Down Lights

[Jon]

Can anybody enlighten me on the difference between low voltage downlights and normal ones ( before all the comedians jump in....apart from the voltage ).

I have been told that the low voltage ones are a whiter white. I guess this is because of halogen globes.

We are thinking about down lights in our new rumpus room. What should we choose?

thanks,
Jon

[barnsey]

Jon

As I seem to recollect - 240V downlights generate a fair bit of heat - more so if you've good high wattage spots in them. All this needs a fair amount of ventilation and protection from dust otherwise you pose a fire risk. Seem to remember that a number of fires were started by them.

Equally they are hot if your directly under them so on a hot night you're not doing yourself any favours.

Go low voltage and talk to someone in the know on the spacing - I've loved the ones I've lived with - LV lighting that is!!!!

My 2d worth

Jamie

[ozwinner]

Hi all
A watt is a watt, doesnt matter if its 240v, 12v, or wattever.
It will produce the same energy, light, heat etc.
60 watt 12v, will produce the same energy as 60 watt 240v.
However the current(Amps) though the light will be different; current through the 12V light will be 5 Amps and in the 240V it will be only 1 Amp. Still though with the lower voltage light it will STILL produce the same amount of heat, the heat will be disapated through the transformer.
Cheers, Allan:confused:

[Theva]

Main differences:

LV lights operate at a higher filament temperature than 240V ones; thus more whiter (and efficient) light from 12V units.

Both are halogens.

Of course, there are up market versions of 240V units available which produce same type / colour of light as LV units.

No transformer for 240V units (he he).


Hope this is of some help.


Regards,
Theva

[Honest Gaza]

Jon...just replaced a 240V downlight yesterday with a 12V downlight at the wife's insistance. Before purchasing any downlights, I suggest you take note of the replacement bulb type and then check two things. Availability and cost. We have found over the last couple of years that the 240V replacement bulbs can cost around $7each and are often only available at specilaist "lighting" shops. The 12V downlight that we replaced it with uses bulbs that are around $2.50 and readily available from the local Woolies.

Honest Gaza

[Wood Borer]

The wattage of globes refers to the input power. Globes produce light and heat so the input power is split two ways - light and heat.

Incandescent globes are terribly inefficient in that the majority of power is converted to heat with the minority of power being converted to light. The brightness of a globe depends on it’s efficiency of turning electrical power to light and it’s input wattage.

The colour of the light depends on the temperature of the filament, the material the filament is made from and the coating on the filament. I am talking about clear glass globes.


- Wood Borer

[soundman]

Lets clear a few things up.

Down lights come in a vast range of types using diferent lamp types and forms.

arround the home you will find

older type conventional incandessant types having a standard globe or an R series reflector lamp like a light duty portaflood bulb.
these are usualy arround 6" in diameter.

the above types usualy have a conventional lamp base either screw in or bayonet. these fixtures may also be fitted with a compact fluro lamp.


common & recent times is the dichroic down light which has a small quarts halogen lamp mounted in a glass reflector as the bulb.
these are much more efficient and have a better colour whiter light. the lamps have a two pin fitting that just pushes in.

Untill recently most of these were 12 volt lamps run off a transformer. Of late you will find Dichroic down lights which run directly off 240 volts
The 240 volt types have a fitting similar to a fluro starter that pushes in and turns a little.

my opinion
the older type usualy need a 60watt conventional lamp to be of use at all. and as such are very ineficient and expensive to run.

the best option with these is to replace the lamp with a compact fluressent lamp of about 18 watts. It just plugs in.

The 12 & 240 volt dichroic types are a lot more efficient. the common lamps are 20 watt & 50 watt. The 50 watt unit produces about as much light as a 75 watt conventional reflector lamp.

there is a choice of beam width also.

AS far as the enthusiastic application of down lights is concerned.

They are far toooooo over used. They are one of the most inefficient ways of lighting rooms currently available.
They produce a harsh direct and focused light which is undesirable for general illimination. They almost completely illeminate beneficial reflection from the cieling. AND you require many more of them to light the area in question.

They are excelent for feature lighting such as signs paintings and objects d art.

For general room ilumination circular diffused fluros are a much better option.
or conventional lamps if you want dimming.

It is common to see 10 or 12 of these units used to light a kitchen wher one 40 watt fluro would do a better job.. The silly thing is that they then install a dimmer because the customer cant stand the glare.

Rant ends.

scary thaught
I have a 300 watt par 56 down light knocking round in my shed.

[Theva]

Soundman covered it well; bit more info on domestic versions:


Most of the 12 V down lights are mostly dichroic reflector types, they focus & reflect light downwards but not the heat; also called coolbeams.

Heat builds up around the lamp holder area, so make sure that the ceiling insulation is not covering the lamp.

Light beam (cone) angles varies from 10deg to 60deg; 38deg is the most common. Wattage 20, 35 and 50. Holder type GU5.3

Living room type applications of down lights, up to 4 of 35watt units with a dimmer is sufficient. Typical spacing from the wall is 600 to 800mm.


The 240V versions have metal ( Al) coated reflectors, reflecting light and heat downwards. Beam angles 25 & 50 deg; mostly 50W units. holder type GU10.


To confuse the issue further, there are aluminium coated reflector type lamps for 12V and dichroic type lamps for 240V (with different holder type GZ10).

For living rooms with normal ceiling hight, 12V units are more suitable (if you want down lights); with a dimmer of course.


Hope this is clear as mud.

Regards,
Theva

[Jon]

Thanks all.....

we are thinking about the down lights as we want to put a ceiling fan in the middle of the room and it is hard to get a nice looking fan with a nice looking light attached that you don't have to duck to get under. The oyster style lights are okay in bedrooms but IMHO they aren't real flash in a living area.

Jon

[soundman]

Two further cautions.

be carefull about any lighting located near cieling fans.

If the positioning is such that the light can be viewed thru the sweep of the blade from any angle an unpleasant strobing effect may be experienced.


I will resist the temptation to rant at length about ceiling fans. Hideous & dangerous devices. Unless you have 12 foot cielings or are unfer 4'6" tall in which case they are just hedeous.

[Jon]

Soundman,

my wife and I are both 6ft and are wary about ceiling fans but we have them in all the bedrooms have not injured ourselves yet. We know not to "reach for the sky" while in range.

The strobing effect of the downlights might be a problem though. We will have to look at the room size and light placement, thanks for the tip.

Jon

an aside in relation to low ceilings etc. some friends of our who are vertically challanged installed a low hanging light in their kitchen. Wasn't a problem for them but collected anyone over 5'10" that walked through. ouch.

[stephenmeddings]

We have been renovating and installed downlights in our living areas, kitchen, dining, bathroom and hall ways.

Best idea my wife has had.

Something to think of, if like us, you have a home theater in your rumpus. We have six. The front four are on one switch and the back two are behind our seats and on a dimmer. So most of the time we just use the back two and when watching a movie just dim them down. if I just had another remote......

Except for the kitchen and hall, all the downlights are on dimmers. Makes it easy to set the mood etc

[stephenmeddings]

On the topic of ceiling fans:

This is an x-ray of a young child on his fathers shoulders who forgot about the fan. The arrow points at the fracture.

Apparently this sort of thing is common.

[Ben from Vic.]

Hello all,

While were talking about low voltage downlights, can someone tell me the amount of watts they draw (the 12 volt ones)

I know it converts to about 7 or 8, just wondering if anyone knows for sure.

Ben

[gatiep]

The 12 Volt (any light for that matter) is rated in Watts, i.e. 20 Watt, 24 Watt or 50 Watt.

I think what you want to know is the amps that they draw.

Devide the watts ( ie 24 Watts) by the operating voltage ( ie 12 Volts) .
Thus a 24 Watt 12 Volt light draws 24/12 = 2 amps

Have fun......keep turning

[Ziggy]

Gatiep,

Could you expand your example further for me and tell me the load the lighting circuit will see (at 240 Volts), or is it the same as the light - being 2 Amps. If thats the case our average lighting circuit is 16-20 Amps meaning I could only install 8 to 10 down lights per circuit?

Thanks,

Zig

[Ben from Vic.]

Thanks for your help Gatiep, I have some more difficult questions.

Presuming we are talking about a 12 volt 50 watt downlight, what is the draw on the system in 240 volts (When you convert the power usage from 12 volts to 240 volts)?.

Or, put simply, how many could you plug into a power point before you overload it (not what I plan to do)?.

I'm led to believe that they use less that 10 watts at 240 volts (or about 0.045 of an amp (i think))

Ben :)

[gatiep]

Ziggy & Ben

Unfortunately one cannot do a straight conversion as there is a transformer involved, changing the voltage from 240 Volt to 12 Volts. That is the case with the 12 Volt downlights, there is a factor involved depending on the efficiency of the transformer.

The formula involved for calculating the current ( amps ) drawn is:
Volts x amps = watts or Watts/Volts = Amps

In the case af a 12V x 50 Watt downlight the amps drawn will be
4.167

((( I am looking at a 12 Volt 50 wat downlight with its own transformer and the input is 240 volts ( no amperage given) the output is 11.4 Volts and the current that it delivers is 3.95 Amps. So if we look at the Formula Volts X Amps = Watts ( 11.4 x 3.95= 45.03 Watts. This makes me doubt the "Chinese" Specs of 50W. )))

To keep calculations simple lets stay with the example of the 12 Volt 24 Watt lamp drawing 2 Amps.

If we have a load of 24 Watts and the Voltage is 240 then the amps ( current) drawn will be 24/240 = 0,1 Amps.

This is correct if we have a 100 % efficient transformer. Therefore if we increase the volts 20 times ( from 12 Volt to 240 Volt) then we devide the Amps by the same factor, ie 20 , giving us 2/20 = 0.1 amps

The transformers used are not 100% effective, probably only 75%.

Therefore the amps drawn at 240 Volt side of the 12 volt transformer will be higher and probably in the region of 0.133' Amps.

Sorry for the longwinded post, but I don't know how to put it any other way.

I hope this answers your questions


Have fun................................keep turning

[Ben from Vic.]

Gatiep

No need to appologise, the post was quite helpfull.
Given, as you say, that it all hinges on the efficiency of the transformer, I guess that the only way to find the actual drawer would be to put a muiltimeter onto it, and even then it would likely be different depending on the price you paid for the transformer.

And to answer Ziggy's question assuming a 0.15 amp drawer, a 20 amp circut could power up to 130 low voltage downlights

Ben :D

[Ziggy]

Thanks guys, does clarify things a little :)