Symptom

Possible Causes

Solutions

Lamp won’t light

Normal end of life

Lamp not seated in socket properly

Lamp is defective

Replace the lamp

Tighten the lamp; if this doesn’t work, pull out the metal contact inside the socket so that it makes good contact, making sure first that the fixture is de-energized

Replace the lamp

Short average life

High supply voltage

Lamps operating near neon tubing

Vibration or shock

Overvoltage significantly incandescent lamp life

Install metal shield between neon and incandescent lamps

Replace with rough-service lamp, which is more resistant to vibrations/shocks, or a compact fluorescent lamp

Deposit on inside of the glass bulb

Defective lamp

Air is entering the lamp through a crack; replace the lamp. Check for signs of moisture, which can result in cracks; replace with a silcone-coated lamp

Blistering/Bulging on bulb

High operating temperature

Check to make sure the lamp is the appropriate wattage for the fixture; replace with the right lamp. Also check for cracks; replace with a silicone-coated lamp. Finally, check for a manufacturer defect; replace the lamp

Symptom

Possible Causes

Solutions

Lamp does not light, or starts erratically or slowly

Lamps are not aligned/seated properly in their sockets

There is a lamp or fixture problem

Problem is with the ballast

Position lamps properly

Install a known good lamp to determine if the problem is in the lamp or fixture. If good lamps light, then check the removed lamps in a fixture that is operating properly

Replace the ballast

Lamps known to be good are not lighting (preheat ballast)

Manual reset starter is not reset

The starter has failed

Problem with ballast

Push button on starter

Replace the starter

Replace the ballast

Lamps known to be good are not lighting

Lamp and ballast are not compatible

Lamps are dirty

Starting aid (metal strip) is not properly positioned

Supply voltage is not right for the lamp

Problem with fixture wiring

Problem with ballast

Check the lamp and ballast labels and replace as needed (replace the lamp first)

Clean the lamps properly

Correct the starting aid’s grounding and positioning

Check the voltage

Check the wiring against the wiring diagram on the ballast label or manufacturer’s catalog, and correct as needed

Replace the ballast

Early lamp failure

Lamp has failed normally

Individual lamps do not fail in a predictable manner, only large groups of lamps do; at rated life, 50% have failed, and 50% will fail afterwards

Reduced average life

Frequent starting

HO/VHO incompatibility; for example, HO lamp may be operating on VHO ballast, which is incompatible

Frequent lamp switching reduces average life

Make sure lamp and ballast are compatible

Heavy blackening at ends of lamp and short lamp life

Defective lamp, open wiring or poor wiring in socket, poor contact in the socket

Problem with the ballast

Seat lamps properly; if they are already seated properly, then check for proper heater voltage at the sockets

Replace the ballast

One lamp is not lighting, the other is glowing only dimly on a two-lamp series sequence ballast

The lamp that is not lighting (second lamp in the series circuit) has reached normal end of life

Replace the failed lamp

Both lamps are out on a two-lamp series sequence ballast

The first lamp in the series circuit has reached normal end of life

Replace the failed lamp; if both lamps do not light, then there may be a problem with the ballast (also see "Lamps known to be good are not lighting")

Blinking (preheat ballast)

Normal end of lamp or starter life

Replaced the lamp or starter as needed

Ends of lamp are lighted but the lamp does not light fully

Failed starter

Replace the starter

Swirling, fluttering or spiraling effect in the lamp

Some lamps experience this during normal operation

Low ambient temperature

Lamp and ballast are incompatible

There is a problem in the ballast

Will stop after several hours of operation

Check the ballast label for minimum starting temperature; replace ballast with cold service ballast or jacket the lamps

Replace as needed

Replace the ballast