Electricity If you have an electrical appliance that uses x watts of electricity, and use it 24/7, the cost of running it is about x dollars per year. Note that most appliances, such as computers and fridges only give the maximum power usage, the actual power usage may be much less, or it may only draw power some of the time. Example: A computer that uses 200 watts, running 24/7, costs $200 per year in electricity. Example: A 60 watt light bulb, running 4 hours per day (1/6 of the time), costs $60/6=$10 per year. Example: Replacing a 60 watt light bulb with a 10 watt compact fluorescent light bulb (running 4 hours per day) will save $(60-10)/6=$8 per year. Depending on your house, your circuits may be 10amp,15amp or 20amp (you can check at your fusebox). To convert to wattage, remember V=IR and so multiply by 240. The maximum for a standard appliance or powerboard is 2400 watts. You can figure out which power points are on a particular circuit by switching the circuits on one at a time at the fusebox. Example: A 5 amp heater uses 1200watts. Example: A 2400 watt heater uses 10 amps. Example: A computer with a 400-watt power supply, 2 20watt desk lamps, an aquarium with 120 watts of lighting and a 35 watt pump and a 200 watt heater, a laptop of about 200 watts and a mobile phone charger can work off a single power point as they draw much less than 2400 watts. If you have a 20amp circuit then you could also run a 2400 watt heater from another power point on the same circuit. Water and rainfall. A hand-held hose uses 1000 litres per hour. x mm of rain over y square metres produces x times y litres of water. What x mm of rain in an area means is that the area will be covered with a layer of x mm of water if there is no runoff. 10 mm of rain is a very decent watering of your plants. Example:This is the equivalent (for a 10x10 metre area packed with plants, or a 50x2 metre bed) of 1000 litres of water, which is 1 hour of hand watering! Home rainwater tanks vary from 350 litres to 10,000 litres (we recommend 10,000 litres!) 1 litre of water weighs 1kg, and is the equivalent of a cube of water of length 10 cm... which is equivalent to 1mm over a square metre. Internet At 56 kbps, you can transfer 20 MB per hour,i.e. 500 MB per day. Comments by visitors: Email webmaster@iliveinsydney.com if you need to contact the webmaster.