[url=http://www.ile.org.uk/documents/frequently_asked_questions.htm]Someone here [/url] said:
6. What is the cost of operating a streetlight?
The lamps used in streetlights vary in both size and consumption (typically between 35 and 250 Watts) depending upon whether they are lighting a residential area, main road or a town centre. Therefore, there can be no one answer to this question. The average cost of operating a streetlight inclusive of energy costs, lamp replacement and maintenance is calculated as between £30 and £50 per annum, less than £1 per week. The forthcoming Best Value Indicator required by Government should give a better indication of the cost in future years. See also answer to Question 7.
7. How much energy does a streetlight use?
The energy consumption of a streetlight is affected primarily by the wattage of the lamp, see Question 6 and by the location of the streetlight in the country, which determines the number of hours of operation each night. It is generally assumed that the average wattage of a streetlight is about 80 watts. Assuming an average number of hours that the streetlight is on per annum as 4,100 then the amount of energy consumed by an average streetlight over one year will be 328 units of electricity, approximately 4.5 pence per night or £16 per annum. See also answer to 6.
8. How many streetlights are there in the Country?
The Institution of Lighting Engineers in its leaflet 'Protecting a Vital Asset' determined that there were approximately 6.2 million lighting columns in public ownership.