Please help with dimmable lighting - argh!

[MasterMark]

I'm going a little crazy here, so hopefully can put me straight. Planning a house refurb, and just picking the downlights we want. Dimmable is very important for me, but my understanding was that it is the bulb, not the fitting, that determines whether a light is dimmable or not.

But looking at the tech specs of the fixtures below, the first says not dimmable, the second says it is. Other specs are very similar, both 240v, GU10, the first 11W, the 2nd 10W and insulation covered. It wouldn't bother me at all if the second one wasn't considerably more expensive, as in all other aspects the lights are close enough to identical for my tastes (slight size differences).

As an extra question, the 1st one is specified as Part L1 compliant. The 2nd isn't, but safe to assume it is?

Any help would be much appreciated?! Thanks!

http://www.aurora.eu.com/ProductPages/LampDatasheet.aspx?g=6223

http://www.aurora.eu.com/ProductPages/LampDatasheet.aspx?g=7119

 

[ban-all-sheds]

I'm going a little crazy here, so hopefully can put me straight. Planning a house refurb, and just picking the downlights we want.

Small diameter downlights are no good for general room illumination. If you want recessed lighting you should use large diameter ones.

Dimmable is very important for me,

Then be very careful about using low-energy lamps with integral ballasts.

Do not buy anything without seeing it working first. You may find that you are very limited in your choice of dimmer switch, you may find that you have to keep buying the same lamps for ever, and not change to another make, you may find they won't dim enough, you may find (despite what they say) that they flicker, you may find that the dimmers make a noise, you may find that the lamps change colour....

If you want to dim fluorescent lights you really should be considering the sort which do not use lamps with integral ballasts but use external ones which are, or can be converted to 0-10V or 1-10V dimming control.

but my understanding was that it is the bulb, not the fitting, that determines whether a light is dimmable or not.

Not if it has external control gear, or not if it only takes a lamp type which can't be dimmed.

But looking at the tech specs of the fixtures below, the first says not dimmable, the second says it is. Other specs are very similar, both 240v, GU10, the first 11W, the 2nd 10W and insulation covered. It wouldn't bother me at all if the second one wasn't considerably more expensive, as in all other aspects the lights are close enough to identical for my tastes (slight size differences).

You mention price.

Have you looked at the price of lamps for the first one?

They'll have integral ballasts which is why they aren't dimmable. Makers have tried (with varying degrees of success - see above) to make dimmable MR16 CFL lamps for the halogen replacement market - I guess there isn't the demand for PAR20s.

But PAR20s are also very likely to be too small to light up rooms properly. Basically you'd be trying to evenly illuminate your rooms with torches embedded into the ceiling.

You should spend time looking at proper lighting shops and websites - cast your net wider than the limited range of cr*p they have in the sheds. As the old saying goes, if all you have is a hammer, everything looks like a nail. And if all you do is look in DIY sheds or web retailers competing purely on price everything that isn't hideous looks like a downlighter.

As an extra question, the 1st one is specified as Part L1 compliant. The 2nd isn't, but safe to assume it is?

No.

It might be, but never assume.

 

[ericmark]

1) Quartz lamps should not be dimmed although often are.
2) LED lamps often use some control gear and as a result normally can't be dimmed.
3) Cold Cathode or Florescent need very special control gear to dim in the main where control gear is part of the lamp they are not dimable.
So really GU10 lamps are not normally able to be dimmed. There may be exceptions where they are specially designed to dim but in the main they will not dim.

The norm abroad where florescent lamps have been used for many years as they don't want to heat their house is to use a 1/3 and 2/3 split in switching lights giving 3 light levels.

Although florescent lamps can be dimmed go into any lecture hall the control gear required is rather expensive and for home use you need to look at tungsten lamps to do it to budget.

There are specials see here but you have to pay well over normal price.

 

[ban-all-sheds]

Yo - clarification of my earlier post.

To keep control cost down you want ballasts which do 1-10V dimming, not 0-10V. They are completely different systems - with the former the ballast provides its own control voltage which goes to the 1-10V dimmer (MK make one - I'm sure there will be others).

With the latter you need to provide power to the dimmer and it sends the 0-10V control voltage to the ballast (or it talks to a dimmer pack using a protocol such as DMX or DALI which provides the control voltage).

The latter is overkill if all you want is a knob to twiddle, but might be of interest if you want to get into automation.

See //www.diynot.com/forums/viewtopic.php?t=236100&start=0

 

[RF Lighting]

But PAR20s are also very likely to be too small to light up rooms properly. Basically you'd be trying to evenly illuminate your rooms with torches embedded into the ceiling.

This maglite theory of yours, what happens when you twist the end of a maglite?

 

[ericmark]

I have 2 GU10 lamps behind my bed head around 1.5 meters from any book I want to read and they do a great job lighting the book without lighting the whole room.

They do as designed and give a spot light where required.

If however you don't want a spot light then the GU10 is not the answer.

In a large room as general lighting the GU10 makes the room look like a planetarium and one is reminded of chocolate fire guards.

I tried the LED and cold cathode versions of the GU10 and as spot lights they were hopeless lighting areas not requiring light (my wife's side of the bed) and not giving enough light where required (my side of the bed).

The Kindle has reduced the problem in getting only the area required lit. But at rather a high price. When she uses the auto read function light is not a problem however noise is.

It is a case of selecting the right lamp for the job. The GU10 is a great spot light. But not any good for general lighting.

In my bedroom heat is not a problem. Need a little extra heat when reading in bed. But in the kitchen heat is a real problem and the less heat the light produces the better. I spent out a lot of money for an induction hob which keeps kitchen cooler no point in then fitting GU10 lamps to heat it up again.

Remember lamps only "Save energy" if you don't want the non light energy. If using so called "Energy saving lamps" means the thermostatic radiator valve turns the radiator on for longer then it has not saved energy. It may have saved money as gas is cheaper than electric but has not saved energy.

 

[ban-all-sheds]

This maglite theory of yours, what happens when you twist the end of a maglite?

The beam becomes halo shaped.

 

[MasterMark]

Thank you to all, lots of very very useful info for me to look through.

The reason our architect has suggested recessed spotlights (which we have now) is that the ceilings aren't particularly high, so anything that "hangs" from the ceiling isn't going to work. Not enough space for wall lights, although I wouldn't chose them anyway for general lighting.

So, given we have to satisfy building control, L1 compliance etc, not sure what other options I have? For example, at the mo I have a 5.5m*5.5m room with 10, cheap and cheerful 50w halogen spots. The amount (and type) of light is perfectly acceptable to me (certainly used to it), so I'd be happy with an "equivalent" to this. 500W for one room is a lot of wattage (and running costs!), but I guess I have to do "low energy" these days anyway.

I've found dimmable LEDs (auraglow, Philips, or CREE), but didn't realise the GU10 ran so hot.

Happy to broaden my search, but if anyone has any suggestions about what kind of spots/bulbs I should be considering for spot-lighting, that would be very helpful. In terms of price, the fittings I was looking at retailed at £10-£20 (depending on fire-rated, IP65 etc), with the bulbs retailing at £10-£15. Assume my builder will get trade discounts, but bearing in mind I may have 40 or so spotlights, this is going to add up!

 

[SimonH2]

I'm generally in agreement with BAS - spotlights are designed to light up what is in front of them, in a spot. A friend decided he likes them though, and he's just had his bathroom ceiling done - cladding and recessed spots. He used four Halers fittings (may be these, if not then similar) in a square pattern in a 2.2 x 2.1m bathroom. I was actually surprised that they aren't half as bad as I expected - and they do dim quite nicely with the brass dimmer he's got.

The fact that the installer ignored the manufacturers instructions because he believes "fire rated" means "doesn't need air space" is another mater - I can fix that, but at least he has his paperwork to make it legal even if it's not safe