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.

--
Mike Barnes

On Wed, 18 Jan 2012 14:52:40 +0000, Mike Barnes wrote:

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.

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 ....

In article ,
Mike Barnes writes:
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.

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.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Mike Barnes wrote:
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.

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

In article ,
Mike Barnes wrote:
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.

Get a decent electrician.

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

http://www.tlc-direct.co.uk/Products/MKK4892.html

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

--
*I'm planning to be spontaneous tomorrow *

Dave Plowman London SW
To e-mail, change noise into sound.

Mike Barnes wrote:
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.

maybe a changeover relay?

The Natural Philosopher wrote:
Mike Barnes wrote:
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.

maybe a changeover relay?

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

--
Chris Green

In article ,
(Andrew Gabriel) writes:
In article ,
Mike Barnes writes:
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.

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.

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

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel :
In article ,
Mike Barnes writes:
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.

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.

That looks good, thanks.

--
Mike Barnes

Ebay 260829508456 LEGRAND Bath Sink Dual Switch. 20 Amp rated
incidentally. £4.48 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.

On Jan 18, 2:52*pm, Mike Barnes wrote:
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.

--
Mike Barnes

You could use a two way light switch to control a couple of 15 amp
contactors.
You'd have to mount them in a box etc.

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

--
Adam

On Jan 18, 8:20*pm, "js.b1" wrote:
Ebay 260829508456 LEGRAND Bath Sink Dual Switch. 20 Amp rated
incidentally. £4.48 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.


You should saw the joint out with a hacksaw blade to avoid damaging
the tank.
Immersion heater comes out no problem then,whatever's been done.

On Wed, 18 Jan 2012 14:52:40 +0000, Mike Barnes
wrote:

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.

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

On Jan 18, 8:41*pm, "ARWadsworth"
wrote:
Do you always have to cut all the post you are replying to?

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.

js.b1 wrote:
On Jan 18, 8:41 pm, "ARWadsworth"
wrote:
Do you always have to cut all the post you are replying to?

I think that is directed at me?

:-)

That was my point.

--
Adam