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Ask G: 'High intensity' halogen lights

What's the deal with 'high intensity' halogen globes?

I was about to replace my 50 watt halogen globes with 35 W 'hi intensity' halogens. However, my local lighting shop told me that using a lower wattage bulb makes no difference to power consumption because the transformer will always draw 50 W+ irrespective of the globe. Another shop told me that it will save me power. Who do I believe?

Peter, QLD

Halogen globe

Credit: Wikimedia

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It sounds like 'voltage' and 'wattage' might have been confused. Contrary to popular myth, low-voltage downlights are NOT low-energy downlights. The wattage is the indication of how much electricity will be needed.

Halogen bulbs advertised as 'high intensity' are either those with an infrared coating that enables them to use less power to give a similar light output, or those with a broader angle which disperses the light over a larger space.

Again, it's the wattage that counts, so a 35 W bulb uses less power than a 50 W bulb.

The transformer, which converts a 240-volt current to 12 volts, draws power itself, irrespective of the wattage of the bulb plugged into it. The bottom line is that the 35W bulbs, though generally more expensive, will use less electricity.