Understanding Light Bulbs | Frye Electric

Bright light bulb on blue backdrop.

The lamp next to your bedside table has stopped working. The light bulb is dead. You head to the local grocery store to purchase a new bulb, but there is an entire aisle with an endless amount of different choices. Understanding how light bulbs work and the difference between the components can ensure you are choosing the right light for what you need.

Types of Light Bulbs

Incandescent bulbs are the original bulb. An incandescent bulb typically consists of a glass enclosure containing a tungsten filament. An electric current passes through the filament, heating it to a temperature that produces light.

Incandescent bulbs have slowly been phased out as more efficient bulbs have been introduced into the market.

LED Bulbs

LED stands for light-emitting diodes. With LED lights an electrical current passes through a microchip, which illuminates the tiny light sources we call LEDs and the result is visible light. LED light bulbs are traditionally the most energy-efficient option.

Fluorescent light

When you think of fluorescent lighting, you often think of an office or classroom. Fluorescents are long tubular bulbs filled with mercury vapor. When electricity is turned on, the mercury vapor emits light.

CFL Bulbs

Using the same technology as fluorescent lights, compact fluorescent lights (CFL) are made up of a much smaller tube that is spiraled.

Watts, Lumens, Kelvin

Understanding the difference between the type of light bulbs is only the starting point. Every light bulb has wattage and luminance that will determine how much light it emits and how much electricity it uses.


Wattage is the amount of energy a light bulb uses. The lower the light bulb wattage, the lower the electric bill.


Luminance is the amount of light emitted from a light bulb. More lumens equals brighter light; fewer lumens equals dimmer light.

It is not always obvious what the ideal luminance is for the space you are trying to light. There is a system of determining how many lumens are needed to effectively light a space. The measurement is a foot-candle. A foot-candle is how bright a light is one foot away from its source.

A dining room, for example, will generally require 10-20 lumens per square foot whereas a bathroom or kitchen typically is best lit with 70-80 lumens per square foot.

Kelvin Temperature Scale

Another important aspect of light bulbs is their temperature. Different light bulbs will emit different colors of light. The color of the light is measured by the Kelvin temperature scale.

A light that is lower on the Kelvin scale will emit warmer light, whereas higher temperatures will result in cooler lighting.

Light Bulb Labels

With so many aspects of an individual light bulb, labels are printed on bulb boxes to help consumers understand what they are getting.


Brightness is the luminance of the light bulb. This light bulb is 800 lumens. 800 lumens would be a good amount of light for an average size dining room or smaller bedroom, but may not be the best choice for a kitchen or bathroom.

The best way to determine the specific amount of lumens necessary for your space is to use the foot-candle measurement.

Estimated Yearly Energy Cost

The estimated yearly energy cost is very much just an estimate. Without knowing the cost of electricity where someone lives or the amount of time the light will be used, this is a very tough measurement to determine. However, it is a good way to compare one light bulb to another to decide which is more cost-efficient.


Again, this is determined by how often the light bulb is used, however, it is still helpful to know that what you are buying is long-lasting.

Light Appearance

In addition to “Brightness” and “Energy Used”, light appearance is an important aspect to note. As mentioned above, the color of light is determined using the Kelvin scale. This label has a temperature of 500K. A light bulb between 400K to 500K is traditional white light and gives off little color.

Energy Used

Such a low wattage (10.5) can tell us that this is an LED or CFL light. These lights use less wattage to achieve luminance. A traditional incandescent light would require around 100 watts to emit 800 lumens, whereas energy-efficient lighting like LEDs and CFLs can create the same brightness at a much lower wattage.

Trusted Professionals at Frye Electric, Inc.

Understanding light and electricity can be overwhelming, but we are always here to help. Whether your home is in need of electrical help or you just need the assistance of a professional, don’t hesitate to give Frye Electric, Inc. a call.