Symptom

Corrective Action

Fixture will not light or all lamps will not light. Also slow or erratic starting.

1. Check the lamps for proper seating. Index mark on lamp end cap should face out.
2. Read ballast label (under ballast cover) and markings for compatibility.
3. Replace bad lamps.
4. If 24" fixture or smaller has starter, reseat or change starter. (pre-heat fixtures only).
5. If the fixture is new, check the connections to the building service and check the fixture wiring against the diagram on the ballast case (black to black; white to white).
6. Verify the fixture is properly grounded. All fluorescent fixtures must be grounded for safety reasons and reliable starting.
7. Check line voltage. Must be between 105 and 125 volts AC.
8. 34W Energy Saving lamps will not work below 60 degrees F. Special low-temp ballasts are required to start 40W fluorescent lamps below 50 degrees F.
9. If the fixture is a 2-lamp Circline, both lamps must be used.

Reduced light output

1. Check the lamps for proper seating. Index mark on lamp end-cap should face out.
2. Read ballast label and lamp markings for lamp compatibility.
3. Replace bad lamps.
4. If 24" fixture or smaller has a starter, try reseating or changing the starter (pre-heat fixtures only).
5. Check ambient temperature. Extreme cold will reduce light output. Tube shields (OLS) will help in cold areas by helping the lamp to warm up.
6. Check for fans blowing extreme cold or hot air across the lamps.
7. Fixtures marked "For Residential Use Only" have a lower light output than fixtures with energy saving ballasts.

Blinking, snaking or flickering

1. Check ambient temperature and look for fans or air conditioning blowing cold air across the lamps. Tube shields will help isolate the lamp from ambient air currents.
2. New lamps may require a break-in period of up to 100 hours. Allow the lamps to remain on continuously for a time (24-48 hours).
3. Low supply voltage (under 105 volts AC) could also cause this condition.
4. Turn lamp around in fixture.

Radio interference

1. Move the equipment at least 10 feet from the fluorescent lamps.
2. Install Radio Interference Filters in the fluorescent fixture on the ballast supply leads. Filters are available through most electrical distributors.
3. Improve equipment ground and install shielded grounded cable to the antenna.

Fixture hums

1. All magnetic ballasts will hum to some degree. This is an inherent characteristic of this technology. Ballasts are sound rated from "A" through "D," with the "A" rated ballasts the quietest. Ballasts with "B" through "D" ratings should not be used in quiet areas where the hum would be objectionable.
2. Check the ballast mounting screws. A loose ballast will make noise. Tightening will help to fix this.
3. The conditions of the room where the fixture is installed will also contribute to the amount of noticeable ballast noise. Rugs, furniture, drapes all contribute to lower ballast noise levels. The lack of background activity makes noise more noticeable. Ballast noise is rarely noticed in areas with activity.

Repeated ballast cycling (off/on)

1. All ballasts for indoor use except for some pre-heat types are equipped with an automatic resetting thermal cutout designated "Class P". The purpose of this cutout is to protect the ballast from overheating. Once the ballast cools down to normal, the cutout will reset and allow the fixture to light again. To stop the cycling, the cause of the overheating must be found and corrected.
2. Read the ballast label and lamp marking for compatibility.
3. Check the supply voltage. A supply in excess of the rated voltage will cause the ballast to overheat.
4. Check the ambient temperature. Ambient temperature higher than 77 degrees F. may cause the ballast to overheat. Insulation placed over fixture will raise temperature.
5. Look for heating ducts directing hot air at the fixture.
6. The typical fluorescent ballast will reach its operating temperature in 6 to 7 hours of operation. The use of a ballast radiator (a piece of heavy gage aluminum made to fit over the ballast and sink the heat from the ballast) will extend the time required to reach its maximum temperature and stop the ballast from cycling. Ballast radiators will do very little for fixtures that are in operation for 24 hours a day.