Bright Ideas

The Five Most Common Electric Light Sources

Posted by Joe Lightman on Jan 27, 2016 4:35 PM

How well a luminaire (fixture) performs, depends a lot on the type of light source (bulb or lamp) used. Different bulbs have different lighting effects, performance and pros and cons. Probably the biggest driver of innovation in light sources is energy efficiency, with LED technology leading the charge.

In this post we cover the most common electric light sources used in residential, commercial and industrial lighting including: how they work, pros and cons, applications, average rated life and cost.



1. Incandescent 

This is the original light bulb that Thomas Edison invented in the 1870’s. The technology behind it has changed little since then.  Incandescent bulbs produce light when an electric current passes through a thin wire (filament) causing it to glow. They are also called general service, A-lamps or A-19 lamps. Reflector or parabolic reflector (PAR) lamps, also known as flood or spot lamps are a variation of an incandescent.Thomas_Edison_Incandescent_RAB_Design.jpg

Pros: Incandescent bulbs have a low initial cost, put out a warm, inviting light, are dimmable and can handle different wattages - up to specified maximums - in the same socket.

Cons: They use a lot of energy, of which less than 10% is used for light. The rest is emitted as heat. A 100 watt light bulb generates enough heat to bake a cake in an old Easy Bake Oven toy. Incandescent bulbs are also not too hardy, unless they are rated as “long-life,” the filament is easily damaged.

Applications: Since they are less energy efficient than other light sources, they are best used for task lighting that requires high levels of brightness, for decorative use or where a warm light and colour is more important than.

Average Rated Life: Typically 700 – 2000 hours.

Cost: Typically they have the lowest initial cost of all light sources.

2. Halogen

Also known as tungsten-halogen, Is a type of incandescent bulb that has been around for 50 years.  Halogen filaments (made from tungsten) are housed in smaller quartz bulbs filled with halogen gases, such as iodine or bromine, which increase the efficacy (measure of emitted light) of the lamp versus a plain incandescent lamp. Halogen bulbs are available in two types: line voltage - meaning the voltage in a typical wall outlet (120/220 volts) - and low voltage (12 volt).

Pros: They are more energy efficient (up to 30 percent) providing more light per watt than standard incandescent bulbs and last 2-6 times longer than. They emit a bright clear light that is closest to daylight. Colours are sharper with halogen light, which can also be dimmed. The optimal Halogen option is the more efficient (IRC) infrared coated bulb, which produces more light for the same amount of energy.

Cons: Halogen lamps are more expensive than standard incandescent and burn at a higher temperature. They are highly sensitive to touch; oil residue from a person’s hand can rub off on the bulb, causing the bulb to heat up and explode.

Applications:  Typical halogen lamp applications include: residential, decorative, task lighting, stage lighting and retail.  They are also often used in under-cabinet lighting, pendant lights and recessed fixtures; in many cases they are being replaced with LED light sources which last longer and are more durable.

Average Rated Life: Typically 2,000 – 4,000 hours

Cost: Initial cost is higher than incandescent, but lower than LED, however halogen bulbs may need frequent replacement.

3. Fluorescent 

Is a low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. Fluorescent bulbs were widely introduced at the 1939 World’s Fair in New York City. They developed and evolved in response to energy crises and were quickly adopted in military, commercial and industrial spaces. The initial fluorescents were Linear (plug-in), followed by Compact Fluorescents (screw in) which became popular in the mid-1980’s as a replacement for incandescent bulbs.

Pros: Fluorescent lamps convert electrical energy into light more efficiently than incandescent lamps.  They give off a quarter the amount of heat of an incandescent (less energy) and last 10 times longer. Fluorescent improvements since the 1980’s have made them start faster, quieter, with warmer colours and some are dimmable.

Cons: Fluorescent lamp fixtures are more costly than incandescent since they require a ballast to regulate the current through the lamp. However the lower energy costs can offset the higher initial cost. Because they contain mercury, they are classified as hazardous waste and need to be disposed of properly.

Applications: Linear fluorescents have typically been used in various commercial, industrial spaces and applications with CFL’s (with integrated ballasts) becoming widely popular in residential applications due to energy saving and lower maintenance costs.

Average Rated Life:  

Plug-in/Linear: Typically 24,000 to 36,000 hours

Screw-base/Compact Fluorescent (CFL):  Typically 8,000 to 10,000 hours

 Cost: Initial purchase costs have dropped significantly which provide a cost/value that is hard to beat. 

4. HID (High Intensity Discharge Lamps )

HID lamps are a type of electrical gas-discharge lamp which uses a capsule of gas instead of the filament used in an incandescent lamp. The light is produced from an arc discharge between two closely spaced tungsten electrodes and through a plasma or ionized gas. They also use an additional gas with serves to classify the main types of HID lamps: Mercury Vapor, Metal Halide and High Pressure Sodium. HID lamps require a ballast which regulates the voltage supplied to the capsule of gas, allowing the light to start.

Pros: The amount of light produced by an HID lamp is greater than a standard halogen bulb and it uses less power.  They are also known for a long rated life.

Cons:  HID lights require time to warm up and the aesthetic quality of the light is not that great – typically cool white/blue or warm white/yellow.

Applications: HID lamps are used primarily in locations where it’s important to get as much visible light per watt for large areas, such as in for streetlights, gymnasiums, warehouses, large retail facilities, stadiums and for growing plants indoors.

Average Rated Life: 10,000 to 24,000 hours

Cost: Initial costs are lower than some other light sources, but HID’s require regular lamp and ballast replacement.


5. LED (Light Emitting Diode)

LEDs are a semiconductor typically made from silicon.  As electrons pass through the LED, it turns into light. LEDs are more efficient at turning energy into light compared to incandescent, CFL or halogen bulbs since less energy radiates from the bulb as heat. The term SSL (Solid State Lighting) is common term for LED technology being used for lighting applications. It refers to technology in which the light is emitted by solid-state electroluminescence as opposed to incandescent bulbs, where the light is emitted via thermal radiation.

Pros – They are highly energy efficient and last much longer than incandescent or fluorescent bulbs.  They also emit light in a specific direction. They contain no mercury, lead, gas or toxic substances. They also have no failure prone moving parts and can withstand a greater amount of vibration compared to traditional light sources

Cons – The cost is typically significantly higher than other light sources, but innovation and competition is bringing the cost down rapidly.

Applications:  LEDs are rapidly replacing other light sources for most general applications including indoor, outdoor and commercial usage. Other common usages include: automotive headlamps, horticulture and for backlights and display.

Average Rated Life: 40,000 to 100,000 hours

Cost: While the initial purchase cost of LEDs is higher than other light sources, maintenance costs are very low. There are also opportunities for rebates depending on your region, which can significantly reduce the payback period of an LED investment.Light_Sources_RAB_Design_Blog.jpg

There is a lot of freely available information out there covering light sources.  The U.S. Office of Energy and Renewable Energy (EERE) provides a helpful summary comparison table covering the most common light sources. Check it out here.

If you have any questions about your project, we are happy to help. RAB Design offers free lighting consultations, where one of our lighting specialists will work with you to answer questions about energy considerations, cost management and fixture selection.  We can also create a customized blueprint for your project. Click the button below to schedule your consultation.

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Topics: Commercial and Industrial Lighting, Lighting Essentials, Light Sources