Recommended Foot Candle Chart

What is a Foot Candle?

A great place to start is with the definition. For those of you who may not be familiar with them, a foot-candle is a measurement of light intensity. One foot-candle is defined as enough light to saturate a one-foot square with one lumen of light.

If that sounds vaguely like the definition of a lumen, you aren’t wrong. Both lumens and foot-candles are measurements of light intensity.

While lumens measures the amount of light created by a lighting fixture, foot-candles is a measurement of the amount of light that reaches a surface area.

In accordance with other factors, foot candles allow electricians and facility managers to carefully and thoughtfully develop an effective lighting plan.

After all, it doesn’t matter how much light a  bulb emits if none of that light reaches the desired surface area.

Why Are Foot-Candles Important?

Foot candles are an extremely important part of designing an effective lighting setup. They are the only way to tell if an area is actually receiving the intended light levels.

And, although this is important in any type of business, it’s especially important for commercial and industrial facilities to have appropriate lighting levels for both employee safety and efficiency.

It’s so important, in fact, that OSHA has specific foot candle requirements for certain spaces and industries.

OSHA Requirements

OSHA, or Occupational Safety and Health Administration , was created to protect workers by ensuring that working conditions were safe and as risk-free as possible.

As a part of their safety initiative, OSHA developed standards to make sure that all commercial and industrial workplaces have lighting that is adequate and effective, without having a glare or being excessively bright.

Glare and excessive lighting, which can cause headaches and eyestrain to individuals’ overtime. Read more about OSHA guidelines from the United States Department of Labor.

First aid locations, general office spaces, and hospital infirmaries: 30 foot candles
Factories: 10 foot-candles
Construction sites: 5 foot-candles
Warehouse spaces, covered walkways, interior corridors, exit locations: 5 foot candles
General under ground areas of work – mining and tunnels: 5 foot candles
Areas of Concrete placement, waste location areas, loading docks, storage areas, field maintenance locations, refueling locations and excavation sites: 3 foot candles

Understanding Lighting Plans

A Photometric Study, or Lighting Plan,  is a report detailing the light levels and light distribution for a location, either indoors or outdoors. It’s done by software that’s was specifically created to do so.

Lighting Plans allow you to simulate a space, add lighting fixtures, and set mounting heights and fixture locations within the software model.

The software calculates light levels and how balanced the light is and produces a report showing average, max, and min foot candles.

For this discussion, the numbers we discuss are the average recommended foot candles. Just as important are the max/min ratio the study calculates. The higher this number is, the more spotty the lighting.

So it’s one thing to hit the recommended average. It’s another to design a lighting solution with even light distribution. A lighting plan study will provide you with this information.

Understanding Light Efficiency

Even amongst LEDs, not all bulbs are created equal. Though they are all more efficient than options like fluorescents and metal halide options, not every LED is equally efficient.

This is another reason why it’s important to pay attention to the lumens of an LED light instead of the watts. In many cases, a higher quality LED with lower wattage can produce a brighter light than one with a higher wattage.

Let’s explain this showing 2 examples.

One fixture is a light at 130 lumens per watt. The other is a light at 180 lumens per watt.

To produce 20,000 lumens, the first light needs 153.84 watts. The second light only needs 111.11 watts. That’s a difference of 42.73 watts. This is what saves you money on your lighting bill.

Both lighting products above create the same amount of light, or lumens.

Efficacy, or light efficiency, is another important thing to factor into a light purchase. A more efficient light may cost more at the time of purchase, but over the life of the product, your utility bill will be lower.

And the amount you save with a lower utility bill will far exceed any additional purchase cost. If you want to learn more about LED lumens and all that goes into them, we’ve summed it up nicely in this post.