Where does the wire come from between LV spots?

possibly a daft question, but let's say I have 10 led spots in a room and I've designated one of them as the place whereabove the transformer will be stored.. For my first fix I've run the lighting radial in and out to the spot area, and a wire down to the switch so I can now power and switch the transformer..

But from the transformer to all the spots I'll have some wire, and I'm wondering does this come with the spot, does it come as a separate accessory i.e. A length with a couple of dedicated pre crimped plugs, or do I fit a length of 2 core 1.5 between them and strip/screw it to the spot housings? Does it depend on the type/brand of transformer/spot? Are there any install kits intended to make the job faster?

Usually each LED spot has it's own driver buit into it, or each fitting needs it's own seperate transformer.

Usually nowadays you just run a 230v supply cable to each light position.

This is the best and least complicated way of doing things. If you do this make you use sheathed cable with an earth wire present.

a transformer per spot? that's mental; there are somewhere in the region of 100 spots in the house.. sounds like it saves neither the planet nor my pocket

there's a dimmer in this system too, idea was to have a dimmable transformer and LEDs, and it be just the one transformer. I get why jo public in the street wants to buy an LED with integrated transformer so that he can just direct swap it for his GU10 halogen that's burnt out, but I wasn't thinking to have such a system..
..unless of course, such LEDs are nicely dimmable in which case it simplifies the wiring above the first spot somewhat..

I'll run 1.5mm T&E between all the spot positions, to keep the options open while I find out exactly what will be going in

cjard said:

a transformer per spot? that's mental; there are somewhere in the region of 100 spots in the house.. sounds like it saves neither the planet nor my pocket

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Are you under the impression that 12V uses less power than 240V?

I'll run 1.5mm T&E between all the spot positions,

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Why. That's using 50% more of the planet's copper than you need.

Chances are you will be getting 230v LED fittings, which won't have a transformer, yet each fitting will have a driver built into it.

You don't necessarily want 12v lighting - transformers can often pack up. If you had one central transformer for a room and it packed up then no lights in that room would work.

If you do think you will be having a central transformer (no one has that now) put it somewhere where it can be accesses easily. Chances are it will be too big to pass through a downlight ceiling hole.

EFLImpudence said:

Are you under the impression that 12V uses less power than 240V?

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No, losses aside, power is power regardless. It uses more materials to have a transformer per spot and introduces a greater recycling headache

Why. That's using 50% more of the planet's copper than you need.

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Are you under the impression that I'm using T&E with a CPC of identical CSA to the phase conductors?

Joking aside, it uses less copper than scrapping an inadequate cable and replacing it should something change in future..

sparkwright said:

Chances are you will be getting 230v LED fittings, which won't have a transformer, yet each fitting will have a driver built into it.

.

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What's the difference between a driver and a transformer, in LED lighting nomenclature?

cjard said:

No, losses aside, power is power regardless. It uses more materials to have a transformer per spot and introduces a greater recycling headache

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Ah, sorry, misunderstood which part was saving the planet.

Are you under the impression that I'm using T&E with a CPC of identical CSA to the phase conductors?

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Not sure what you mean.
You said you were going to use 1.5mm²; surely 1mm² is more than adequate.

Joking aside, it uses less copper than scrapping an inadequate cable and replacing it should something change in future..

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What does?

cjard said:

What's the difference between a driver and a transformer, in LED lighting nomenclature?

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The method of doing it at the time the definition was recorded.
(Running dispute on here)

Simply:
Transformer alters AC voltage.
Driver controls current.
http://www.voltimum.co.uk/articles/q-day-what-difference-between-lighting-transformers-and-drivers

sparkwright said:

(no one has that now)

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Apart from me in my bathroom - but that was due to a oversight and before I had LED's; but I agree having 1 transformer for all those spots lights will mean should it fail, you will have no lighting. Also are your spots going to be the replaceable MR16/GU10 type (Typical: MR16 12V / GU10 230v) or are they going to be a integral unit with their own driver in.

It is also worth mentioning that having one central transformer or individual transformers will have a power loss of it's/thier own on top of that of the LED spots should you be using the 12V MR16 type; thus being less efficient than that of integral LED units with their own drivers or 230V LED lamps.

cjard said:

What's the difference between a driver and a transformer, in LED lighting nomenclature?

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If I am correct, LED drivers are basically switch mode power supply's that put out a very tightly regulated DC voltage source that can cope with the very low wattage of LED loads. Proper and pure transformers such as toroidal transformers are less conmen these days in favour of switch mode power supply's that are often incorrectly called transformers, albeit that they often have miniature PCB mounted transformers in them for primary to secondary side isolation.

cjard said:

No, losses aside, power is power regardless. It uses more materials to have a transformer per spot and introduces a greater recycling headache



Are you under the impression that I'm using T&E with a CPC of identical CSA to the phase conductors?

Joking aside, it uses less copper than scrapping an inadequate cable and replacing it should something change in future..

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1mm T&E is the correct cable and not inadequate.

I am running 6 spots from a central 300va Toroidal transformer but its about 125 mm diameter, each fitting is up to to 3 metres away and I used 2mm two core wire desighned for that use.
Using smaller sized electronic transformers, you are limited on output lead length for eec reasons, sometimes as low as 1.5 metres though some larger 300 watt units allow 2 metres, the reason why suspended 12 volt wire track systems still mainly use Torroidal transformers.
However 12 volt led lamps are not living up to there expectations and appear prone to problems, so as yet Im still using halogen lamps via a Lutron dimmer

http://www.qvsdirect.com/2-core-low-voltage-lighting-cable-cut-length-sold-by-metre
( ps ignore the low voltage term)

It seems the lighting industry swaps names around a lot, switch mode power supply, pulse width modulated, drivers, electronic transformers, and the list goes on. When dropping the voltage we have a number of options, we can control the current which is a true driver, this means we can have loads of LED's all in series until the combined voltage of the LED's reaches the maximum voltage output of the driver. Save the planet wise that is likely the best.

However we can also reduce voltage and current in stages. First we reduce the voltage then we use a driver to reduce the current. Seems a little pointless but that is what we so with 12 volt spot lights. As to save planet it depends how the current is controlled. With AC can be resistor, capacitor, or full PWM driver, the latter uses far less power. But because we use drivers after the 12 volt supply we have to run in parallel so volt drop is not auto compensated for.

So for a 16/8" or 2" spot light it really does not matter if 12 volt or 230 volt it still needs a built in driver and the 230 volt version does not need a voltage dropper as well so may as well use 230 volt.

As to dimming the true driver and LED's in series is the best option you control the current to all LED's together. When using any driver remote from the dimming controller then some method is required so the dimmer talks to the driver, with 12 volt this is harder as the dimmer needs to talk to the voltage dropper then the dropper needs to talk to the driver. In the main the dimmer switch cuts the wave form and the driver reads the cutting of wave form as an instruction to reduce current fed to LED.

The problem is colour does not change when dimming so there is no ambience like with tungsten there is no red glow. So rather than pay twice the price for a LED with a driver which will dim you may as well just arrange 1/3 and 2/3 on two switches which gives three levels of light.

The LED is naturally directional there is no need for a multifaceted reflector (MR) or to limit the size to 16/8ths of an inch the unit may be compatible with MR16 but it is not an MR16. If you look at commercial LED lighting around 30% is sent down with 70% reflected off the ceiling this give a better spread of light. A fitting like this which reflects most of the light off the ceiling is doing the same as the commercial fittings and is likely the best way to use LED lights when thinking about planet saving. With a lamp aimed at the floor unless the floor is white most of the light is absorbed rather than lighting the room.

With the 2" spots only real way is to bounce off the wall assuming near white wall which means you need fittings which can be tilted to shine on the wall.

EFLImpudence said:

Not sure what you mean.
You said you were going to use 1.5mm²; surely 1mm² is more than adequate.

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I thought you were recommending I get a 2 core cable (LV, no need to earth the fixtures), hence thinking that you were looking to save 50% copper by omitting a 1sqmm CPC (which wouldn't be 50%)



Re the rest of the replies, this is one aspect of building a house that I'm growing incredibly weary of - every question leads to more questions!


OK, so in my hallways I like the idea of having spots deliberately arranged to pake a pattern on the floor. Saw it in a hotel in belgium and really liked the way they had set 1 spot, then 2, then 1 then 2 etc.. made a nice mesh of light and dark spots

In rooms, I'm putting spots in the ceiling with the aim of providing downward lighting of the significant objects in the room e.g. in the bathroom the're a spot above each "appliance", in the lounge a u shaped couch and coffee table are lit, dining room table, kitchen island and so on.

I'm also putting in circuits for wall lighting mainly because the missus doesnt like downward light because it does something funny with her contact lenses. These wall lights will likely be uplighters and hence better suited to providing diffuse light


Good point about the LEDs just dimming and not providing a glow - i kinda wanted the glow. I'm looking at using ultrawarm white LEDs to try and get it, but does anyone have any specific recommendations for bulbs?

Regarding wire length/distance to next spot - does CSA have a bearing on this?

Regarding bulb options.. so in the true driver sense eric, do 230v leg bulbs come with such a driver built in, or is that the situation where I'm buying one bigger driver and using it on a number of lamps? Am i just buying 12v bulbs for that scenario, and because theyre 12v i know they have no driver/transformer/whatever built in, they wont get ridiculously hot, they should last a long time etc....

Anyone know of any good web resources along the lines of "how to buy LED bulbs and wire your home in a way that makes sense for low power consumption, low heat generation and low wallet indentation" because I could just do with a "read this and follow" set of instructions, rather than learning the ins and outs of yet another aspect of building this bloody house.. Or is that the point where someone says "ah. you need a Lighting Engineer!"

You need to run mains to every light position and use direct to mains LED lamps if you want a reliable efficient future proofed installation.

Fanny about with central transformers if you'd prefer over sized conductors, additional material and labour costs, hard to source lamps, increased electricity costs, mega expense in the future ripping it all out etc.

We generally fit dimmerable warm white 6 or 7 watt megaman GU10 230V lamps. They're really reliable, have a good spread of light, good colour and colour rendering and can be dimmed to a low level. We've found V-pro dimmers work well with them.