly this purpose. It's designed to switch between an immersion heater at the bottom of the cylinder, and one at the top, and is labeled "Bath" and "Basin" (or something like that) depending how much hot water you want heated up.

There are two switches on the switch plate, the other one being ON/OFF.

[Theo Markettos]

Does it need to be on a standard faceplate? There are plenty of DPDT rocker switches from the usual components places (Farnell, Maplin, etc) - some take

20A or more. Just needs appropriate mounting.

Presumably he wants A, B or off, rather than just selecting A or B? There are switches with a central off position. As the current position isn't always obvious, maybe get one with a built-in neon indicator.

Theo

[Dave Plowman (News)]

Get a decent electrician.

Grid switches have commonly had a two way 20 amp option.

Other makes too. And probably some plain old single gang plate switches if you do a search.

[The Natural Philosopher]

maybe a changeover relay?

[tinnews]

Farnell/CPC do a range of cam switches which provide A-OFF-B with hefty current ratings.

[Andrew Gabriel]

Part number K5208, or K5207 if you want a neon indicator too.

[Mike Barnes]

Andrew Gabriel :

That looks good, thanks.

[js.b1]

Ebay 260829508456 LEGRAND Bath Sink Dual Switch. 20 Amp rated incidentally. =A34.48 delivered. LH switch handles "ON" & "OFF". RH switch handles "Bath" & "Sink" dual elements.

It seems ironic such a dated product function is still available today ("heat enough for a bath or a just sink"), but they serve a useful purpose. Immersion elements do fail and the recent crop of generic safety elements seem to have atrocious reliability. Many tanks have the option for dual element and having "some hot water" is a lot better than none. Elements are cheap, trashing a big copper tank trying to get an old one out rather expensive - particularly if Boss White'd in place in a hard water area.

So if replacing a tank, particularly for an elderly relative, requesting a dual element option is a good idea.

No connection with the Ebay seller, but have used Legrand before - often better design & aesthetics than Honeywell MK's bricks - and better quality control to boot.

[ARWadsworth]

Do you always have to cut all the post you are replying to?

[Owain]

Economy 7 immersion heater timers can also control two heaters, from one supply, with either/or operation.

Owain

[grimly4]

Some electrician you have there if he doesn't know about bath/sink switches. Does he jangle as he walks?

[js.b1]

I think that is directed at me? I often post on the move when waiting on something for a few mins, balancing the laptop on my lap, using Google over 3G, so tend to whack a comment out & [CTRL]+[SHIFT]+[HOME] & [DELETE]. Will remember in future.

Harry, Re cutting out the seal on the tank - absolutely. A screwdriver or chisel can be good too, may take a few minutes picking out the seal, but it can avoid a lot of unproductive brute force & frustration.

[ARWadsworth]

:-)

That was my point.