What is a Foot-candle and How Many Does My Facility Need?

To the uninitiated the word ‘foot-candle’ might sound a little odd. So, let’s just get this out there now, what a foot-candle most definitely is not is a new-age spa treatment for the feet. Okay, now we can get to the real meaning of the word! You may have heard the term used in relation to the lighting of a facility and wondered what it is and why it’s important. 

Well, a foot-candle is a measurement of light intensity, defined as the illuminance on a one-square foot surface from a source of light. It is indeed the most widespread lighting measurement in the industry – and is used by lighting professionals to identify and calculate light levels in facilities, buildings and outdoor spaces. A measurement we at Skilled Service use every day on our own lighting projects. 

Foot-candle: a visual explainer

Here’s a simple diagram to show you how a foot-candle is measured:

And if you were to measure it yourself? The process would like this:

1. Stick a one square-foot square to a flat wall.
2. Place a candle one foot – or 0.30 meters – away from the picture on the wall.
3. Observe how one lumen per square-foot will illuminate this entire surface.

Measuring foot-candles

Most lighting specialists will measure foot-candles with a light meter for accuracy.

Once the number of foot-candles have been calculated, they will need to be converted to Lumens.

Converting to Lumens

Here comes the maths part.

One foot-candle = 10.76 Lumens, which means, to convert foot-candles to Lumens, you need to take the amount of foot-candles measured and multiply by 10.76

How many foot-candles are

recommended for your facility?

Ascertaining the correct illumination levels is really important for achieving maximum safety and visual comfort levels in your workplace. Most companies set lighting standards according to the guidelines laid out by the Illuminating Engineering Society of North America (IES) – and if needed adjust those levels to suit their specific operations. How many foot-candles you need for your facility obviously depends on the location you’re in and what your space is used for.

However, the IES has recommended the following foot-candle levels to ensure adequate illumination and safety for occupants:

• Industrial lighting for cold storage/warehouse space/warehouse with aisles: 20 foot-candles
• Open office/private office area/classroom/lab: 40 foot-candles
• Automotive showroom or service area: 50 foot-candles
• Large-item assembly manufacturing: 30 foot- candles
• Medium-component assembly manufacturing: 50 foot-candles
• Intricate, fine assembly manufacturing: 100 foot-candles

Conclusion 

We hope that if you have been in the dark on all matters foot-candles then you are feeling a little more enlightened! If you’d like to speak to one of our lighting specialists today, you can get in touch with us at: https://skservicesllc.com/contact/

And for even more information on the correct lighting standards for safety in your facility, visit the US government’s Occupational Safety and Health Administration department here: https://www.osha.gov/