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# Long description

This is a line chart showing the performance of different lamp types of different power ratings. Generally for any given lamp type the efficacy increases with power rating and light output. The x-axis is labelled ‘initial lamp lumens’. It has a logarithmic scale running from 100 lumens at the left to 100 thousand lumens at the right. The y-axis is labelled ‘luminous efficacy in lumens per watt’ and has a scale running from zero to 200. A black line representing the performance of conventional incandescent general lighting service or ‘G’’L’’S’ lamps appears at the bottom of the chart. At the left hand end is a lamp with a 15 watt power rating. This has a light output of about 120 lumens and an efficacy of about 8 lumens per watt. At the right hand end of the line is a lamp rated at 1000 watts. This has a light output of 2000 lumens and an efficacy of 20 lumens per watt. Above this is another black line labelled ‘tungsten halogen’. At the left hand end is a lamp rated at 100 watts. This has a light output of about 1500 lumens and an efficacy of about 15 lumens per watt. At the right hand end is a lamp rated at 2000 watts with a light output of 4000 lumens and an efficacy of 20 lumens per watt. Above this to the left is another black line labelled ‘’C’’F’’L’ or compact fluorescent’. At the left hand end of this is a lamp rated at 5 watts. This has a light output of about 220 lumens and an efficacy of about 43 lumens per watt. At the right hand end of the line is a lamp rated at 23 watts. This has a light output of 1400 lumens and an efficacy of 60 lumens per watt. To the left of this line is a white area in the chart labelled ‘white light emitting diodes’. Two arrows show the progressive development from about 100 lumens output at an efficacy of 40 lumens per watt towards 500 lumens output at an efficacy of 80 lumens per watt. In the centre right of the diagram is a green line labelled ‘’M’’B’’F’ or high pressure mercury discharge lamps’. At the left hand end is a lamp rated at 50 watts with a light output of 2000 lumens and an efficacy of 40 lumens per watt. At the right hand end is a lamp rated at 1000 watts with a light output of 6000 lumens and an efficacy of 60 lumens per watt. In the centre of the diagram is a black line labelled ‘fluorescent (tri-phosphor)’. At the left hand end of this line is a lamp rated at 18 watts with a light output of 1400 lumens and an efficacy of 80 lumens per watt. At the right hand end of the line is a lamp rated at 100 watts with a light output of 95000 lumens and an efficacy of 95 lumens per watt. To the right of this line is another one coloured orange labelled ‘’S’’O’’N’ or high pressure sodium discharge lamps’. At the left hand end of the line is a lamp rated at 50 watts with a light output of 3800 lumens and an efficacy of 75 lumens per watt. At the right hand end of the line is a lamp rated at 1000 watts with an output of 120 thousand lumens and an efficacy of 120 lumens per watt. Beneath this line at the right of the diagram is a green one labelled ‘’M’’B’’I’’F’ or metal halide high pressure mercury lamps’. At the left hand end of this line is a lamp rated at 250 watts with a light output of 20 thousand lumens and an efficacy of 80 lumens per watt. At the right hand end of the line is a lamp rated at 1000 watts with a light output of 9500 lumens and an efficacy of 95 lumens per watt. At the top right of the diagram is an orange line labelled ‘‘S’’O’’X’ or low pressure sodium discharge lamp’. At the left hand end of this line is a lamp rated at 35 watts with a light output of 4500 lumens and an efficacy of 130 lumens per watt. At the right hand end of the line is a lamp rated at 180 watts with an output of 35000 lumens and an efficacy of 190 lumens per watt. Above this line and to the left is another orange line labelled ‘’S’’O’’X’’E’ or higher efficacy low pressure sodium discharge lamp’. At the left hand end of this line is a lamp rated at 18 watts with a light output of 1800 lumens and an efficacy of 100 lumens per watt. At the right hand end of the line is a lamp rated at 131 watts with a light output of 26000 lumens and an efficacy of 200 lumens per watt.