L v lighting quey

[cjard]

I like the idea of led lighting, so does the Boss who pays the electricity bill, and so does the building inspector and SAP guy.

I'm curious.. Are led lighting systems 240v all the way to the bulb or are there systems where there is a single, nice and efficient transformer near the CU and then all the lighting is low voltage?. Or is it a case that there are a small number of transformers, the switches operate at 240v on the transformers and that causes the lights to go on and off?. What's best value?
How can I ensure that I don't end up with bulbs that are all different in color after a few years of replacements? Are led prone to being all wacky shades and brigtnesses? What do I need to be able to dim led bulbs? A friend has rather nice touch sensitive infrared light switches that dim his halogens using he tv remote.. Do these exist for led lighting?
If I wanted switches that sense room occupancy and turn lights on (utility, bathrooms, halls etc) do I have to plan wiring for those specifically eg do they need their own power supply as well as the load they switch ? And finally, do there exist any lights that can come on after an adjustable delay? I'm thinking for floor level lighting in the hall, I'd like he ones nearest the bedroom door to come on first, then proceeding down the hall, just for the visual effect.. Essentially, one light illuminating would cause the next to come on; is it the sort of thing that is centrally controlled by a module/raspberry pi, or is there a way of daisy chaining lights together such that one sets off the adjacent ones? I realise that some of these questions are more electronics than electrics, just wondered if any sparks here had come across intelligent lighting systems in their pro work?

Just thinking around my lighting install and how to plan it

 

[bernardgreen]

You are taking on a massive design job.

LED lamps are good for energy saving and can be dimmed if the correct drivers are used. But dimming an LED does not change the colour, they remain the same colour but less bright. The change from bright white to soft warm glow that can be achieved by reducing the voltage to an incandescent lamp is not possible with LED lighting.

No matter how well you plan the lighting after living with it for a few months you will find things you don't like and thing you want to add.

If you have a clean canvas ( before decorating ) then my suggestion would be wire all lamp locations to a central point where an intelligent controller switches the power to the lamps as required. It adds cost of extra cable but gives the flexibility to change the way the lamps are controlled.

My main controller

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• bernardgreen
• 26 Mar 2015
• 3

and a slave relay module controlled by the main controller

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• bernardgreen
• 10 Mar 2015
• 4

Usimg ELV ( 12 volt ) for the switches on the inputs of the controller makes locating and wiring the switches much less work as alarm type cable can be used and chasing the walls for switch cables is minimised if not eleiminated.

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• bernardgreen
• 31 May 2014
• 5

A Raspberry Pie could be a suitable "brain" for the controller but would need interfacing to the inputs from switches, sensors etc and carefully designed interfacing to the relays controlling the mains voltages.

My controllers are my own design specifically to meet the requirements of this cottage. ( once a design engineer, always a design engineer ). It could be a nightmare for the next owner of the cottage.

I dim lamps by connecting two identical incandescent lamps in series which gives a nice warm light and requires no failure prone electronic dimmers.

 

[flameport]

or are there systems where there is a single, nice and efficient transformer near the CU and then all the lighting is low voltage?.

The issue with doing that is voltage drop - distributing 5V or 12V or similar voltages around a house will require substantially sized wiring, even for low power levels.
LED elements are constant current anyway, so there is nothing to be gained from one central fixed ELV supply.

 

[ericmark]

A white LED typically runs on about 2 volt but it's the current which is more important. The LED is rarely used as an lamp normally they are combined with other components for easy use.

So for a 12 volt lamp one could simply used 3 LEDs and a resistor the latter limits the current. But for 230 volt that resistor would cause too much heat so the control device is an electronic unit as a result the so called 230 volt LED can often run with anything for 150 ~ 250 volt.

Remember it's current which really matters so if you have 10 LED's of 350 mA each in series then if you have a device which controls current to 350 mA all will work well. These are called drivers.

However just to mess it all up some bulb manufacturers call any device used to run LED's drivers even if they are simply a voltage regulated power supply.

This means buying 230 volt LED's is easy but with extra low voltage it's easy to both get a miss match and have a unit which produces more heat than light. It has become a mind field trying to work out which lamps are energy efficient and which are not. Also the lumen rating is not helping as there are a few way to measure it and so 3W = 250 lm should show it's a reasonable but not always.

Colour is a real pain with both LED and CFL but using a CD and viewing the reflection works reasonably well. Some give off green, yellow, red as three separate colours and rely on our eyes to see it as white others give out all the colours of the rainbow. LED's tend to be better than CFL giving a wider range of colours and as a result are used by photographers they are nearly as good as the xenon flash tube. Colour temperature tends to be high 3000K called warm white but seems to me hotter than a 3000K CFL likely as because the CFL is a mixture of colours rather than complete range so although the electronic meters see the CFL as 3000K we see them as 2500K it is the LED's which are correct but we have got use to the measurement on CFL.

It really is a suck it and see with LED lamps. I swapped 10 CFL at 8W each for 10 LED at 3W each and the room was really too bright. But read the lumen that was 2500 lumen instead of 3800 lumen so it should have been darker.

 

[RF Lighting]

You would be best to wire your house as standard and then fit either direct to mains LEDs or have a transformer local to each lamp, although this offers very little advantage over direct to mains lamps.