er and positive contact with lamp pins.
If you used starters, check and replace each as necessary.
Examine the ballast leads to make sure the connection matches the diagram on the ballast label.
Examine and test the ballast. Leaking compound (except for a normal small amount at the lead holes), cracking or brittle insulation, or discoloration on the can may indicate the ballast (especially an electromagnetic type) is approaching, or has reached, the end of its life.
The Table (in the original article) offers general instructions for troubleshooting when fluorescent lamps do not start.
At the outset, we'll discuss two specific problems found in any type of fluorescent system. We call the first cycling. The National Electrical Code (NEC) requires most indoor ballasts to have a cutout device that protects them from overheating. If high ambient conditions cause the ballast to overheat, the thermal protection device's switch disconnects it from the power supply; if the temperature at the ballast is reduced, the cutout device closes, reactivating the ballast, thus restarting the lamps. If such a cycling condition persists, you must find the cause of the high temperature and correct it.
We call the second condition swirling, where the light appears to swirl or spiral inside the tube during operation. This normal occurrence can last for a few hours with some new lamps when first energized. However, a cold ambient temperature or low input voltage can also cause the problem.
Rapid-start (RS) systems. To measure the starting voltage of an RS ballast, connect a voltmeter between the highest reading Red lead and Blue lead with the lamp removed. See Fig. 2 (in the original article). Consider the following example: For an F 40 T12 two-lamp ballast, the minimum starting voltage is 256V. The minimum starting voltage for F96T12HO two lamp ballast is 466V. For a F96T12VHO ballast, it's 470V. All numbers are for minimum ambient temperature of 50DegrF. You should find these open circuit voltages on the ballast's label. (Note: Electronic ballasts generally provide starting voltages higher than their electromagnetic counterparts. You can also find their open circuit voltages on the ballast's label.)
To measure the filament voltage on a single lamp unit, read voltage between Red-Red and Blue-Blue leads. For two lamp units, read voltage between Red-Red, Blue-Blue, and Yellow-Yellow leads. For all 4-ft and longer RS lamps, the filament voltage should be between 3.5V and 4.5V. Sometimes with a two-lamp, RS series ballast only one lamp will light to full brilliance. Refer to Fig 2 again (in the original article). If the lamp between the Red and Yellow leads is lit and the other lamp is out, look for a pinched Yellow lead. If the lamp between the Red and Yellow leads does not light and the other one does, the cause is probably a short.
Why is good contact of lamp pins with their sockets so important? When an RS lamp circuit first energizes, the low-voltage winding of the ballast provides the cathode heating. Shortly afterward, the open-circuit voltage is applied across the lamp, or lamps, to begin arc conduction.
If only one cathode heats up, either the lamp will fail to start or it will be slow in starting. Heavy premature end-darkening, usually at only one end, usually indicates one cathode is not getting proper heat. Therefore, the heater circuit is incomplete. This is not the same as gray or brownish bands occurring about 2 in. from the lamp base, with the edge of each band on the side nearer to the base being sharper. These bands occur when the cathode coating wears out. While they may detract from the appearance of the lamp, moderately dark bands have no significance concerning either life or performance of the lamp. However, you should replace failed RS lamps promptly to avoid any possible ballast damage.
The lack of cathode heating voltage can come from a poor connection, either between the lamp pins and lampholder contacts, or between the ballast leads and lampholder terminals. Improper lampholder spacing in the lengthwise direction, with t