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T5 (16 mm)
fluorescent lamps
Question:
Why are two values given for the luminous flux of T 5
(16 mm) fluorescent lamps?
Answer:
Linear T 5 (16 mm) fluorescent lamps of the types FH and
FQ achieve their maximum luminous flux at a lamp ambient
temperature of 35¡ã C (-1 / +3 K), i.e. at a temperature
that results during operation in virtually all
luminaires for fluorescent lamps. This means that the T
5 fluorescent lamps are operated optimally, which is
also reflected in a higher luminaire efficiency. In the
standard IEC 60081 for fluorescent lamps, the luminous
flux value is generally defined at 25¡ã C, as this is the
planning basis and the basis for photometric
measurements. As a result, the luminous flux at 25 ¡ãC is
named as the nominal luminous flux for planning and
calculation purposes. This value is somewhat lower than
the maximum value at 35 ¡ãC in accordance with the curve
for luminous flux in dependence on temperature. This is
well-compensated via the considerably higher luminaire
efficiency, which plays a major role in the luminous
calculation. It is considerably higher for a luminaire
equipped with T 5 lamps than a luminaire equipped with T
8 lamps.
Luminaires with T5 lamps
Question:
What must be observed when using T 5 lamps in multi-lamp
luminaires?
Answer:
For lighting and operating reasons, a luminaire in which
the distance between the two linear lamps is
approximately double the lamp diameter (32 mm) is
recommended.
The linear lamps must be fitted so that the ends with
the type designation (stamp) are next to each other, and
on circular lamps the cap ends.
Burning in T 5
Question:
Are T 5 (16 mm) fluorescent lamps to be burned in?
Answer:
A burn-in time of 100 hrs. serves the basic
stabilisation of new lamps. When operating lamps on
dimmable ECGs, the 100-hour burn-in period of the lamps
must be carried out with the 100 % dimming position. If
the system is switched off again prior to measurement,
then burning in must be carried out again for 1 to 2
hrs.
Burning position of T 5 (16 mm) lamps
Question:
Can the new T 5 (16 mm) fluorescent lamps also be used
in any desired burning position?
Answer:
Yes, FH and FQ lamps can be used in any burning
position. Generally the luminaires are mounted on the
ceiling or hung from the ceiling so that a horizontal
burning position results for the luminaire. In cases in
which the lamps or luminaires are arranged vertically or
at an angle, the lamps must be fitted so that the end
with the type designation (stamp) is located at the
bottom (coldest necessary position for optimum luminous
flux at the bottom). With FC the circular T 5 lamps and
vertical arrangement, the lamp cap is to be located at
the bottom.
T 5 in exterior lighting
Question:
Can T 5 (16 mm) fluorescent lamps also be used in
exterior lighting?
Answer:
However, the maximum luminous flux which results for the
lamp at an ambient temperature of 35¡ã C with the FH and
FQ linear lamps also means considerably lower values of
the ambient temperature for the lamp, and with it a
lower luminous flux when the exterior temperature is
lower.
If an application of this type is necessary for T 5
lamps, then FQ lamps and suitable luminaires should be
used, as these lamps heat up the inside of the closed
luminaire faster than comparable FH lamps due to their
higher wattage.
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