Unusual lighting install in bathroom.

[LostInTheUnderflow]

I want to install lighting something a little unusual in the bathroom

4 leds in series.
Current driven 20mA, each led dropping around 2.5V.
Lots of them dotted around the bathroom, with wiring behind the tiles.
3mm Leds that fit between 4mm gap in tiles.
I have experimented with creating a jig, and angling them down at 45mm.
They are then to be potted and made waterproof.
Only little dots are going to appear out of the grout.

I plan on driving them from a 12V supply as the top rail and some transistors controlling the current to 20mA. The 12V supply and driver circuitry is to be situated in a safe zone. The power supply will be double insulated. The live side is to be protected by an RCD.
So I have no qualms about getting in the bath and knowing I am safe.
I am going to do this myself as I am not sure I could get an electrician to know what I want.
I am concerned about certification.
I may just enjoy the lighting, while I live in the house, then when I sell the house, drill out the leds and re-grout. Then disconnect the 12V supply.

What do you think about. Safety, and certification. Is this a notifiable job?

 

[toasty]

My concern would be the source of the 12v supply, you need to make sure the 12v supply is intrinsicly safe - i.e something designed for use in a bathroom and a supply whereby there is absolutley no chance of the mains appearing on the output. An RCD would be a very prudent investment too.

Regarding the leds, 4 in series off a 12v supply is fine, 20mA supply current seems reasonable, LEDs normally drop nearer 2v, so meaning you'd need a 200ohm resistor rated at a least 0.1watt. I can't see why you'd want to use a transisitor to regulate the current, seems a bit cimplicated to me.

Good luck

 

[333rocky333]

Where safety isolation is necessary, something like Medical grade power supplys, may be required.
These tend to have more reinforced insulation between the windings.

I think what your trying may need to be classed as a true SELV system to be classed as safe.
More so if the tiles are in zones 1 or 2

 

[ricicle]

you need to make sure the 12v supply is intrinsicly safe

Yeah - just in case those noxious gases from the bathroom try to combust

 

[LostInTheUnderflow]

I bought a Osram Halotronc Mouse, but I'm not sure it will do the job.

It seems to have an output that they describe as complex AC. I think the voltage is 12V RMS, but it is not a sine wave. This is OK for halogen lamps, but not for my setup.

Not sure what this would do if I bridge rectified it to DC.

What would be wrong in using any power supply that has the double square symbol for double insulated.

If not could I use an isolating transformer.

I have seen some very expensive supplies.

As far as the transistors are concerned, I do want to get more complicated. Firstly I could switch them on off all together and wire them through resistors. I may want to control them through a microcontroller and dim them / switch them automatically.

The tiles are in zones 1 and 2.

If you know of any supplies, then let me know.

Thanks for the help. I'm glad that you didn't just tell me that I was mad.