GU10 vs Low Voltage?

[grommett]

Can anyone tell me the advantage of using low voltage lighting over 240v GU10 dichroic halogen lamps? It seems to me that GU10's would be better as they do not need transformers and can always be changed for LED's when the price comes down.

Thanks

Grommett

 

[dwcshoot]

Hi.

You will find the light output from a low voltage lamp is a lot better than from the GU10s.

 

[ban-all-sheds]

1) 240V is low voltage: //www.diynot.com/wiki/electrics:voltage-bands

2) Neither are any good for lighting up room spaces. Small 2" reflector lamps came out of the retail display market, and they were designed to highlight or illuminate small areas or individual items. They are often called spotlights, for the simple reason that that's what they do - they produce spots of light. They are actually specifically designed to not provide evenly spread room illumination.

 

[ericmark]

The extra low voltage inverter that drives the extra low voltage lamp also corrects the voltage and because the control is better the brightness can be slightly increased (Colour temperature) and combined with this the element is also thicker so lasts longer.

However of course there is more to go wrong. Not uncommon for a lamp to take the inverter out with it when it blows. There is often both a min and max voltage. The dichromic and non dichromic lamps both fit into the same holders so easy to overheat the fitting. There is a larger range of angles again easy to replace with wrong one. Also will not take discharge lamps like the cold cathode. Even the LED lamps will not always work due to min ratting of inverter (loosely called a transformer).

No tungsten halogen lamp should be dimmed as the lamp life will be reduced as it will run too cool but many do want the ability to dim and much harder with extra low voltage lamps.

So although there may be places where the extra low voltage are better of course where SELV is stipulated like certain areas of a bathroom in general the GU10 and GZ10 lamps offer more benefits than the extra low voltage equivalent. GU is standard and GZ is dichromic and GU lamps will fit in GZ holders but not the other way around. Although theory says they don't last as long that really depends on local conditions and I notice no difference where I live. And GU10 is so much cheaper to start with one would need to change loads of lamps before the extra low voltage version caught up. And as stated inverters do blow and replace one or two of those and you will never catch up in running costs.

So in general GU10 is better option. However these are spot lamps and are designed to light a very small area for example a picture on the wall and with a picture on the wall the colour temperature is very important so where correctly used the extra low voltage version is better in many cases. Only where incorrectly used for general lighting will the GU10 version shine. But in general the little spot lights are incorrectly used.

 

[ericmark]

Hi.

You will find the light output from a low voltage lamp is a lot better than from the GU10s.

Nonsense a GU10 is a low voltage lamp so how can a low voltage lamp be better than a low voltage lamp?
Low voltage is 50 to 1000 in an AC circuit.

 

[dwcshoot]

Hi.

You will find the light output from a low voltage lamp is a lot better than from the GU10s.

Nonsense a GU10 is a low voltage lamp so how can a low voltage lamp be better than a low voltage lamp?
Low voltage is 50 to 1000 in an AC circuit.

Ok technically you are correct.
In terms of the question I assumed it was between 230v GU10 and 12v MR16 type lamps.
When I said LV I meant the 12v compared to 230v

 

[mbga9pgf]

1) 240V is low voltage: //www.diynot.com/wiki/electrics:voltage-bands

2) Neither are any good for lighting up room spaces. Small 2" reflector lamps came out of the retail display market, and they were designed to highlight or illuminate small areas or individual items. They are often called spotlights, for the simple reason that that's what they do - they produce spots of light. They are actually specifically designed to not provide evenly spread room illumination.

you will want these;

http://www.lyco.co.uk/Light-Bulbs/Halogen-Bulbs/Low-Voltage-Spotlights/sc1369/p3488.aspx

60 degree wide angle Flood. Light quality is far better than those nonsense CFLs that take ages to warm up. Bounce them off lightly coloured walls and you get very good illumination. Use this FREE software (difficult to learn but the raytrace is VERY accurate) - Relux suite.

One thing I would note; they throw out a lot of heat so make sure you are aware of the regs wrt spacing. Have a good think of where your floor joists are in the ceiling so you can actually do what you plan in terms of spot pattern; we made small test holes using a 1mm drill bit to ensure we had the required spacing on the joints.

Other thing, make sure that if you use ELV rather than LV that the transformers are accessible (IE not laid under laminate etc) as the can and do fail... Ripping up fitted carpets and tongue and groove chipboard flooring for a single failed tranny would get the wife wincing. For me, it had to be ELV.... once failure rates of lamps had been considered. Its more expensive (DONT hook up lights using long runs of cable, simply buy a transformer for each downlight) but once its in, they look uber.

I looked into PL lighting but the cavity sizes required to fit the bulbs in were completely unworkable and they looked a joke and they didnt adequately illuminate our living room which is 8 metres by 4 metres... Only 550 watts of downlight and white walls gets the lighting to an illumination level that is suitable.

I do highly reccommend using software such as relux and doing your research - if you do what the last bunch of idiots did and not think about the quality of light and also the intensity distribution, downlights can look completely naff. Spend 5 hours getting to grips with relux and you can make up your own mind over what is the best lighting solution for your living space.

 

[flameport]

I looked into PL lighting but the cavity sizes required to fit the bulbs in were completely unworkable

Not true - http://www.tlc-direct.co.uk/Products/GLPL226E.html are among the largest size PL type lights, yet only require a depth of 145mm, less than any recessed halogen spotlight.
Diameter 200mm, which is still far less than the spacing between joists, and in the unlikely situation of a ceiling with joists less than 200mm apart, halogen lights couldn't be fitted anyway, as there wouldn't be enough horizontal clearance to allow the vast amounts of heat to dissipate.

 

[mbga9pgf]

I looked into PL lighting but the cavity sizes required to fit the bulbs in were completely unworkable

Not true - http://www.tlc-direct.co.uk/Products/GLPL226E.html are among the largest size PL type lights, yet only require a depth of 145mm, less than any recessed halogen spotlight.
Diameter 200mm, which is still far less than the spacing between joists, and in the unlikely situation of a ceiling with joists less than 200mm apart, halogen lights couldn't be fitted anyway, as there wouldn't be enough horizontal clearance to allow the vast amounts of heat to dissipate.

20cm diameter?

Its a living room, not a top shop display stand. And at a whopping 27 quid each, not including bulbs, they aint exactly cheap. I very much doubt they would have a 60 degree flood on them, although I could be wrong on this.

as there wouldn't be enough horizontal clearance to allow the vast amounts of heat to dissipate

Depends if you insulate the sides where regs dont allow spacing. Having installed these, the regs are completely over the top; feeling joists within 10 cm of the lamps and the joists are only getting warm.

And I dont kinow where you are getting your downlights from, but mine are nowhere near half a foot deep (145mm)

 

[mbga9pgf]

Deleted

 

[Steve]

I have 2 of those PL downlights in my kitchen. The reason they use them in retail to iluminate sales areas is that they DO have a VERY wide beam on them. About 150 degrees (a straight line being 180 deg). I wouldnt use them in a living room, but for a kitchen, the next best thing to fluorescent strips.

 

[flameport]

at a whopping 27 quid each, not including bulbs, they aint exactly cheap.

You wouldn't need 11 of them for that room, 2 would be more likely, and they would use far less energy than the halogen downlighters you have.

I very much doubt they would have a 60 degree flood on them, although I could be wrong on this.

The angle is far more than 60 degrees.

And I dont kinow where you are getting your downlights from, but mine are nowhere near half a foot deep (145mm)

The fittings might not be, but they require at least that much space above them to avoid heat damage to whatever is above.
If your existing lights are only 10cm away from a joist they are probably too close, but in any event that already allows for a 200mm diameter hole.

 

[mbga9pgf]

You wouldn't need 11 of them for that room, 2 would be more likely, and they would use far less energy than the halogen downlighters you have.

Not a chance. We ran PELs in relux and the room was dark and dingy. didnt even hit 50Cd on the foor. We have beams which extend about 9 inches below the ceiling creating some pretty big shadows. This was why we had to go with lots of spots.

That was my original point; unless you plug your intended layout in a raytrace suite such as Relux, you wont have the slightest clue what its going to look like unfortunately... We ran it with lamps +PELs, Halogen + Lamps, Pendants, nothing worked, unless we went to matt white walls and wide angle floods.

Give you an idea, this is it painted, pre-cleanup.

Untitled

• mbga9pgf
• 5 Jan 2011
• 1

We are going round and retrospectively removing the downlights they have put into the bedrooms, completely pointless in a lot of respects and we will bereplacing with simple pendants.[/img]

 

[mbga9pgf]

I have 2 of those PL downlights in my kitchen. The reason they use them in retail to iluminate sales areas is that they DO have a VERY wide beam on them. About 150 degrees (a straight line being 180 deg). I wouldnt use them in a living room, but for a kitchen, the next best thing to fluorescent strips.

If we can fit them in the kitchen, I might look at using them rather than Halogen. Much is about compromise however, I wouldnt mind betting a couple of halogen spots would make all the difference.

 

[ban-all-sheds]

20cm diameter?

Its a living room, not a top shop display stand.

How many examples of lights designed to be used in living rooms which are 20cm or more across would I need to find for you to realise that there is nothing intrinsically wrong with that size?