Failure to Operate

• End of lamp life - voltage requirements of lamp exceed output ability of ballast
• Incorrect supply voltage - take voltage reading at fixture
• Open capacitor - result of electrical failure or mechanical damage.

Lamp Cycling

• Incorrect lamp - lamp wattage, voltage, burning position and type must be checked against fixture label to be sure proper lamp has been installed
• Incorrect supply voltage
• Photocontrol - problems result from electrical failure or from an incorrect amount of light reaching the cell. Cover eye of cell with electrical tape to verify fixture and cell operation. If fixture fails to operate, cell must be bypassed electrically to identify the problem. Reposition the fixture or use cell caps to regulate light.

Color Shift

• New lamp replacement - new lamps go through a period of seasoning which may last for 100 hours or more. The usual result is noticeable color variation between lamps. System will stabilize as seasoning period ends.
• Line voltage dips - identify distribution system loading. Cause is usually the starting of large motors or use of electrical welding equipment. Line voltage recorders will identify the problem. Mild dips cause color shift, while severe dips will cause fixture to go out.

Low Light Output

• Incorrect supply voltage
• Near end of lamp life
• Incorrect lamp

Tripped Breaker of Blown Fuse

• Shorted capacitor - direct result of electrical failure or mechanical damage. Most common result is transformer failure. Both capacitor and transformer should be replaced

Burned Transformer Coils

• Burned primary coils - the usual result of fixture connections to incorrect supply voltage. Repeated failure often in conjunction with capacitor failure may indicate short-duration, high-voltage spikes on distribution system. Use of scope and power company assistance usually required to identify spikes. Another probable cause of failure is shorted capacitor.
• Burned secondary coils - may be caused by a short circuit in lamp circuit wiring or by mechanical failure in lamp. Inspect lamp circuit wiring