I'm having trouble meeting all those critera for my wetroom... I
wondered if anyone might be able to recommend a source or make of LEDs?

Low profile = about 8cm or less depth from rimp to back, 6cm would be
better. Lots of free air in the void for cooling, just not that much
depth before it hits celotex.


I'd much prefer 12 or 24V constant voltage units rather than "comes with
its own obscure constant current driver that produces random voltages".

And IP65 or better is a requirement (technically I could get away with
IPx4 according to the regs) but this is going in Zone 1 on a low ceiling
(2m) over an open shower. That's why I want SELV 12 or 24V too - mains
may be permissible but it would seem to be a crap idea


Cheers,

Tim

In message , Tim Watts
writes
I'm having trouble meeting all those critera for my wetroom... I
wondered if anyone might be able to recommend a source or make of LEDs?

Low profile = about 8cm or less depth from rimp to back, 6cm would be
better. Lots of free air in the void for cooling, just not that much
depth before it hits celotex.


I'd much prefer 12 or 24V constant voltage units rather than "comes
with its own obscure constant current driver that produces random
voltages".

And IP65 or better is a requirement (technically I could get away with
IPx4 according to the regs) but this is going in Zone 1 on a low
ceiling (2m) over an open shower. That's why I want SELV 12 or 24V too
- mains may be permissible but it would seem to be a crap idea

CPC carry the Enlite range of LED downlights. IP44 at least and can be
dimmed. Flush mounted but mains operated.

--
Tim Lamb

On 16/08/2017 16:35, Tim Watts wrote:

I'd much prefer 12 or 24V constant voltage units rather than "comes with
its own obscure constant current driver that produces random voltages".

Can't be done.

LEDs need a constant current to work well. If you feed them a fixed
voltage, when they get a little warm their resistance drops. So they
pass more current, and get warmer. Quickly. Very much warmer. Bang
follows soon after.

Andy

On 16/08/17 21:37, Vir Campestris wrote:
On 16/08/2017 16:35, Tim Watts wrote:

I'd much prefer 12 or 24V constant voltage units rather than "comes
with its own obscure constant current driver that produces random
voltages".

Can't be done.

LEDs need a constant current to work well. If you feed them a fixed
voltage, when they get a little warm their resistance drops. So they
pass more current, and get warmer. Quickly. Very much warmer. Bang
follows soon after.

Andy

Please explain LED tapes

And the 24V striplights I have in my kitchen...

Also, there remains the possibility to put a localised driver on board,
but fed from 12 or 24V rather than mains.

On 16/08/17 21:00, Tim Lamb wrote:
In message , Tim Watts
writes
I'm having trouble meeting all those critera for my wetroom... I
wondered if anyone might be able to recommend a source or make of LEDs?

Low profile = about 8cm or less depth from rimp to back, 6cm would be
better. Lots of free air in the void for cooling, just not that much
depth before it hits celotex.


I'd much prefer 12 or 24V constant voltage units rather than "comes
with its own obscure constant current driver that produces random
voltages".

And IP65 or better is a requirement (technically I could get away with
IPx4 according to the regs) but this is going in Zone 1 on a low
ceiling (2m) over an open shower. That's why I want SELV 12 or 24V too
- mains may be permissible but it would seem to be a crap idea

CPC carry the Enlite range of LED downlights. IP44 at least and can be
dimmed. Flush mounted but mains operated.


Mains is no good (my requirement, not BS7671) - I am of the opinion that
230V cables on foil backed vapour barrier plasterboard 10" over my head
in a wet/steamy environment is a bit of a crap idea.

But thanks for saying CPC - I'll have a hunt around there - and RS...


Next stop - boat/caravan place where 12V and 24V are common... And
expensive, probably

In article ,
Tim Watts wrote:
voltage, when they get a little warm their resistance drops. So they
pass more current, and get warmer. Quickly. Very much warmer. Bang
follows soon after.

Andy

Please explain LED tapes

And the 24V striplights I have in my kitchen...

The source voltage is irrelevant. It's the current through the LED which
matters. The cheap way is to use a series resistor to restrict the maximum
current - but there are more efficient ways of doing it.

Also, there remains the possibility to put a localised driver on board,
but fed from 12 or 24V rather than mains.

The driver doesn't have to be close to the actual LEDs. But you may want
one which is safe for your application, as regards voltage.

--
*My dog can lick anyone

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

On 17/08/2017 09:49, Tim Watts wrote:
On 16/08/17 21:37, Vir Campestris wrote:
On 16/08/2017 16:35, Tim Watts wrote:

I'd much prefer 12 or 24V constant voltage units rather than "comes
with its own obscure constant current driver that produces random
voltages".

Can't be done.

LEDs need a constant current to work well. If you feed them a fixed
voltage, when they get a little warm their resistance drops. So they
pass more current, and get warmer. Quickly. Very much warmer. Bang
follows soon after.

Andy

Please explain LED tapes

https://learn.adafruit.com/rgb-led-strips/schematic

suggests an inline resistor, like Mr Plowman suggests. Efficient that is
not.

And the 24V striplights I have in my kitchen...


I could guess.

Also, there remains the possibility to put a localised driver on board,
but fed from 12 or 24V rather than mains.

Sure. That's probably the best bet - install your own constant current
supply.

Andy