'dr carl, JJJ' 240v lights + 12v down lights.use same amount of power??????????

the 12v light needs to go through a 240v AC power adapter to turn it into 12V DC... the adapter uses the same power. yes. the difference is you can run heaps more 12V lights off one adapter and the usage doesnt go up as much.

edit* to clarify, one 240V 50W would use the same as one 12V 50W + the adapter, but six 12V 50W wouldnt use any more.

 

I would disagree....the transformers use more power to convert 240v to 12v regadless of the wattage of the globe. Running more globes off one transformer will load it up more and make it use more power because it gets hotter. Heat equals resistance, and the more resistance placed on the transformer, the more power it will draw.

I have just replaced 12v down lights with energy saver 240v ones and our power bill went down quite significantly. Although we were only using one 12v downlight per transformer.

 

Its pretty simple...

The wattage of the bulb represents the amount of energy it draws in a certain timeframe.
50w = 50w.

Incandescent bulbs are relativley efficient electrically but put out a poor light quality, so you tend to use a higher rated bulb for the same net effect. Fluroiscent are better quality light so you can use a lower wattage bulb / tube but at the monor inefficiency of a transfromer - usually about 93-95% efficient. Fluros however are a CHEMICAL reaction rather than an electrical one - you use electricity to excite the inert gas and powder to a higher energy level in the tube. Evebntually the gas sheds a photon and returns to the lower energy level producing light. the powder acts as a 'cascading catalkst' to promote the interaction over a larger volume of gas ant any one time.

Downlights are just microsized versions of this technology.

They are similair in overall efficiency. The big advantage to downlights is that you can FOCUS the lit area far more effectilivey. 50W over 3sqm beats 50w over 20sqm. So you need less, making them cheaper to run.

 

The new LED and OLED options that are starting to emerge are the way of the future I reckon... Saw some pretty cool stuff on Catalyst last night (or maybe the night before - can't remember).

 

The sooner they ban Fluros the better i think. They are crap to try to read with compared to the old type globes and they leave shadows everywhere, plus they are supposed to be bad for the environment because of the phosphorus in them. I use Halogen globes now because they are a much better light than fluros.

 

fluros have their purpose, car show rooms (like mine) will mix normal down lights/globes with fluros, which really helps bring out any pearls or flecks in paint. you can have a crappy swirly black car, park it under globes and fluros and itll look MINT

other than that they are crapola. those halogen star lamps or whatever they are called are the bomb... as long as you have a really high roof or get ready for a tan.

 

v=IxR
voltage equals current times resistance
its all proportional, youll lose a small amount across your transformer
what you really want to look at is Power - watts

fluros use much less power, although if you ran a large amount of them it will stuff up your power factor and power factor correction maybe needed... but i really cant see that applying to most domestic places.

 

dont flouros already come with a cap in them to correct?

 

Its actually P=VI in this case. (power, voltage, current)
You need to leave fluro's on for about 6 hours for them to be more efficient than incandescent bulbs. I've started buying the halogen bulbs, less power, good light and don't start dull and then brighten.

Also, Fluros are pretty bad for the power grid, but thats a bit more technical.

 

how is that possible? they're just a source of resistance, like other electrical components aren't they?

the biggest problem with 12v lights is that the transformer is a potential fire risk in your roof.

 

i put my own batts in. it was before the rebate debacle but at least i know my house isn't going to burn down, or at least not due to dodgy insulation.

 

What you're referring to is the CRI (colour rendition index) of the light source.

Basically, CRI a measure of the lights sources ability to distinguish between different colours, and different shades of colour, when compared to the reference standard, which is the incandescent lightbulb.

For example, the orange street lamps are sodium vapour lamps (they can be either high or low pressure, depending on the application).
Its pretty difficult to distinguish between different colours when viewed under this lamp, hence we would state that this has a low CRI.

On the other hand, when viewing the same colours under a fluor lamp, you can tell the difference between the colours. Hence we would say it has a higher CRI.

 

They are an inductive load which messes with the power factor, without a capacitor they can say use 50VA, but only 30W (made up figures)

The older downlights had the coil wound transformers which did get warm, but all newer downlights just have electronic transformers which have no heat problems, but in both cases its the globe you really have to worry about, it gets very hot. Downlights put in in the last couple of years should have cans on them though