Ballasts: 20 of 21
.
One of the first questions that occurs when you encounter a problem is: is it a lamp problem or a ballast problem?
The Lamp Swap Test
(1) Simply replace the lamp with a known good lamp--usually taken from a neighboring fixture where it is performing well (or from a box of new lamps) and see if the problem goes away.
(2) If the new lamp doesn't work but is known to be a good lamp (e.g. it worked in another socket), perhaps there is something wrong with the ballast or with the electrical connections between the ballast and the lamp. Check the old lamp in a new socket that is know to work well; its behavior will give you further information.
(3) Unless you are trained in this area NEVER
TRY TO CHECK THE VOLTAGE AT THE SOCKET WITH A METER! Ballasts
contain high voltages that could be lethal both to humans and to meters.