Myth - Low voltage = Low Power


Dedicated elf
Jun 20, 2009
Canberra, ACT, Australia
Low Voltage - does not equal - low power usage

One of the myths of low voltage Halogen lighting.

The truth is it actually means higher energy usage per watt due to conversion losses in transformers and power supply regulators.

The reason we aussies have lower power usage than our american friends is generally the much lower wattage incandescant bulbs used in our strings.
A mini bulb in the US is typically around 240mW to 400mW, this equals the famous 3 series 100ct strings = 1A figure.
A mini bulb in a Aussie 24v string is around 110mW, giving us around 250 bulbs for 1A at 24v

However power consuption is roughly calculated as for 1A

1A at 120v = 120W

1A at 24v = 24W assuming 75% effeciency via a transformer = 32w required from the 240v supply.
32w at 240v = 0.133A

So by the magic of low wattage bulbs we have less current required from the 240v supply.

Last year i ran 15,000 mixed LED and incandescants as well as 240v Rope light from a single 10A power point, dedicated 16A power circuit though.