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Wattage Rating
Fluorescent lamps are rated in watts much the same as incandescent
lamps. The standard fluorescent range is from 4 to 125W and is a
more limited range than other lamp types.
Voltage Rating
Fluorescent lamps do NOT have a voltage rating. Each fluorescent
luminaire contains a ballast that provides the correct voltage to
the lamp for the connected supply voltage.
Lamp Shape and unlit appearance.
All fluorescent lamps have a smooth tubular shape with an internal
phosphor coating. Blacklight Ultra Violet lamps are made of Woods
glass and have an almost black appearance when not operating. Gold
or Radar Red tubes (both obsolete) have additional filters so look
Yellow or Red even when not operating. All other tube colours look
the same white colour until the lamp is switched on.
Lamp
Dimensions
A fluorescent lamp has two important dimensions:
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Tube diameter
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Overall length
In Europe the dimensions are measured in millimetres but the
"T" reference is commonly used. When tube diameter is
part of the order code, eighths of an inch are used, but for most
lamps the diameter is obvious from the wattage.
Figure 2.18. Fluorescent tube dimensions.
Lamp Finishes Fluorescent lamp finishes consist primarily of
different phosphor coatings which cover a broad range of colours.
There are four main families of "White" fluorescent
lamps.
Standard Colours
These are older types of phosphor which have lower
efficacy, poorer lumen maintenance and worse colour rendering.
They should only be used to match existing installed lamps and
where lamp cost is more important than efficiency or quality.
Because of the language complication of describing the colours of
these lamps there is a two digit reference used in Europe, but
note the numbers are NOT an indicator of any performance
characteristic.
Initial Lumens
The light output claim for fluorescent lamps is described
as initial lumens and is measured after 100 hours burning, which
allows new lamps to stabilise. Light output is measured at 25
degrees Celsius in accordance with IEC 81 and 901. The new long T5
lamps are measured at 35 degrees Celsius.
Lamp
Life
The life of a fluorescent lamp varies
with:
The longer the time of operation per
start, the longer the lamp life. Standard
rated average life assumes 3 hours
operation per start.
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