Troubleshooting Light Bulbs, Lighting Fixtures, and Lamps
Who are the “Top Three” light bulb manufacturers?
Troubleshooting incandescent light bulb issues
Troubleshooting halogen lamping issues
Troubleshooting fluorescent lamp issues
Troubleshooting mercury, metal halide and sodium lamp problems
The “Big Three” light bulb manufacturers generally refer to General Electric, Osram/Sylvania, and Philips in the United States. These three companies are the main manufacturers of quality light bulbs in the USA.
Please note that in many cases store brand light bulbs having similar lumen light output figures and the same hour life expectancy figures as bulbs from the “Big Three” are also produced by the same top three manufacturers then given a private label for the designated retailer.
The most popular of the “Big Three” “regular” (A19) light bulbs are:
100 watt, with a 750 hour average life span and 1670-1750 lumens average output over the life of the bulb. These bulbs are ideal for reading and task light.
75 watt bulbs having an average life of 750 hours and an average output of 1150-1210 lumens. This brightness is good also for task lighting and reading.
60 watt bulbs with an 1000 hour average life, 840-890 lumens average output and can be used for ambient or soft task lighting.
40 watt with 1000-1500 hours bulbs that have 440-505 lumens average light output are best for ambient lighting.
Light bulbs from other manufactures that do not have these same specifications may produce less light than the “Big Three” bulbs listed above.
Incandescent bulbs that Burn Out Too Quickly (See specific lighting issues below):
Excessive voltage in your electrical lines may be the problem. Test your sockets with a voltage monitor sold online or at a local electrical supply store. Call the local utility company if you can determine excessive voltage is the issue. A professional electrician may need to be called in to manage excessive or weak line voltage.
Moderate your expectations for the life of the bulb. A 750 hour bulb that is in use six hours a day will normally burn out in about four months. If you have several of these bulbs throughout the home, installed at different times, you might be replacing bulbs once a month or two.
Avoid discount light bulbs and those sold with non store brand or “Big Three” labels. They may not have the same quality and longevity.
Light bulbs installed in Recessed Ceiling Fixtures Burn Out Too Frequently
Make sure that the bulbs are designed for recessed lighting recessed lighting. Use only the recommended wattage suggested by the manufacturer of the recessed lighting. Built up heat in these fixtures can shorten the life of the bulb and light.
Small Enclosed Fixture Light Bulbs Burn Out Too Quickly:
Heat can build up quickly in an enclosed lighting fixture. Never exceed the recommended wattage of the fixture manufacturer. The maximum wattage should be displayed on a sticker mounted to the light fixture.
Off-brand bulbs should be avoided. Stick with name brand or store brand light bulbs.
Light Bulbs in Ceiling Fixtures Burn Out Too Quickly:
Enclosed ceiling fixtures often have a maximum wattage of 60 watts to avoid overheating. Do not use higher watt bulbs unless they fall under the maximum number of watts as suggested on the manufacturers label on the light.
Light Bulbs in Desk Lamps or Table Lamps Do Not Last:
Many desk lamps use halogen lights which have a long life but produce a great deal of heat. Even incandescent bulbs will produce heat in a desk lamp or table lamp. Keeping these lights on for 8 hours during a work day can create excess heat. Turn off a desk or table lamp during a lunch break or when you leave the office to conserve energy and the life of the bulb. For halogen bulb issues, see below.
Light bulbs that Burn Out Prematurely or Have a White Smoky Appearance
When air enters a light bulb through a crack it will oxidized the filament.
A crack due to heat or a dropped bulb can allow air into the bulb.
Cracks can be cause by water hitting a hot bulb.
The bulb overheated from excessive heat caused by the wrong type or wattage.
The lamp was knocked over but the bulb did not break completely. The filament could be broken, which can be heard when the bulb is shaken.
Condensation on a bulb results in thermal stress where dry parts of the bulb get excessively hot.
Light bulbs Break During Use:
See the section above
Long-life Bulbs Don’t Last as Expected:
Bulb may be an off brand with lower quality. Replace with a top brand or reliable store brand light bulb designated as “long life” or “extended life”. Check how long each day the bulbs are used to verify shorter life expectancy.
Light bulbs Get Dim or Flicker:
Check for corrosion at contact between the bulb and the socket or at the plug and outlet.
Check for a poor fitting contact or mashed-down socket contact. With power off it is possible to lift up the center contact to improve the connection.
Do not over tighten the bulb when installing it.
Check for poor contact in the fixture itself or in the outlet. Wires may be screwed down too loosely. This is good option if you have already replaced the bulb and the problem persists.
On a floor or table lamps, replace the socket. On a fixture, you may need to replace the fixture if the wiring is not the issue.
NOTE – Flickering with dimming can be a sign of a bigger, more serious issue. There could be major heat production in the wiring at the point of resistance due to poor contact, resulting in a fire hazard. A licensed electrician should be called.
Light Bulbs Gets Brighter Sometimes:
This can indicate a broken or poor neutral connection within a main or subpanel. Verify that the screws in the fuse box, breaker box and panels are sufficiently tight. Calling a licensed electrician to inspect the main and subpanels is a good idea as this may indicate a dangerous condition that could result in an electrical fire hazard. Inspecting the panels and making adjustments should be done as soon as possible.
Light Bulb Breaks or Pops Off The Base When Burnt Out:
A light bulb breaking when it burns out or popping off of its base can be the result of a lack of internal wire fuses. When a current surge occurs during a “burnout arc” it can reach hundreds of amps, which causes the wiring in the bulb to literally explode. This is a rare occurrence and can be a manufacturing error.
Light Bulbs that Damage Dimmer Switches or Electronic Switching Devices as they Burn Out:
The dimmer switch was not able to handle the current surge created by the “burnout” arc. A studier, better quality dimmer switch or electronic switching device should be purchased.
The light bulb may lack an internal wire fuse. (See section above)
To avoid this, some homeowners and electricians might replace the triac (or SCR) inside the dimmer with one having a higher current capability and trigger current no higher than the original. Using a triac or SCR with slightly higher trigger current than required should be done at your own risk.
Light Bulbs that Burn Out Too Fast in Certain Fixtures or Rooms:
Review the bulb to makes sure it is the right style and wattage for the light fixture.
Replace discount or off brand bulbs with a name brand or store brand bulb from a reputable store and brand.
Make sure bulbs and fixtures are not exposed to excessive heat, movement or being knocked over as the filaments may be jarred loose and shorten the life of the bulb. ceiling lights may be jostled by movement from the floor above. Vibration resistant bulbs may be a good choice.
Light bulbs Seem Dim
First, check line voltage if possible. If necessary, upgrade the wiring or shift loads on the panel. Call a licensed electrician for any work you are not qualified to perform. If the problem is not the panel, contact the utility company if it is beyond your panel or electrical meter.
Long-life bulbs can be dimmer than standard-life, even by top brands.
130 volt bulbs will be dimmer than 120 volt bulbs. The difference is typically 22-25%, which can be more if the 130 volts bulb life is longer than “standard life”.
Specialized bulbs, such as vibration or shock resistant bulbs or those having a rough service filament design, often are less efficient than standard bulbs and produce a dimmer light.
Projector Bulb or Photoflood Bulb Burns Out Quickly:
The average lifespan of these bulbs is often very short and can range from two to sixty hours.
Bulb is misused. The proper bulb in the right equipment can extend the life of these specialized bulbs. Following the wattage maximum, cooling requirements and usage suggestions on the equipment is essential.
Halogen Bulb Blackens And Burns Out Too Quickly:
Halogen bulbs must reach an optimal operating temperature for the chemicals inside to work properly. This means they are not ideally suited for refrigerator lights or lights in closed spaces such as closets.
Sometimes Halogen lights will do this when dimmed or put on a dimmer switch, which can shorten the life of these styles of bulbs if improperly operated or installed.
Excessive heat can shorten the life of these bulbs. In halogen desk lamps, turn off the lamp periodically to allow the bulb to cool.
Bulb may have been cracked as a result of contamination to the quartz. (See below for further information.)
Halogen Bulb which Cracks or Explodes or Burns Out that has a Smoky Appearance:
Because of the heat given off by the quartz bulb, halogen bulbs have a slight risk of doing this under optimal operation. More than likely there is a crack in the bulb from a stress point caused by contamination.
Contamination from salt, ash or alkali can leach into the hot quartz and result in strains that cause the bulb to crack.
Avoid touching the bulb, especially with bare hands.
Contaminated bulbs should be cleaned with a paper towel or clean cloth with distilled water or rubbing alcohol to remove grease or oil. When handling a halogen bulb, it is ideal to use the original packaging as a guard between bare hands and the bulb. Avoid touching the glass of the bulb.
If the halogen “capsules” are protected by an outer glass bulb, contamination is not an issue unless the outer bulb is broken.
A bulb may have subtle cracks from excessive or unintended force applied to its base or the connection points during installation.
Darker smoke color can indicate excessive age or a low quality bulb. Lighter colored smoke usually indicates a crack in the bulb.
TROUBLESHOOTING FLUORESCENT LAMP PROBLEMS
Burnout, Blinking and Glow Issues
Light Output and Color Problems
Burnout, Blinking and Glow Issues
Fluorescent Bulbs Burn Out Quickly:
The issue could be a bulb and ballast mismatch. Read the ballast label and check the markings on the bulb. Please note that 34 and 35 watt bulbs also may say F40T12 (color code) and “energy saver”.
The ballast could be defective or low grad. With an AC ammeter the ballast can be checked for excessive current consumption based on stated amp figure. This could be a sign of a bad ballast.
Turning the light on and off too many times causes wear on the ballast.
Corrosion has created poor contact with the bulb. Twisting the bulb may break up the corrosion temporarily. If corrosion is visible, turn off the power to the fixture and gently scrub off the corrosion on the socket contacts or bulb pins with a fine grade sandpaper. If there is a lot of corrosion on the socket contacts, a new fixture is needed.
Sometimes “shop light” bulbs have a shortened life designed by compromising longevity for extra energy efficiency and or lower cost. Replace with a standard fluorescent bulb if compatible with the fixture ballast. Avoid cheaper “shop light” fixtures as the ballasts may wear out the bulbs more quickly.
When Bulbs Die In Pairs – Is It The Ballast, One Bulb or Both?:
Often ballasts control the bulbs as pairs. The bulbs are operated in series together. Both bulbs may go out or dim at the same time if one bulb does.
In some fluorescent lights there is a “bleeder resistor” or another auxiliary component that will apply the full ballast output voltage to a single bulb if the pair is not conducting together. This helps the pair of bulbs start. With the “bleeder resistor” one bulb can glow very dimly and the other bulb be out. In this case it is possible that the dim bulb is the bad bulb and the darkened bulb still good.
The bad bulb typically has noticeable darkening of two to three inches at one end. Spot, blotching or a dark ring or band at one or both ends of the bulb is not a sign of a spent bulb.
Often prolonged use with a dim glow can damaged a good bulb. Long use of the filaments at elevated but less than normal temperatures can be damaging even to a new bulb. Check both bulbs with the new replacement bulb for best output. Avoiding dim glow damage may mean replacing both bulbs of the affected pair.
Bulb Is Very Dim or Out But Ends Glow a Dim Orange:
Replace the bulb. A rapid start ballast or a trigger start is heating the filaments to a temperature where they visibly glow, but the bulb is dead.
Bulb Blinks Infrequently – Once Every Few Seconds to a Few Times a Second:
Replace the bulb as the preheat bulb has died. Remove the bulb from the fixture as the blinking is difficult on the starter. The ballast can get stressed as the starter gets stuck in a starting loop. Continued blinking for a longer period of time may have caused damage to the starter as well and it should be replaced, even if the bulb is not yet out.
Bulb in Fixture With a Starter Glows at the Ends, Either Off-Color or Orangish; Sometimes Each End Glows a Different Color
Both the starter and the bulb are bad. If the bulb is new, a stuck starter may be the cause. A stuck starter can damage a new bulb so the bulb should be removed from the fixture until the starter can be replaced. If the bulb is not brand new, replace it at the time the starter is replaced. Just like a bad starter can ruin a new bulb, a bad bulb can ruin a new starter.
WARNING – Excessive current flowing through the ballast due to a stuck starter can overheat the ballast and fixture. Fires can be started. Bulbs that glow only on the ends or blink with only an end glow should be removed immediately. The glow can be yellow-orange, a bright orange, or a milky orange-glow as well as a normal bulb color.
Different color glows can indicate different issues. A near-normal bulb color end glow can indicate an arc across filament. The incandescent-orange color present indicates a lack of this arc. Filaments that glow bright yellow-orange to milky-orange-yellow without a sign of arcing are most likely worn beyond usefulness. Temperature will usually not vary much whether an arc forms or not. In the best case, remove these bulbs.
Bulbs Go Off Every Few Minutes or a Few Times an Hour:
The thermal cutout switch is over hearting in the ballast. The ballast could be bad or the wrong bulb is being used. Another cause can be that the ballast and or fixture is not properly mounted. In the case of some “shop light” designs, the fixture needs to be suspended to allow heat to escape rather than flush mounted to the ceiling. If a “shop light” is to be suspended, hooks and chains should be included from the manufacturer.
Fluorescent Fixture Does Not Start In Dark:
Some starters may depend on the photoelectric effect to work. Replace the starter with a different brand that contains trace amount of radioactive material that doesn’t require light. Glow in the dark paint or material placed near the starter can help.
Fluorescent Lamp Only Starts When Bulb is Touched or Brushed or Subjected to Static Electricity:
Many fluorescent lights require that the fixture to be grounded and the bulb to be mounted within a 1/2 inch (or 12.7 millimeters) of the grounded reflector or a grounded sheet conductor. Fixture may require that black wires are “hot” and white wires are “neutral” (Within the US). These issues may affect the electric field distribution with a bulb as it is started.
Other causes may be aging bulb, a bulb and ballast mismatch, cold temperatures, corrosion on the socket contacts, a bad ballast, low quality ballast or low line voltage issues covered elsewhere in this section.
Bulbs Fail To Turn on in Cold Temperature:
Although this is not a common problem, rapid start and instant start fluorescent lamps are supposed to have special low temperature ballasts for starting in the cold. You’re on your own with preheat ones, but try a different brand of starter.
If a low temperature capability ballast is being used properly, check the connections, the grounding on both the fixture and reflector or another sheet conductor that is within 1/2 inch of the bulb. Also check for commons issues such as bulb to ballast mismatch, low line voltage, corroded contacts, etc.
Starting is Unreliable:
For a fixture that has a dual 20 watt trigger with reduced output combined with flickering or just flickering, the issue may be with the ballast design or quality. Replace the bulbs with a different brand. Fixture may need to be replaced entirely.
Unreliable starting can be from a host of problems discussed elsewhere here. These include old bulbs, mismatched bulb and ballast, ungrounded fixture, fixture lacking a grounded reflector, light-required starter, bad or poor quality ballast or line voltage issues. Review other solutions.
Fluorescent Bulbs Look Dim or Have Light Output or Color Problems
Bulbs may be cold as cold or drafty environments can negatively affect the light output of these fixtures. “Tube guards”, plastic sleeves placed around the bulbs, can be used to build up heat in the bulbs. Sleeves do not help start the lights in cold temperatures, only insulate them to allow them to reach proper operating temperatures. Cold temperature starters are recommended. Sleeves should not be used if the bulbs are running marginally cooler than optimum as they can create excess heat. This applies to fluorescent under cabinet lighting in garages or unheated basements too.
For cool or drafty environments, enclosed fixtures are recommended over open fixtures. These enclosed fixtures allow for adequate heat build up in less severe cold temperatures in basements and heated garages.
34 watt energy saving bulbs may be more vulnerable to cold.
Broad spectrum bulbs, including deluxe models, typically produce a little less light output than standard and “triphosphor” bulbs.
Avoid off-brand ballasts. Ballasts made in North America, Europe or Japan are recommended. Top brands include: General Electric, Valmont, Magnetek, Robertson, Universal, or “iron” rapid start ballasts from Japan.
Using 25 watt “shop lights”. Switch to 40 watt bulbs for more brightness.
Worn phosphors in aging bulbs can affect light output or color. Replace with new bulbs if existing bulbs have not been replaced after many hours of usage.
Reminder: Check for a proper bulb and ballast match.
Below are issues and problems listed by specific lamp type.
20 Watt Fluorescents Look a Little Dim in Fixtures With Starters:
With fixtures having common 14-15-20 watt ballasts, 16 to 20 watts are usually delivered. Not very much can be changed about this. Do not rig up something to increase voltage in the fixture since that can overhead the ballast.
Low or Irregular Output in a Dual 20 Watt Fixture Without a Starter:
The issue could be with the “trigger” start in a typical dual 20 watt design. Replace with a different brand of bulb or replace the fixture with a different design.
20 Watt Lights from America Fixture Appear Dim:
The Lights of America ballast is semi-proprietary. This fixture has issues with delivering non-optimum current waveforms. Unfortunately there are no solutions to this problem.
20 Watt Fixture of Another Brand Looks a Little Dim:
The ballast possibly is supporting a 15-20 watt output, not a full 20 watts. Nothing can be done about this.
14 Watt Fluorescents Look Dim:
The nature of 14 watt fluorescents is that they are less efficient than 15 and 20 watt bulbs. Replacing the bulb with a 15 to 20 watt or even a “twin-tub or PL compact fluorescent in 13 watts is one suggested solution.
4 foot T8 32 Watt One Inch Diameter Low Mercury Lamps Are Dim:
The issue could be exposure to drafty or cold environments. The higher “electron temperature” or kinetic energy of free electrons cause by reduced mercury vapor content could be the issue. The mercury ions embed in phosphor particles, or in 184.9 nm UV shortwave and damage the phosphor.
Enclosed fixture may be a simple solution. Clear plastic protective “tube guards” can be used to build up heat. If the tubes brighten and dim during warm up with the “tube guards” over heating may be an issue. Removed “tube guards” and use just an enclosed fixture.
Fluorescent Bulbs Appear to be Different Colors:
Fluorescent bulbs are sold in a variety of colors. When buying replacement bulbs, match the color codes, color type, or color temperature to your existing bulbs. Be aware there are minor variances in color between batches and brands.
There are five major common colors in fluorescents based on temperature:
- 3000 warm white
- 3500 whiter warm white
- 4100 cool white
- 5000 pure white, cold
- 6500-6800 daylight or cold bluish white
Colors Appear Different Under New Fluorescent Bulb than Old Bulb
Spectral character can be different even if color and temperature is matched between old and new bulbs. Color rendering index is typically 80-86 but a related class has a color rendering index found in the mid-upper 70’s. Spectral categories for white fluorescent bulbs are:
Halophosphate – cool white and warm white, poor color rendering
Broad Spectrum – improvement over halophosphate, with reduced light output
Triphosphor – full light output, better and brighter color rendering
High Pressure Sodium Lamp Goes Out for 1-3 Minutes Even After Warming Up:
When a bulb goes out after the lamp warms up and has a dim orange-yellow before it relights, it typically indicates “end of life cycling” and is a bulb issue. Replace the bulb should fix the problem.
Less common but if the new bulb has the same issue the problem is with the reflector that returns light to the arc tube overheating the bulb.
High Pressure Sodium Lamp Turns Off for 1-3 minutes When A Heavy Electrical Load Starts:
Replace the bulb. This commonly indicates an “end of life cycling” cause by poor load distribution and/or undersized wiring for the length of the wiring run. If bulb replacement doesn’t work, wiring upgrades may be needed. Another issue could be with the reflector not properly returning light to the tube arc.
Sodium, Mercury, or Metal Halide Lamp Alternates On-Off or Goes Out Before Warmup Is Finished
Replace the bulb.
There is a bulb to ballast mismatch and the bulb is the wrong type. Both wattage on the ballast and bulb must match. Slightly different wattages can be acceptable in some cases, such as sodium bulbs of a mercury retrofit type. These bulbs has a nominal wattage that is below that of compatible mercury bulbs.
Matching wattage does not guarantee proper functioning. The 150 watt sodium comes in three different types: S55 or 55 volt nominal arc voltage; S56 or 100v nominal arc voltage; and a mercury retrofit. 1000 watt mercury is sold in H34 and H36 that are not compatible with each other. There are two 1,000 watt mercury bulbs; H34 won’t work properly in a metal halide ballast but H36 will. Some specialty metal halide bulbs and high pressure sodium bulbs, such as “white SON,” are not interchangeable with their more common types that have the same wattage and require different ballasts.
In less common cases, a metal halide bulb placed in a mercury ballast may start fine but then go out during warmup due to some characteristics of the warming up process of a metal halide lamp. Metal halides sometimes do not start and may not reliably work with mercury ballasts.
Mercury bulbs work with metal halide ballasts of the same wattage if the wattage is 175 to 400 watts. This also works for 50-100 watts, but only if they are pulse start metal halide ballasts. Applying power using a bad bulb or one that was just turned off may damage the bulb. This may even be a fire hazard and is not recommended.
Please be aware that mercury and metal halide bulbs will typically be overpowered with pulse start sodium ballasts for 100 volt bulbs. Mercury and metal halide bulbs typically go out before full warmup when powered by pulse start sodium ballasts marked for 55 volt bulbs as most sodiums are 35 to 100 watts.
The burning position restrictions of the bulb are being violated.
A photocell, if it is exists, is catching the light and turning off the bulbs.
Mercury Retrofit Sodium Bulb Has Unreliable Brightness and Gets Brighter with Age:
Mercury retrofit sodium bulbs may not be suitable for some examples of mercury fixtures nor metal halide bulb fixtures. Some are only suitable when a ballast has a “high leakage reactance” autotransformer having the proper open circuit output voltage. In the case of a plain choke or inductor “reactor” ballast where power factor is either connected or not, voltage is usually 230-280 volts with the proper line voltage. Check the instructions that came with the bulb packaging.
Leading, lead-peaked, “CWA”, as well as metal halide ballasts usually do not handle the variations of retrofit bulb characteristics. These change as the bulb ages. The exception being a bulb that is rated for every mercury and metal halide ballast with the proper setting. The property setting is slightly higher than the sodium bulb’s normal wattage. New bulbs may be underpowered while older bulbs may be overpowered.
Metal Halide Bulbs Vary in Color As They Age
This is normal. Radical changes, like a noticeable reduction of the light output, may indicate that the bulb is at or near end of functioning. It is recommended to remove a HID bulb that rapidly changes in characteristics.
Bulb is Flickering:
If the bulb has not flickered before this usually indicates end of life of the bulb, especially if the bulb has been used a lot. Replace the bulb.
High Pressure Sodium Bulb Short Life:
Even with the right wattage the bulb could still be wrong for the ballast. A 150 watt bulb sells in different types. A “white SON” bulb is not interchangeable with other bulbs, including the standard-compatibility improved color type. Some retrofit bulbs have restrictions for metal halide ballasts and mercury ballasts.
Replacement Bulb is Dim or Fails to Warm Up:
Another example of bulb to ballast incompatibility. For example, a H34 1000 watt mercury bulb is used on a H36 ballast or a S55 150 watt sodium bulb is mounted on an S56 ballast. Check wattage, and codes on the ballast and bulb when replacing an old bulb.
Bulb explosions are extremely rare. Explosions are typically caused by three reasons: the bulb being overpowered by a bulb and ballast mismatch: an incorrectly wired ballast: or excessive line voltage. Less likely but still possible is the bulb is operated past its life expectancy. Mercury and metal halide bulbs especially should be replaced after exceeding life expectancy of running time.
Proper enclosed type fixtures are the best designs for containging exploding bulbs. Metal halide bulbs that are not of the protected type are best used in enclosed fixtures since they have a higher chance of explosion.
Replace or discontinue use of any HID bulb should it begin operating erratically, has a major color change, or has a loss of light output that develops in less than a couple weeks. Replace any bulbs that have an unusual bulge or “bubbling” of the arc tube.
High pressure sodiums have less risk of exploding. Sodium arc tube ruptures typically do not cause breakage of the outer bulb.
It is recommended not to run halide and mercury lamps 24/7, 365 days a year. Turning off metal and mercury bulbs once every couple of weeks can give warning of bigger issues or impending failure as they may fail to restart or produce erratic problems listed above that indicate the new for a replacement bulb.