Do Fluorescent Bulbs Get Hot? Everything You Need To Know!

When you decide to get bulbs for your home, fluorescent bulbs are one of the options you may be thinking of trying. One thing to consider before purchasing any lightbulbs is safety. Some lightbulbs have a greater chance to cause a fire than others, so, do fluorescent bulbs get hot, and how hot do they get?

Fluorescent light bulbs do get hot because they are not 100% efficient and so they can’t convert all the electrical energy into light energy. Some of the electrical energy is lost in the form of heat. However, fluorescent bulbs generally release less heat as compared to incandescent light bulbs.

Further in this guide, I will be giving you a clear picture of why fluorescent light bulbs get hot, how much they get hot, and some related questions. So to get complete information about everything make sure you stick around till the end and let’s begin!

Do Fluorescent Bulbs Get Hot Everything You Need To Know!

Why Do Fluorescent Bulbs Get Hot?

To understand why fluorescent light bulbs, and basically why most light bulbs produce heat, we need to understand the Law of Conservation of Energy.

So as per this law, energy can neither be created nor can it be destroyed. It can only be converted from one form to another form.

Now, in general, with any kind of light bulb you take, there is going to be some kind of resistance in it. A Light bulb in general does behave like a resistor.

And in simple words, resistors are the components that resist the electron flow through them. 

When electricity flows through the light bulbs some part of the energy is used to produce the light depending on how efficient the light bulb is. 

The rest of the energy is converted into heat because of the ‘resistance’ that light bulbs offer.

So in short here’s what happens in practically all light bulbs:

Electrical Energy = (Light Energy + Heat)

Following this principle, let’s say you turn on a 100 watt light bulb. Then depending on how efficient the bulb is, a part of the total of 100-watt electrical energy will be converted to light energy and another part as heat.

Now, if you have ever wondered whether or not light can exist without heat, I would recommend you to check out my blog post where I have explained about can there be light without heat in detail.

You will find that some light bulbs are more efficient in producing light than others. 

Remember that if a bulb is 100% efficient then it would convert all the electricity into light and produce no heat.

Incandescent Light Bulbs:Fluorescent Light Bulbs:LED Light Bulbs:
Only 10% of the energy used by an incandescent bulb is converted to light.About 85% of the energy used by a fluorescent bulb is converted to light.They convert about 90% of electricity to light.

Factors that decide how much heat will be produced by a particular bulb are:

  • Type of Bulb
  • Wattage
  • Shape of the Bulb
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Now you might be thinking about why and how the shape of the bulb can impact the heat produced. Well, though it is a secondary factor, the shape of the bulb can also determine the heat produced.

For instance, if the shape of the bulb is such that all the light and heat is particularly concentrated in a given area then that area will feel hotter as compared to the case where light and heat are diffused to a larger area.

Is It Normal For Fluorescent Light Bulbs To Get Very Hot?

Fluorescent lights produce less heat as compared to incandescent bulbs. However, if you notice that your fluorescent bulbs are very hot suddenly then there might be some issue.

Let’s see in detail what causes a fluorescent bulb to get overheated!

What Causes Fluorescent Lights To Overheat?

In fluorescent lights, ballast, a special device is used to start the electric current creating light within each bulb.

The ballast interacts with the lighting mechanism to control, regulate and stabilize the light output of the lamp. All fluorescent lights require a ballast in order to operate properly. 

Now over time, this ballast wears out and starts to show signs of wear such as overheating. Also, there are other reasons that can lead the ballast to get overheated.

#1. Having Poor And Damaged Starters

Although in many newer fluorescent lightings, the rapid starting mechanisms are present. However, there are some older models of fluorescent lighting that separate the starters that help in lighting up the bulb when the switch is flipped.

Now the problem is that these starters can get stuck closed and fail to open when electricity is sent to the ballast. As a result, the ballast gets overheated.

#2. Choosing Wrong Bulbs

The ballast in fluorescent lighting is designed such that it can send a specific amount of voltage through the bulb. However, when we choose the wrong size or voltage bulb the ballast will often get overheated and thus even cause the light to shut off.

Actually, the bulb and fixture both should match the frequency otherwise ballast gets overworked and overheated. 

Slow and obvious flickering or a loud whine are some signs of incompatible bulbs.

#3. Wiring Issues

If because for any reason, extra voltage runs through the fluorescent bub ballast then it can cause overheating. And one of the most common causes of this problem is the wrong wiring done during the construction or installation of the fixture.

Now if a fixture keeps on overheating the ballast no matter whatever you do to stop it then most probably it is because of some issue in the wiring.

And in such a case, you will have to rewire the fixture or the ballast will continue to overheat and even you might have to replace it.

#4. Power Surge

The ballast used in a fluorescent light bulb is generally sensitive to spikes in the power supply. Whenever a lightning strike or any issue in the power line occurs, it causes a sudden spike in the amount of electricity that is sent to our houses and it can cause damage to all of our appliances.

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So in the case of fluorescent bulbs, even a short surge can heat up the ballast so much that it can even cause it to break.

However, if you install surge-control devices between your lighting fixture and its connection to the electrical line then it can help you prevent this issue.

How Hot Do Fluorescent Bulbs Get?

In general, the fluorescent bulb will mostly stay cooler because they have good efficiency at least as compared to incandescence bulbs.

The Proprietary test highlights 100W incandescent lights burning at 335.4 F, CFL lights burning at 179.2 F, and LED bulbs burning at 87.2 F.

Just to let you know, CFL stands for Compact Fluorescent Lamp and it is nothing but a fluorescent lamp designed to replace an incandescent light bulb.

As per, in a 100 watt incandescent light bulb, the filament temperature can be up to approximately 4,600 degrees Fahrenheit. Although the surface temperatures of the incandescent bulbs vary from 150 to more than 250 degrees.

On the other hand, Compact Fluorescent light bulbs can have a surface temperature of 100 degrees Fahrenheit.

Do Fluorescent Bulbs Get Hotter Than Incandescent Bulbs?

No, the fluorescent light bulbs get less hot as compared to the incandescent light bulbs. The reason why incandescent bulbs produce more heat as compared to fluorescent bulbs is mainly because of how the light is created inside the bulb.

The normal light bulbs (incandescent light bulbs) have a very thin tungsten filament that is placed inside a glass sphere. You can find these light bulbs in sizes such as 60-watt, 75-watt, 100-watt, etc.

The main principle behind how these light bulbs work is pretty simple. Through the filament of the bulb, electricity runs and since the filaments of these bulbs are thin they offer good resistance to electricity. As a result of this resistance, the electrical energy is turned into heat.

Now the heat is so much that it makes the filament white-hot and this white-hot part is what we notice as light.

The filament basically glows because of the heat. (Incandescence means emitting light as a result of being heated)

Now the issue that comes with the incandescent light bulbs is that this heat generated actually wastes a lot of electricity. The main purpose of light bulbs is to produce light and not heat. 

Hence, all the energy that is used to produce heat is totally a waste for us, right? And because of this reason, incandescent light bulbs become quite inefficient.

On the other hand, a fluorescent bulb works in a different way to produce light. Let’s consider a fluorescent tube to understand how it works in a simplified way.

So in a fluorescent tube, there are electrodes at both ends. And inside the tube a gas containing mercury and argon vapor is present.

When the electrical power is turned on, the electrons flow through the gas from one electrode to another electrode. These electrons actually bump into and excite the mercury atoms.

When the mercury atoms move from the excited state back to the unexcited state, ultraviolet photons are released.

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The photons then hit the phosphor coating that is present inside of the fluorescent tube and this phosphor creates the visible light.

The word fluorescence actually means the visible or invisible radiation emitted by any substance because of the incident radiation of a shorter wavelength such as X-rays or ultraviolet rays.

I would also recommend you to have a look at my blog post on do light bulbs emit UV rays in case you are interested to know more about it.

In the case of fluorescent light bulbs, the phosphorus fluoresces to produce light.

A fluorescent bulb also produces heat but it is less and so it is much more efficient. As per HowStuffWorks, a fluorescent bulb can produce between 50 and 100 lumens per watt.

This makes fluorescent bulbs to be around 4-6 times more efficient than incandescent light bulbs. So for example, if you buy a 15-watt fluorescent bulb then it will produce almost the same amount of energy as you would find a 60-watt incandescent bulb.

Do Fluorescent Bulbs Get Hotter Than Led?

Yes, fluorescent bulbs can get hotter as compared to LEDs since fluorescent bulbs are less efficient than LED bulbs. The fluorescent bulbs can’t convert the electrical energy into light energy as an LED bulb would. So the rest is converted into heat and dissipated.

In a LED bulb there are a number of different light-emitting diodes. Now each of these diodes produces light from a semiconductor chip with a negative and positive charged terminal.

When the electrons move from the negative to the positive, the get collided with the positively charged particles (holes) and fall from a higher energy state to a lower energy state. The drop is what releases energy in the form of light.

LEDs are quite efficient and so they require less energy to produce the same amount of light as compared to incandescent or fluorescent bulbs. They generate less heat in general as compared to other bulbs.

But is there any risk of fire hazard associated with LED Lights? Well, to know more about it I highly encourage you to check out my detailed blog post about do LED lights get hot enough to start a fire.


In short, fluorescent bulbs do get hot just because like any electrical appliance, fluorescent bulbs will also offer at least some kind of resistance to the electricity and thus generate heat along with light.

But in general, the fluorescent bulbs get less hot than the incandescent bulbs but more as compared to the LEDs.

So in terms of which bulb produces the least heat, LED is the clear winner. They are very much efficient in utilizing electrical energy as compared to both incandescent and fluorescent bulbs. Hope this helps!

Now, have you ever thought of removing a bulb and keeping the socket open? Then I highly recommend you to check out my blog post on whether or not it is safe to leave a light bulb socket partially unscrewed or empty.

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