Do you know what foot-candles are? Know the basics of lighting before you buy

Do you know what foot-candles are? Know the basics of lighting before you buy

Are you looking to purchase or upgrade your lighting? Before you do, make sure you are familiar with the basic parameters so you don’t become confused and end up with the wrong lighting solution. These basic parameters apply to both traditional and modern LED lighting solutions.

With the introduction of the LED light fixture, the biggest difference in the market has been increased flexibility in the options that impact performance. Let’s go through the key elements that define a light source and what you should look for when purchasing lighting solutions so you can have a basic understanding before your search begins.

Wattage (W)

Wattage is a unit of power. More wattage means more power consumed which results in a higher energy bill.

The single worst way to decide what kind of luminaire to buy for a modern buyer is wattage. In the past, wattage scaled against output for most sources. With LED lights, the wattage is a great comparison tool for how well the product converts electrical energy into light – but that is it.

When looking at buying a light fixture, it is recommended that you wait until you are at the point of product comparison before looking at the wattage. Once you have balanced the other factors, buying a light with the lowest wattage that meets your requirements is ideal because this will lower your electrical bill the most.

Lumens (lm)

Lumens are a unit of luminous flux. More lumens mean a brighter luminaire.

Note that lumens “know no direction” – this is the amount of light emitted, but it could be in any direction. The traditional A19 “globe” bulb is a good example of a light that emits light in almost every direction, certainly from 0 to 180 degrees. A flood lamp generally has an inclusive reflector that directs those lumens in a specific pattern.


Foot-candles (fc)

Foot-candles are a unit of light density.

foot candle - diagram

This is measured on the working surface. This is more important that lumens since it indicates how much light is actually getting to where you want it. The reason why light fixtures don’t have this value displayed is because it is highly dependent on the installation, such as reflectance and neighboring light fixtures.

Correlated Color Temperature (CCT)

Correlated Color Temperature is a way to measure the color of white light. Lower numbers have more of a red or “warm” hue and higher numbers have more of a blue or “cool” hue.

Generally speaking, office environments favor 4000K and manufacturing areas 5000K. For residential applications, 3000K and 3500K are more common.

Color Rendering Index (CRI)


Color Rendering Index is a measurement of the ability of a light to make objects illuminated by it appear in their correct color.

Unfortunately, this is a tough metric to get right because LEDs can produce a wide range of spectrums that result in the same CRI and CCT.

Now, as you begin your search for the best lighting solution, you have a basic understanding that will help guide you. Keep these lighting terms and information close as you narrow down your options. Don’t just pick one and go; make an educated decision that will have the biggest – and best – impact for your application and your bottom line.