Lighting is only done properly when you get the light where you need it. Too wide of a pattern and its dark and inefficient. Too narrow and it can be harsh with too much hot spots and shadows.

In order to help design lights correctly, industry organizations such as IES and NEMA have established various classifications to help categorize lights.  IES light classifications are I-V and are typically focused on parking lot and street lighting.   They are notable in that 3 of those road patterns have different side to side beam angles than forward.  NEMA can mix angles, but not as common.

The NEMA classifications below are the same, essentially making a circle (unless a luminarire is designed for other) in the beam angle.

What are NEMA Light Classifications?

A: NEMA light classification takes the beam angle of a light and groups it into one of 7 categories from very narrow spotlight to very wide flood pattern.  This helps define light types and their ideal usage.

NEMA BEAM CLASSIFICATIONS

Beam Angle NEMA Classification Name

From 10° - 18° I (aka one or 1) Very Narrow

From 18° to 29° II (aka two or 2) Narrow

From 29° to 46° III (aka three or 3) Medium-Narrow

From 46° to 70° IV (aka four or 4) Medium

From 70° to 100° V (aka five of 5) Medium -wide

From 100° to 130° VI  (aka six or 6) Wide

From 130°+ VII (aka seven or 7) Very Wide

These NEMA classifications are often shortened to look something like 5H5V.   This equates to 5 horizontal and 5 vertical from the pattern above. Many lights, such as sports, stadium and high mast are just listed as NEMA 3, indicating a round pattern.

The official rule to calculate beam is where the light is 10% or higher as a percentage of the maximum;  So if its 30 degree beam angle but 9% is wider than that, its still a 30 degree beam.   The bleed out is within spec.  This rule is also true in H + V patterns, where each direction has to meet this number.

Many manufacturers provide photometric reports on their product data sheets, giving you enough information to determine whether or not the fixture will meet the requirements of the intended application.

At LONG SUN LED, we specialize in LED solutions for indoor and outdoor applications. If you are looking for a fixture, need a lighting layout, or want a quote for a project, our certified lighting experts happy to help. Please feel free to contact us.