The Lemon Fool

You used to be able to get devices which switched printers/screens etc ON when the PC was powered up.

I want the opposite.

I want a device which will supply power to a socket, but will switch the first socket OFF when power is drawn from a second socket. Is there such a thing? My googling skills have failed to find it.

It’s for a summerhouse which has a single 13A supply, a 2kw heater and a 3kw kettle. I’d like the heater to automatically switch off when the kettle is switched on. I guess it could be done with a power diverter switch, but does anyone know of a device which will do it automatically?

Gryff

Haven't come across the gadget for which you are looking but if you were willing to compromise on the automation a bit you could employ a changeover switch to energise either the kettle socket or the heater socket alternately. Failing that a small DIY project to detect the mains voltage applied to the kettle (rectifier + opto-isolator) then use that to switch a relay supplying the heater-socket.

Chris

gryffron wrote:
You used to be able to get devices which switched printers/screens etc ON when the PC was powered up.

I want the opposite.

I want a device which will supply power to a socket, but will switch the first socket OFF when power is drawn from a second socket. Is there such a thing? My googling skills have failed to find it.

It’s for a summerhouse which has a single 13A supply, a 2kw heater and a 3kw kettle. I’d like the heater to automatically switch off when the kettle is switched on. I guess it could be done with a power diverter switch, but does anyone know of a device which will do it automatically?

I'm wondering if you could do it with two of the original devices that you've mentioned....

If you had two of those devices, and in a separate junction box you installed two contactor relays, you could have the power from one of the 'powered when the main device is on' sockets go to one of the contactor relays, to open-circuit the power to the opposite equipment.

On the opposite equipment, you'd also then have one of those original devices, but where that 'powered when the main device is on' sockets then goes to the *other* contact relay, to open-circuit the power to the first equipment.....

Both contactor relays would need to be suitably rated to be able to switch both relatively high-powered devices....

This all seems very complicated on the face of it though - would it not be simpler to introduce some sort of 16A RCD somewhere in the summerhouse power circuit, that would simply break the power to the whole socket-circuit if someone's daft enough to forget, and they try to power up 5kw of load?

In addition to the above, is there perhaps a simpler opportunity to fix the wiring for both the heater and the kettle in such a way that their 240V plugs are only then available near a *single* 240V socket, and as such would then clearly need 'swapping out' each time either one of them is used?

Cheers,

Itsallaguess

Itsallaguess wrote:is there perhaps a simpler opportunity to fix the wiring for both the heater and the kettle in such a way that their 240V plugs are only available near a *single* 240V socket, and as such would then clearly need 'swapping out' each time one of them is used?

This solution appeals to me.

kempiejon wrote:This solution appeals to me.

Or maybe a dedicated cloud-based server monitoring the state of each device (kettle, heater) using the Internet of Things and issuing directives aimed at limiting the current consumption? Would that perhaps be simpler?

kempiejon wrote:

Itsallaguess wrote:is there perhaps a simpler opportunity to fix the wiring for both the heater and the kettle in such a way that their 240V plugs are only available near a *single* 240V socket, and as such would then clearly need 'swapping out' each time one of them is used?

This solution appeals to me.

Dump the kettle. Stop drinking tea/coffee and switch to something else? Ah, hang on, that might require a beer fridge ...

dealtn wrote:Ah, hang on, that might require a beer fridge ...

No problem. Fridge plus heater probably won't melt a 13A fuse. Problem solved, brilliant!

If you have WiFi in the summer house a simple solution would be to use a smart power strip or smart power plugs. You can build routines like 'turn off plug a, wait 1 second, turn on plug b'.

I use these: https://www.amazon.co.uk/TP-Link-SmartT ... 383&sr=8-3

I use the Amazon Alexa app for building routines like 'turn on phone charger plug, wait 4 hours, turn off phone charger plug', although you might want to explore alternatives like google if you don't use alexa.

It would also allow you to pre-warm the summer house, check that you remembered to turn off the heater...

csearle wrote:

kempiejon wrote:This solution appeals to me.

Or maybe a dedicated cloud-based server monitoring the state of each device (kettle, heater) using the Internet of Things and issuing directives aimed at limiting the current consumption? Would that perhaps be simpler?

if you do go down that route
- don't re-invent the wheel have a look at: https://www.openadr.org/

- sd

If you only had one plug socket and no fancy adapters then the problem is solved!

monabri wrote:If you only had one plug socket and no fancy adapters then the problem is solved!

Indeed that is also what Itsallaguess suggested in his last paragraph. Certainly seems the cheapest and most reliable option (but not as much fun to talk about over that cup of tea).

.......and if it's a double socket or strip of sockets.......there are 3 pin plugs available that are switched & with indicator lights. I know it's not the automatic process that you are looking for but it's a very cheap & simple method of achieving the result you are looking for.

Or a changeover switch which would feed either of two sockets but not both.... not automatic but inexpensive and foolproof?... https://www.ebay.co.uk/itm/172741552700?hash=item283832ea3c:g:Jn8AAOSwyWZZSiod

V8

88V8 wrote:Or a changeover switch which would feed either of two sockets but not both.... not automatic but inexpensive and foolproof?... https://www.ebay.co.uk/itm/172741552700?hash=item283832ea3c:g:Jn8AAOSwyWZZSiod

Thwack! Chris

csearle wrote:Thwack! Chris

Oops. And yours is a quid cheaper

V8