Updated 30-X-2011
Lamp Nomenclature
Fluorescent Colours
Early History
Operating Principle
Phosphor Types
Gas Fillings
Lamp Lifetime
Switching Frequency
Ambient Temperature
Operating Frequency
Dimming Operation
Lamp Designs
T12 Argon
T8 Krypton
T5 Krypton
T5 Miniature
(Very) High Output
Rapid Start
Instant Start
Non-Linear Tubes
Compact Fluorescent
Lamp Designs
Switch Start
Tandem Switch-Start
Semi-Resonant Start
Rapid Start
Instant Start
Resistor Ballast
High Frequency
DC Operation

Fluorescent Lamp Nomenclature

During the 1940s several nations and manufacturers introduced comprehensive systems of nomenclature to identify the many different kinds of fluorescent lamps which had become available. Some of the more commonly encountered systems are disclosed in the tables below.

British System
All codes begin MCF, the terminology for a low pressure mercury-fluorescent source, as defined under the general mercury discharge lamp nomenclature. Codes are sometimes followed by /U which indicates universal burning position.
MCF Standard fluorescent tube with no integrated starting features.
MCFA With external conducting strip connected to both caps, or otherwise intended to be at earth or fitting potential. For rapid-start circuits with autoleak transformer ballast.
MCFB With one internal conducting strip connected to one electrode. For circuits controlled by a filament ballast lamp or a resistor.
MCFC With external conducting strip not connected to either cap, i.e. not at earth or fitting potential. Intended to decrease resistance of the glass tube for easier starting. Superseded by type MCFE.
MCFD As MCFB/U, but with two internal strips connected to opposite electrodes and a small gap between the strips inside the lamp, for initiating the discharge.
MCFE With external water-repellent (silicone) coating, to facilitate starting on rapid-start circuits with autoleak transformer ballast, but also widely used for switch-start circuits.
MCFR Reflector lamps having an internal layer of reflecting material applied to about two thirds of the circumference of the tube, along its whole length.
MCFW Lamps made in Woods glass with UV-A emitting phosphor, designed for stimulating fluorescence in objects being irradiated.

Philips System
All codes begin TL, the original Dutch terminology applied to low voltage fluorescent tubes, as opposed to the high voltage tubes that wereformerly existent for cold-cathode signage applications. T=Tension (voltage), L=Laag (low).
TL - Standard linear fluorescent lamps for operation on ordinary mains voltages.
TL 'A' Aard (Earth) Standard Lamps with external earthed stripe connected to each cap.
TL 'B' Basse (Low) Special 40W lamp for low operating temperatures.
TL 'C' - For DC circuits from 80 to 140V with stabilising barretters in trams, trains and ships.
TL 'D' Dunn (Thin) Standard Lamps with reduced size tubes of 26mm diameter.
TL 'E' Ellipsoid Circular fluorescent tubes.
TL 'F' ReFlector Internal reflective coating.
TL 'H' Hoog (High) Amalgam tube for use in high temperature luminaires.
TL 'K' Kracht (Force) High current loaded tubes.
TL 'M' - External stripe connected via a high resistance to one electrode. For instant-start/dimming ballasts.
TL 'R' Relai (Relay) For DC circuits >140V with stabilising lamps and magnetic relays.
TL 'S' Starterless Starterless design with internal stripe, for use with series lamp or ballast.
TL 'U' U-Shape U-shaped fluorescent tube.
TL 'W' W-Shape W-shaped fluorescent tube.
TL 'X' EXplosion Similar to "TL" S but having special end caps for flame-proof equipment.
TL '5' 5/8 inch New standard long tubes having nominal diameter of 5/8 inch.

American System
First letter "F" denotes Fluorescent tube. A pair of numbers then denotes either the lamp wattage (for standard types), or the tube length in inches (for special types). A letter T indicates the tubular construction followed by the glass diameter in eigths of an inch. After a slash the colour is given, and finally any special features are indicated.
F Fluorescent XX Watts/Inches T5 5/8" miniature WW Warm White RS Rapid Start
FC Circular T6 6/8" slimline CW Cool White IS Instant Start
FU U-Tube T8 8/8" standard N Natural HO High Output
G Germicidal T12 12/8" standard D Daylight VHO Very High Output
T17 17/8" high power WWX Warm DX
TD17 17/8" dented CWX Cool DX
T10J 10/8" jacketed BLB Blacklight