Elementary electrical components verification

Elementary electrical components verification

LAMPS

A lamp is characterized by voltage and nominal power.

The lamp resistance decreases in proportion to the increase in power: for example, a headlamp bulb (12V-45W) will have a lower resistance than a cluster warning light bulb (12V-3W).

If it is not possible with a visual check to find a broken filament, it is necessary to check the bulb integrity removing it and connecting the terminals to the ohmmeter tester tips: a “finished” resistance value (higher or lower according to the power) indicates a lamp in good condition, whereas a very high resistance value (“infinie”) means that the bulb filament is broken.

Halogen lamps: halogen lamps have the bulb in quartz, not glass: grease on the bulb surface, due to the high operating temperature, causes “devitrification” of the quartz, and consequent degradation of the lamp brightness characteristics.

Therefore the halogen lamps are to be handled grasping them only by the metal neck, carefully avoiding to touch the bulb with the fingers: if this does happen,carefully clean the bulb with heptane or an equivalent degreasing product.

FUSES

The fuse is an electric conductor that has a section that “melts” interrupting the circuit if the load on that cable exceeds a certain limit, referred to as the fuse “Amperage”.

If visual checking does not indicate clearly the condition of the fuse, it can be checked by connecting its terminals to the ohmmeter tester tips: a nul resistance value indicates a fuse still in good condition, whereas a high resistance value (“infinite”) means that the filament is broken.