Why Do Light Bulbs Burn Out?

3 types of light bulbs: Incandescent, CFL, and LED.Light bulbs burn out for a variety of reasons, but the most common cause of a burnt out light bulb is simply the passage of time.

All light bulbs have a rated lifespan, which is the amount of time they are expected to last under normal operating conditions.

Once a light bulb reaches its rated lifespan, it will begin to degrade and eventually, you’ll end up with a burnt out light bulb.

How Long Do Light Bulbs Last?

The lifespan of a light bulb can vary greatly depending on the type of bulb and how it is used.

Incandescent bulbs are notorious for consuming the most energy and are generally the culprit when you have a burnt out light bulb.

Incandescent lights also have the shortest lifespan, while LEDs are hailed as the ruling industry standard.

Here are the average run times of the four most common light bulbs.

It’s worth noting that these averages are by no means set in stone. This Lighting Basics article gives a broader overview.

How long do CFL bulbs last? Incandescent or CFL bulbs that are frequently turned on and off, such as in a hallway or bathroom, will not last long as one that is kept on for longer periods, like in an office.

Do LED lights burn out? LED bulbs are unaffected by how often they are turned on and off, but a faulty circuit or fluctuating temperature environment can shorten their lifespan.

See our post on LED vs Incandescent Lights – Myths & Truths.

There are several factors that can affect the lifespan of a light bulb, including:

  • The type of bulb (incandescent, LED, CFL, Halogen)
  • The quality of the bulb
  • The way in which light bulbs are used (or misused)

Most Common Type of Burnt Out Light Bulb

Incandescent Light Bulb Burned Out – These have a shorter lifespan because they produce light by heating a filament, which can wear out sooner than an LED bulb.

LED Light Bulb Burned Out – LED bulbs, on the other hand, have a longer lifespan because they use a different method of producing light. Even though they produce far less heat and are a lot more efficient, eventually, they to will burn out.

Quality of the Burnt Out Light Bulb

Another factor that can affect the lifespan of a light bulb is the quality of the bulb itself.

Cheap, low-quality bulbs are more likely to burn out prematurely, while higher-quality bulbs are more durable and have a longer lifespan.

How Light Bulbs Are Used Affect Their Lifespan

The way in which a light bulb is used can also affect its lifespan.

If a light bulb is turned on and off frequently, it will have a shorter lifespan than a light bulb that is left on continuously. This is especially true of incandescent light bulbs that use a filament.

The filament will cool down and contract when the bulb is turned off. It will also expand rapidly when it is turned back on. This repeated expansion and contraction can cause the filament to weaken over time, leading to a shortened lifespan.

Other Causes of a Burnt Out Light Bulb

There are also other factors that can cause a light bulb to burn out prematurely, such as:

  • Poor Connections
  • Circuit Issues & Voltage Fluctuations
  • High Temperatures & Lights Overheating
  • Physical Damage or Excess Vibrations
  • Incompatible Dimmer Switches & Lights

If a light bulb is subjected to voltage fluctuations or high temperatures, it can cause the filament to weaken and eventually burn out.

Physical damage to an incandescent or LED light, such as a bulb that has been dropped or bumped, can also cause it to burn out prematurely.

Poor Connection

Yes, we know you know how to screw in a light bulb, but you’d be surprised how often something so simple can be to blame.

A bulb that is screwed in too tight can depress the socket tabs. These small metal tabs at the bottom of a light fixture’s socket carry the power to the light bulb.

If they get pushed too far down, it can break the connection of electricity, causing a light bulb to go out even though it still works.

If a light bulb is screwed in too loose, you might start to see the light flickering. A loosely connected light bulb will burn out faster due to the intermittent voltage caused by the improper connection.

Hitting that sweet spot of not too tight but not too loose will extend the lifespan and minimize burnt out light bulbs.

Circuit Issues

If it’s always the same light fixture that’s giving you grief, then loose wiring could be to blame. A loose connection could cause the voltage to vary which would contribute to your light bulbs burning out faster.

If the contacts become corroded, this could also cause the voltage to vary. When the power is intermittent it is like constantly switching the light bulb on and off. You may need to hire an electrician to replace the light fixture.

Pot Lights Overheating

Does it feel like you’re always replacing a burnt out light bulb in your pot lights? Overheating may be to blame for frequent pot light bulb replacement.

Older recessed light fixtures do tend to run hot and if your home’s insulation is too close, the light housing could possibly overheat.

Newer pot lights may include an automatic shut-off feature if it overheats. Without this feature, the bulbs may start to flicker or even prematurely burn out. Not only is this annoying, but it can also be a fire hazard.

You could opt for the newer IC-rated recessed light fixtures to avoid this problem.

Using a bulb with a higher wattage than what’s rated for the fixture can also cause overheating. The higher wattage creates too much heat inside the globe, which will cause the bulb to burn out faster.

Excess Vibration

You might be wondering why on earth your light fixture is vibrating, but we promise earthquakes aren’t to blame.

Fixtures like ceiling fans or automatic garage door lights must deal with a certain degree of vibration inherent to their function. If a ceiling fan becomes loose or imbalanced, that vibration will increase.

Vibration can cause incandescent bulbs to burn out prematurely by breaking the filaments. Lights may also flicker due to a loosened connection.

The easiest way to combat this is by switching to an LED bulb (since they have no filament) for fixtures when vibration is inevitable. There are also specialized rough service bulbs that are designed to handle vibrations better.

Incompatible Dimmer Switches

Set off light switches with slider dimmer switches.Light dimmers are sneaky, and they’ve been known to get the better of people.

For example, putting a non-dimmable bulb in a dimmable fixture can cause the fixture to short-circuit and ruin your brand-new lamp. So be careful and pay close attention to the type of bulbs required for each fixture.

Likewise, if you find you keep getting a burnt out light bulb in a fixture controlled by a dimmer switch, your wall switch may need to be changed if it has the wrong kind of light dimmer.

Older dimmers were designed for incandescent bulbs only. Using a CFL or LED bulb in conjunction with this old dimmer can damage the circuitry in the bottom of the bulb and cause it to burn out faster.

Consider what type of dimmer switch you have, and upgrade to one compatible with CFL and LED bulbs.

How to Extend a Bulb’s Life & Prevent a Burnt Out Light Bulb

Despite the various reasons why light bulbs burn out, there are steps you can take to extend their lifespan and get the most out of your bulbs.

Use High-Quality Bulbs

One of the most effective ways to extend the life of your light bulbs is to use high-quality bulbs that are designed to last longer.

Only Use Light Bulbs for Their Intended Purpose

It is also a good idea to use bulbs that are appropriate for the intended application, as some bulbs are better suited for certain tasks than others.

We throw a lot of mud at the traditional incandescent bulbs, so you might ask yourself, why are incandescent light bulbs bad?

The main reason is their inefficiency. They consume the most energy, generate more heat than light, and don’t last nearly as long as other options on the market.

If you’re using an archaic light bulb (like an incandescent) or a bulb that’s unsuitable for its location, you’ll find yourself changing light bulbs more often than you would like.

LED bulbs are best suited to fixtures that get a lot of action, like motion sensors or bathrooms where they are constantly being turned on and off again.

You could also be using a bulb wattage that’s too large for the light fixture, which can be dangerous! Exceeding the rating of the light fixture creates excessive heat, which can melt the insulation on the fixture wiring and even lead to a fire.

Turn Lights Off When Not in Use

Another way to prevent a premature burnt out light bulb is to turn them off when they are not in use. This can help reduce the number of times the filament is heated and cooled, extending the bulb’s lifespan.

Avoid Temperature & Voltage Fluctuations

Additionally, you can try to avoid exposing your bulbs to high temperatures or voltage fluctuations, as these can cause them to burn out prematurely.

Standard electrical outlets in homes across North America are 120 volts. If you’re worried about the voltage supply to your house, have a licensed electrician complete an electrical safety inspection.


In conclusion, light bulbs burn out for a variety of reasons, including the passage of time, the type of bulb, the quality of the bulb, and the way in which it is used.

To prevent a burnt out light bulb and get the most out of them, it is important to use high-quality bulbs that are appropriate for the intended application, turn them off when they are not in use, and avoid exposing them to high temperatures or voltage fluctuations.

About Premium Electric

Premium Electric services both commercial and residential clients throughout the Greater Vancouver and Fraser Valley area of British Columbia.

Talk to our electricians if you need help with a burnt out light bulb or any of the following:

Our electricians are fully bonded and certified, and no electrical job is too big or too small.

Please call us at 604-308-6195 or contact us online.

You can also reach us by email.

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