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What are Light Distribution Types?

Posted by Doug Root on September 14, 2015

There are a lot of important factors to look at when choosing the right light fixture. Lumens per watt, fixture type, warranties, color temperatures are all super important but how about light distribution?

One of the more important things to look at is the lighting distribution of the fixture itself. If you know how to properly figure a layout based on using the right fixture and the correct distribution of light you can lower fixture counts and get a better lit project. You can have a great fixture but if your not putting light where you want it's only as good as the layout!

Light distribution is basically the projected pattern of light a fixture will disperse onto a surface. Lets look at light distribution as it relates to inside the building and outside the building.

  • Indoor beam spread patterns
  • Outdoor light distribution patterns

Indoor fixtures and bulbs typically used beam spreads like 30 degree flood, 270 degree omni-directional & 8 degree spot. The beam spread that you use is the determining factor in how far the light will travel onto a surface. If you have a wide beam of 40 degrees and you want it to pin spot on a sign 20 feet away, you are barking up the wrong tree. However if you use an 8 degree spot that sign will look great!

Outdoor light fixtures use light distribution patterns. The patterns define how light is dispersed from a fixture and is defined by the point at which 50% of the fixture's luminous intensity is met. You will see these distributions used regularly in area lighting, flood lighting & roadway lighting. The industry has identified 5 main types of light distribution patterns. There are others which get into asymmetrical or symmetrical types but we will not discuss those today.

Type I


The Type I distribution is popular for lighting walkways, paths and sidewalks. We use this type of lighting in the middle of the pathway and is great for narrow pathways.

Type II

Type II is commonly used on larger walkways and in roadway lighting as it is good for a larger but still narrow area. You will see this type used on side streets or jogging paths.

Type III

Type III is very commonly used in roadway lighting as it gives a bit more coverage further form the point source outward. Type III lighting needs to be placed to the side of the area, allowing the light to project outward and fill the area. 

Type IV

This light distribution produces a semicircular light that should be used on the sides of buildings and walls. This type does a great job lighting up a parking area perimeter. 

Type V

The widest distribution pattern, excellent for illuminating the inside portions of a parking lot or a 4 way intersection. 

With this basic knowledge it makes selecting the fixture distribution type easy. 

If you are wanting to have a professionally laid out lighting package because this is have come to the right place. We have the capability to layout your parking lot or area using satellite maps and overlaying the fixtures and types to show you where the light will be distributed! Our ALB Energy Solutions team is here to help. Give us a call 770-492-5086, shoot us an email or fill out the contact form here. We offer turnkey lighting solutions, from layout to the installation we are your trusted lighting partner!

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