Bulb Type Differences for Safety Beacons and Signals

Understanding the Difference Between LED, Xenon, Halogen and Incandescent Bulbs

Which Bulb Type is Best for My Application?
Searching for the ideal safety signal can be overwhelming if you are unfamiliar with the types of light bulbs available. This article is intended to help you understand and compare various bulb types in order to find the best fit for your need. But first, let’s explain some terminology. 

Quick-Reference Dictionary

• Filament – Inner metal wire of an incandescent bulb that is heated to produce light. 
• Glass envelope – The glass casing of a light bulb used to contain the inert gases surrounding the filament. 
• Incandescent – Light produced or emitted due to high temperature. 
• Inert gas – A generally non-reactive noble gas.
• Lumens per Watt (Lm/W)– The total amount of visible light produced with a certain amount of electricity. In other words, the more lumens per watt a bulb produces, the more energy efficient it is.  
• UV emissions- Ultraviolet rays produced in the process of creating light. 

Incandescent Bulbs 
Incandescent bulbs are quite common and for many years have been the primary bulb type used in home lighting. Incandescence means producing or emitting light due to the high temperature of an object. Therefore, with incandescent bulbs, the inner wire (filament) is heated to such a high temperature that it begins to glow and emit light. The glass envelope surrounding it contains either an inert gases or is a vacuum (no gas), both of which prevent oxidation of the metal filament. Incandescent bulbs are not necessarily the most efficient bulb type, but they produce relatively low heat and UV emissions.

• 1,000-hour life span
• 8-24 lumens per watt
• Low to average heat
• Low UV emissions
• Warmer color (yellowish)

Halogen Bulbs 
Halogen lights are a type of incandescent bulbs, but the filament is made of tungsten and is surrounded by halogen gas. The tungsten filament and halogen gas produce a chemical reaction that essentially expands the life of the bulb and increases efficiency. As tungsten decays, the evaporated molecules bind with the halogen gas (usually bromine or iodine) to create tungsten halide, which redeposits onto the tungsten filament, thus creating a life-prolonging cycle. This process, however, requires higher temperatures to operate and increases UV emissions compared to standard incandescent bulbs. Additionally, Halogen bulbs are very delicate and should not be handled directly. Oil residue from hands can cause the glass envelope to heat unevenly and consequently shatter after time. For this reason, many halogen bulbs are enclosed in a larger glass casing to protect the bulb, minimize direct heat, and potentially decrease UV emissions if a UV filter is included. 

• 2,000-hour life span
• 10-35 lumens per watt
• Potentially unsuitable for some applications due to high heat and UV emissions. Not recommended for enclosed or frequently-used spaces. 
• Cool tone (more white than yellow)
• Avoid direct contact with bulb
• Generally more efficient than standard incandescent bulbs
• Accurately portrays colors with perfect CRI (color rendering index) rating 

Xenon Bulbs 
Like Halogen lamps, Xenon lights are incandescent bulbs with a tungsten filament; however, the enclosed gas is xenon rather than halogen. Xenon gas helps slow the decay of the tungsten filament and greatly extends the life of the bulb. When stimulated by electricity, the xenon gas also glows, therefore requiring less energy to produce the same lumen output as a halogen bulb. Xenon lamps are generally more efficient and longer lasting than Halogen or standard incandescent lights. They also produce less heat and fewer UV emissions.  Xenon bulbs are often used synonymously with HID (high-intensity discharge) bulbs. 

• 10,000-hour life span
• 50-90 lumens per watt
• Produce less heat than Halogen bulbs
• Low UV emissions
• Cool tone (White > Yellow), though slightly warmer in color than halogen
• Accurately portrays colors with perfect CRI (color rendering index) rating 

LED Bulbs
An LED (light-emitting diode) light, unlike any type of incandescent bulb, does not use a metal filament to produce light. Rather, it relies on electric current to rearrange electrons within a small semiconductor plate at the center of the bulb. As electrons transfer from the electric current to the semiconductor, energy is released in the form of photons (light). The color of the light produced depends on the amount of energy required for the electrons to relocate. Therefore, some white LED bulbs actually use several small semiconductor pieces of different properties that, when combined, produce white light. Other white LED lights use a phosphor coating that converts blue light into white light with fairly accurate color rendition. Compared to other bulb types, LED lights are generally the most efficient, longest-lasting, produce the lowest amount of heat and UV emissions, and have the largest light output. 

• 45,000-hour life span
• 100+ lumens per watt
• Low heat emission
• No UV emissions
• Any Color