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For safety and good ignition, earthing of the luminaires and the electrical
system can be essential. Check the system’s current to real earth (see
section 5.3.18: Earth leakage).The voltage between real earth and the
neutral conductor is not limited by safety regulations,but lies normally
between 0 and 6 V.
Apart from these electrical tests, it has to be checked that all
components are used within their specifications,with special attention
to the maximum temperature.
Installation aspects
- The live side of the mains must be connected to the ballast.As most
ballasts are symmetrical there is no marked indication at the ballast
terminals for the mains and lamp connection. Mixing up the ballast
terminals can slightly influence the radio-interference level.
- In the total circuit,however, interchanged connection of phase and
neutral terminals can cause higher radio interference, higher earth
leakage currents and/or ignition problems.
- It is recommended that the bottom plate of the ballast be
connected to earth, for example via a metal part of the luminaire. In
case of end-of-life of the ballast, short-circuiting of the ballast
windings to the metal laminations of the ballast will result in a blown
mains fuse.The ballasts do not have a separate earth contact:
earthing-while-mounting.
- In two- or three-phase networks with a neutral conductor, this
neutral wire must have the same cross-section as the phase wires.
- Use stranded wire in places that are subjected to vibrations or where
the wire must be able to bend in use, as in a spotlight.
- Most ballasts, starter- and lampholders are equipped with either single
or double insert contacts, suited for solid core wire of 0.5 - 1.0 mm
2
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which should be stripped properly.
- At ambient temperatures below 10 ºC closed luminaires should be
used to avoid too low lighting levels.
- Circuits with glow-switch starters require long starting times at low
temperatures.An earthed metal shield near the lamp will improve
the starting process, shortening the starting time and increasing
lamp life.This earthed metal shield can be the mounting plate for the
ballast.
- Mount the ballast as close as possible to the lamp.Although the
starter peak initially has a high value,its energy content is restricted.
Due to the high ohmic resistance of long installation wires, the
starter energy can easily be lost.This can happen in particular in series
circuits with two ‘TL’ 4-6-8 W lamps.
- Preferably mount ballasts on metal surfaces for good heat transmission.
If the ballast has to be mounted on heat-isolating material (wood),
the type ballast should be used.
- In outdoor applications SL lamps should be used inside an enclosed
luminaire.This is to prevent moisture from creeping into the lamp.
- SL lamps cannot be dimmed as this will reduce lifetime considerably.
Also, the dimming circuit in which the lamps are used can be
damaged.
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3.19 Fault finding