using a 12v switch to operate a 240v appliance

[xelaris]

A proper wire wound transformer works both ways. If you supply a 12V - 230V transformer with 230V it outputs 12V. Conversely if you feed it with 12V it outputs 230V.

As long as your existing 12V supply is AC, You could feed this into an isolating transformer to switch the relay coil to switch a 230V fan etc.

As the relay is fed through an isolating transformer, even if the relay fails catastrophically and the switching voltage ends up on the coil supply, all you'll get at the shower is a maximum of 12V which is deemed to be safe.

Something like this coupled with a 230V relay and base would do the trick.

Thanks a lot for all the useful info....
This will require some extra work and more importantly, more time to review my electronic knowledge...

 

[xelaris]

apologies for my recent outburst ....at times one gets the impression that the world is spinning too slowly for all the wrong reasons - this happens in all fields and disciplines (this time was the electricians....next the plumbers
)

 

[DaftPunk]

Unfortunately it's not quite straight forward, but isn't all that complicated and it will ensure your safety should things go wrong. If you get stuck, I'm sure someone on here could provide you with a wiring diagram.

 

[bernardgreen]

what do you mean by "electrically separated"?

In a relay there will be no insulation between the 12V and 240V circuits

So what is the "insulation breakdown voltage parameter" ( often 2000 volts or greater ) refering to. ?

Of course there is isolation between the contact set and the coil in a relay. ( There are some specialist relays where there is an inbuilt connection betweem contact set and coil but these are few and far between )

Same as the compact transformers for SELV door bell supplies that fit on CU bus bars. They are acceptable but ( in my opinion ) have more risk of insulation failure ( mains onto the SELV ) than the average correctly selected relay.

 

[viewer]

"The transformer does a lot more than simply feeding the fan....there is a radio, led lights, audio connectors, massager....., the shower has a steam facility"
Yikes
Would one of these help?
http://www.aliexpress.com/store/pro...d-receiver-31MHZ-433MHZ/507574_510233923.html

 

[ban-all-sheds]

right now I'm pretty clueless on how to use/connect this stuff

Then stop fiddling with it.

Not to mention to having to deal with all those Regs checks and limitations? Who's keeping down the evolution of domestic lighting? Greedy professionals perhaps?

Your attitude is wrong.

Presumably you have no intention of complying with the law, either?

the killing is the money made from of all these blockages and regs checks - which would not be needed (most of them) if 12v were made more available - innit? Just greedy pro don't want that cos' they'll lose - and we all are kept in the dark - literally.
The flashy technology seen on that link could be available for much less...instead it's a niche only for the well off - like a form of taxation to be paid for keeping the old regime going....

Go away.

 

[bernardgreen]

A proper wire wound transformer works both ways. If you supply a 12V - 230V transformer with 230V it outputs 12V. Conversely if you feed it with 12V it outputs 230V.

When running a transformer backwards it is advisable to de-rate to 50% of the power rating in the forward direction. This allows for the losses in eddy currents and resistive losses in the windings to be low enough to avoid over heating the device.

 

[xelaris]

"The transformer does a lot more than simply feeding the fan....there is a radio, led lights, audio connectors, massager....., the shower has a steam facility"
Yikes
Would one of these help?
http://www.aliexpress.com/store/pro...er-31MHZ-433MHZ/507574_510233923.html[/QUOTE]

I thought about something very similar: - in fact it is still an option:
http://www.google.co.uk/shopping/pr...=X&ei=ZBgcUYzXLKXK0AWTwoHQAg&ved=0CIkBEPMCMAU
....just and extra gadget as it will require a remote switch and a receiver....if I sort out the relay then I don't need any extra switches as there is one already incorporated in the shower...