LED lighting circuits, dimmers and drivers advice

[gorselands]

Hope someone can help


I am doing an extensive refurbishment of my kitchen including lowering the ceiling.

The room dimension is L 24 ft. (7metres) x W 12 ft. (3.6 metres) x H 10 ft (3.2 metres) approx.

I want to fit dimmable LED down lights on separate circuits so they can be switched independently..

I understand from reading:

I need to work on about 35 lumens per square foot going to 75 lumens over the work surfaces. To calculate the number of lights (about 20?) and because of the height of the ceiling a beam angle of 40 degrees.

The dimmer switches need to be leading edge.and have a minimum load though I’m not sure what this should be.

Do I also need drivers (transformers) and if so do I need one for each bulb or would one driver handle all the bulbs on one circuit, or a number of circuits?

I estimate 7 or 8 switches to include the downlights and accent lights.

Can anyone recommend a suitable grid, dimmers and drivers?


I would really appreciate some help and advice on what I need. I don’t want to ‘spoil the ship for a ha’porth of tar’ as the saying goes. Though I appreciate it's going to cost more than a 'ha'porth'!

The lighting shops and some sparks I have spoken to don't seem to have much of an idea as the technology is fairly new.

Thanks

Mike

 

[PrenticeBoyofDerry]

You don't need tranies/drivers.
You can go down the 230v route, use dimmable LED GU10, compatible dimmer switch for lamps (why you want to dim kitchen lights, I don't know)
The dimmer switch will have a min and max rating, so your lighting chains need to be inside that value.
What lighting shops have you been to?
Go to a good electrical wholesalers, they will offer you advice.

 

[gorselands]

Many thanks for the reply.

The kitchen will be a kitchen/diner so wanted to dim some of the lights, switch some off, and have some feature lights. Probably over egging the pudding. I did think of the GU10 dimmable + dimmer though these are more expensive and I need 20 so was wondering if there was an alternative using standard led bulbs. I will look at the dimmable bulbs again. The two national wholesalers I visited weren't very forthcoming and one suggested low energy strip lighting was the new thing.

Again thanks

Mike

 

[PrenticeBoyofDerry]

Even if you use ELV you still need the lamps, tranies to be dimmable, a compatible dimmer switch and switch and tranies to have a suitable rated output.

 

[gorselands]

Thanks for getting back,

So you are saying that if I got a non dimmable led bulb I would still need a driver for each lamp + dimmer module and switch - not priced the dimmers but it looks as though it's probably six and two threes, so easier to find a suitable led dimmable bulb. Presumably if they are described as dimmable they have the circuitry built in to the lamp.

Thanks again

Mike

 

[PrenticeBoyofDerry]

If you get non-dimmable lamps, you don't need a dimmer switch as they wont dim!
If you want to dim them, everything needs to be completable for dimming!

As far as drivers/transformers are concerned, they need to be rated suitably for the output of the lamp or lamps they are connected to.

 

[SimonH2]

personally I'd not go for separate fittings and bulbs - that way you get bulbs compromised to fit in fittings plus the scope of someone sticking a halogen bulb in later and potentially causing problems with load and/or heat.

A friend has just stuck 15off Halers H2 in his living room, in addition to the four he had in the bathroom. Personally I think a grid of spots in the living room looks pants (as does the all-white 'clinical' colour scheme) but he likes them. They dim very well with Varilight dimmers.
Not cheap, but nothing LED will be cheap - unless you buy rubbish that will need replacing quite soon anyway.

Lastly, I'd suggest you get everything together and do a quick knock up (wire everything as it will be, with a plug for a supply) and check that the lights work with your dimmers before everything is installed and it's a) more work, and b) potentially decor damaging, to alter.
Obviously, if you are having multiple similar circuits then you can get by doing one at a time and just check that you have all the combinations covered. Eg, if you are having circuits with (say) 2 and (say) 5 lights, then do a knock up with 2 lights, then add the extra 3 so you can check both configurations.
You might also consider taking the opportunity to check all the lights before they are stuck in the ceiling, and all the dimmers before they are in the grid.

 

[gorselands]

Thanks guys for the helpful replies. A good idea to test the circuits before final fix. I agree that a large ceiling can end up looking like a landing strip so will be leaving two pendants in place. Also agree that the complete lamp and fitting would be a handy solution. Problem with that is if the light isn't right. I was planning to try one or two bulbs to work out what is best. Watts, beam angle etc, The ceiling is 11 feet high so whatever is fitted has to reach the floor and give the right light. The recommendations so far are pretty confusing. Some 480 lux are three watt others recommend 7 watt and so it goes on. I decided the only way was to suck it and see, buying one or two bulbs until I found one that suited. (or I could just stick to the striplights that were in before I started!!) As you will have guessed - pretty much an LED novice.

Any more thoughts or advice are very much appreciated.

Again, many thanks,

Mike

 

[SimonH2]

The problem with a bulb is that there is a very limited envelope available for a GU10 (or similar) and that's going to severely restrict cooling options - hence a high power compact bulb is either going to be restricted in output compared to a purpose built LED fitting, or it's likely to be of questionable reliability through inadequate cooling. A purpose made LED fitting can use the whole of the outside as a heatsink which will make quite a difference. Also, some of the LED fittings have a separate driver which means the driver circuit components aren't as exposed to the heat from the lamps - which contrary to what some people think can be considerable.

You are right that the whole LED thing is confusing. Some of the 'quality' manufacturers are apparently looking towards having some standards so that end users can easily compare specs - but needless to say, those peddling 'cheaper' options are keen for the confusion to remain so they can more easily peddle their wares.

 

[gorselands]

Thanks for the reply. The complete fittings will be a squeeze at best. Only brought the ceiling down about 6" as didn't want it to look as if it was sat on the top of the window frames.

I didn't think 240v. dimmable LED needed a driver - it has some circuitry built in, or is that a mini driver? Driver only needed for 12v. Or are driver and transformer separate things?

Finally I thought the LED bulbs gave off little heat and that leaving a gap round them would be sufficient. Most of the better bulbs have heat sink built in. Another factor is that the Haler units you mention are about £50.00 and I would need 20 !!

Getting more uncertain as to what to do.

Cheers

Mike

 

[PrenticeBoyofDerry]

230/240V LEDs lamps don't need drivers. Read my first post in reply.
What you have brought up though is another issue regard depth in the ceiling void and the ventilation gap that will be required for the cans.

 

[SimonH2]

Being pedantic, 240V LEDs do need a driver - but it's part of the fitting.

When you use a bulb (eg GU10) then the driver is all in the same package with the LEDs - and exposed to all the heat. On the Halers (and another one I've seen) the driver is small unit external to the lamp housing - with the Haler it's attached, with another make someone here suggested it's on a short lead which makes locations more flexible. In basic terms driver means pretty much the same thing as transformer (as long as you are talking about the small switch mode electronic "transformers").

It's true that LEDs have much less heat to get rid of, something like 7 to 8W for the Haler H2 vs about 50W for a halogen, but they still need to get rid of it and at a lower temperature than the halogen. The halogen lamp and fitting will run at a fairly high temperature (large temperature difference = rapid heat dispersal) - a temperature that would very quickly destroy both the LED chips and their electronics. Thus the LEDs need considerably more heatsink area.

Incidentally, I've seen an LED lamp for a lighthouse - to replace the big halogen lamps. From memory, the LED section itself was well under an inch cube - but the heatsink for it was something like a foot high !

 

[gorselands]

Thanks again SimonH2. I'm now seriously considering putting the old fluorescents back up.

Given that the area is 26sq metres with a ceiling height of 3.25 metres do you have any thoughts as to the number of lights, output, wattage and beam angle?

Doing some re-tiling at the moment and the next job is the ceiling so I have to make some decisions before that goes up.

I wonder how many LEDs the lighthouse lamp had? If we take that heatsink as a norm most domestic leds would be enormous.

Cheers

Mike

 

[bernardgreen]

Being pedantic, 240V LEDs do need a driver - but it's part of the fitting.

Super pedantic, a current controller

- but the heatsink for it was something like a foot high !

There are water cooled LEDs as well.

 

[SimonH2]

I wonder how many LEDs the lighthouse lamp had? If we take that heatsink as a norm most domestic leds would be enormous.

It was a custom design by a local firm that specialises in such things. Several "state of the art" high power chips on a lump of copper or alli. Only seen it once, briefly, and from memory the LEDs were crammed into a small space (giving the appearance of a massive LED something like an inch square). These were a lot higher output than any domestic lamp, from memory intended to replace a few hundred watt halogen bulb.

Given that the area is 26sq metres with a ceiling height of 3.25 metres do you have any thoughts as to the number of lights, output, wattage and beam angle?

Not really ! But at least with that height you have plenty of options - and should be able to avoid the "pools of light in the darkness" that spotlights usually produce.

Assuming it's the normal "worktops round the walls" sort of setup, I'd give serious consideration to putting lights along the undersides of the wall cabinets. It makes a big difference by lighting up the worktop without people creating a shadow on their workplace as normally happens with overhead (and especially central) lighting.

PS - I'm not averse to flouro strips myself for a room like a kitchen. Inexpensive, reliable, high output, what more could you ask for - apart from aesthetics.