To calculate how much it will cost to run a street light, you need to know the number and power of the lights and the electricity cost in your area. Then you can multiply these values to get the answer. Suppose there is a one-kilometer ordinary street where people set fifty 60-W street lights. If the electricity cost is $0.2 kW/h, then the total costs per hour will be 50*60*0.2/1000 = $0.6.
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