The performance of electric lamps will deteriorate with time. Eventually they fail and the lamps must be replaced.
Simple lamp replacement becomes the most obvious maintenance task. When a luminaire fails to light-up when switched on, it is natural to suspect lamp failure. If this does not solve the problem, checks on the lamp control equipment and power supply must follow.
An incandescent lamp may be checked (out of circuit) for low-ohm continuity using a multimeter. If the lamp appears intact then the fault must lie in the supply or its connections.
Voltage and continuity checks of the supply, fuse/ MCB and ballast circuit must be applied.
Remember that a single earth fault on an insulated two-wire lighting supply will not blow a fuse.
However, a similar earth fault on an earthed supply system (as used for a 110V transformer supply to deck sockets for portable tools and hand lamps) will blow a fuse.
The single E/F completes a low resistance path back to the neutral or centre point of the supply with a resulting large fault current to rupture the fuse.
Maintenance check list for ship’s lightning system:
Remember that it is good practice to replace both fuses after clearing a fault which has ruptured only one of them.
When replacing a lamp, ensure that the circuit is dead and isolated while removing the old lamp and inserting the new one. The glass bulb or tube of an old and corroded fitting may break loose from its end-cap while attempting to remove the lamp. If the supply is still connected, it is relatively easy to cause an accidental short- circuit during the removal process and the corresponding arc flash may cause blindness, burns and fire.
Always replace a lamp with the correct size, voltage and power rating for the fitting it is housed in. Overheating and fire can easily result by using a higher powered incandescent lamp than the fitting was designed for. Check the lamp holder wire connections behind the lamp holder for signs of overheating (hard, brittle insulation on the wires) and replace if necessary.
Take care when disposing of lamps, particularly discharge tubes, which should be broken (outdoors) into a container (e.g. a strong plastic bag) to avoid handling the debris.
Remember that in a fluorescent lamp circuit the capacitor may remain charged for a while after switch off unless fitted with a discharge resistor.
Play safe, discharge the capacitor with a screwdriver blade before touching its terminals.
Cleaning of the lamp glass and reflectors is essential for safety and necessary to maintain the luminous efficiency of the luminaire.
Particular care should be paid to the maintenance of the watertight integrity of exposed luminaires (navigation, signal and deck lighting) at their flanged joints and cable gland entry.
Similarly, a regular inspection of all portable hand lamps and portable cargo light fittings, together with their flexible cables and supply plugs, should be undertaken.