Fluorescent lighting explained

Submitted by: Jonathan Ramayia, Wednesday, January 25, 2012

Lighting technologies are various, extensive and downright confusing for business and homeowners. This post explains just one of those lighting technologies, fluorescent lighting, and looks at the technology and the energy efficiency of this particular type of lighting technology. Fluorescent lights are often touted as the alternative to incandescent lights.

Incandescent lights are those ‘normal’ lights with a yellow glow that were used in most South African homes and businesses before Eskom’s CFL programme was introduced in the mid-2000s. The two common types of fluorescent lamps are the compact fluorescent lamp (CFL) and the long tube lamps known as T-lamps which essentially employ similar technology.


Fluorescent lights rely on electricity charges to ‘excite’ the mercury in a particular lamp in order to create a glow. On the other hand, incandescents have a tungsten filament housed inside a glass cover. Fluorescents are more favoured over incandescent for their energy efficiency mainly because they are able to produce light without needing to produce as much heat (test this by trying to touch a fluorescent versus an incandescent). Fluorescent tubes in particular are used in offices, workshops, schools and large rooms especially those with high roofs. Unlike incandescents, fluorescent tubes rely on a series of chemical and physical reactions where mercury atoms are excited by the incoming electricity to produce light. Therefore the internal composition of a fluorescent tube is very different from a “normal light”.

Each tube consists of the following

-          Glass tube

-          Contact pins

-          Electrodes at either end

-          A gas mixture containing a bit of mercury and an inert gas, usually argon

-          Internal phosphor coating

Efficiency and cost

Fluorescent lamps are 4-6 times more energy efficient than incandescent lights and produce less heat because of the technology it employs. Flourescents are more expensive than their equivalent incandescent but last much longer and also consume less electricity. However, CFLs are not as efficient and have a shorter life span than Light Emitting Diode (LED) lights that have started to enter the market. LEDs are also much more expensive than CFLs.

Hazardous waste

Although fluorescent lamps are more energy efficient than incandescents the fact that they contain mercury in their casing makes their disposal an environmental hazard. If a fluorescent tube is disposed of in a landfill site the mercury might leak out and infiltrate into the ground polluting rivers and other hydrological systems resulting in a negative impact on fish and the food chain. South Africans can dispose of their CFLs at selected Woolworths and Pick ‘n Pay stores. To find out more about where to dispose of other fluorescent lamps you can contact the e-Waste Association of South Africa (eWASA).

Jonathan Ramayia