The first step is to identify the amount of lumens (a measure of light output) for your wash. It’s easy to start with your existing lights as a baseline.

If you are happy with the light output you have, find an LED fixture that is within 10 percent of your current lumen output. Use Table 1 as a reference to see the amount of lumens at different metal halide and LED wattage levels. If you want more light, increase the LED wattage.Table1-PCD0215-LED

Note: Table 1 is based on delivered lumens, not produced lumens. Metal halides produce more light than indicated in Table 1, but most of the light produced is lost and is not delivered to the area being illuminated. Delivered lumens is a measure of light where you want it.

For example: A self-serve carwash has 2 x 400W metal halides per bay. Each 400W metal halide delivers 10,000 lumens, so you have 20,000 total lumens per bay. 

A 1-for-1 metal halide to LED fixture swap would require finding an LED light in the 87W to 100W range (depending on lumens/watt). 

To double the light, find a fixture with higher wattage or increase the number of fixtures. Your target total wattage would be 350W to 400W of LED light per bay.

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