The importance of testing devices for lamps
Lighting maintenance schedules usually demand that lamp testing be done quickly.
Fluorescents that are dark or flickering are replaced, and if that doesn’t do the trick the starter is next, then the ballast.
In large facilities such as commercial buildings and hospitals, labour and materials are wasted due to unnecessary haste.
However, using a tester is a great time saver. You can immediately establish whether a lamp ¬– neon, fluoro, mercury vapour, etc – is functioning, and gain a quick appraisal of what else may be contributing to any problems.
An efficient (no false positives or negatives) lamp tester suitable for low-pressure and high-pressure vapour lamps is not a luxury item. It’s a tool that gives an extra edge to the service electricians can offer their customers.
Of course, a practical lamp tester must determine the basic condition of the lamp, but it should be able to offer other checks so that contacts, ballasts, etc, can be given the once-over.
As far as the lamp itself is concerned, the basic operation is an induction test.
In the standard fluorescent lamp and other gas-filled units, hot filaments emit electrons, which ionise mercury atoms (fluoros) or other ionisable atoms in the vacuum of the lamp. In the case of induction lighting, it is a strong, high-frequency magnetic field that does the job.
The same technology is employed in a good lamp tester. By means of induction the tester is able to distinguish the basic operation of the lamp from the fittings and driving circuitry.
A useful tester should have sufficient field strength to ensure that gas in the lamp can be ionised reliably, and the frequency of the field should not interfere with communication devices.
It is also important to have a voltage test function, so that continuity testing can safely be done on the lamp’s driving circuitry and connectors.
A testing instrument should be checked for its suitability for neon, low-pressure and high-pressure sodium, and mercury and metal halogen lamps.