Why Do Light Bulbs Burn Out?

If your light bulbs keep burning out then several things might be at the root of the problem. Whatever the case, you’ll likely want to fix the issue quickly as if your light bulbs burn out quickly that can be not only annoying but costly too.

Types of light bulbs and their average lifespan

But first, let’s take a quick look at the three main types of light bulbs and the average lifetime of each:

Incandescent light bulbs

Even to this day, this type of light bulbs is very much synonymous with the concept of a light bulb. They do pale in comparison to some of their modern-day alternatives in terms of lifespan, however, as the average incandescent light bulb can last for only ~900 hours or ~4 months assuming you’re using it for 8 hours per day.

Fluorescent (CFL) light bulbs

A much more long-lasting alternative to incandescent bulbs are the fluorescent CFL light bulbs. Their average lifespan is often said to be around 8,000 and 10,000 hours, although most users find them to last only ~3,000-4,000 hours. The discrepancy here is often found in some of the reasons light bulbs burn out sooner than expected we’ll list below.

LED light bulbs

The heavyweight champion of long-lasting and cost-efficient light, LED lightbulbs far outclass the previous two options and can last for as much as 25,000 or even 30,000 hours if used properly. Even if they are misused, however, they often last for “ at least” ~10,000 hours.

Why do my light bulbs burn out quicker than expected?

So, without wasting any more time, here are the 10 main reasons why your light bulbs might be burning out quicker than expected.

The voltage is too high for the bulb

If the supply of voltage coming into the bulb is too high for it to handle, you can very much expect it to burn brighter and faster than expected. To avoid this simply look at the voltage the light bulb is supposed to work with and use a multimeter or a voltage tester to check the socket’s voltage.

The bulb is too strong for the fixture

An alternative problem might be that the bulb’s wattage is just too strong for the light fixture. This is uncommon for LED and CFL bulbs which are usually low wattage but it does happen with incandescent bulbs. To check for that just open the light fixture’s cover or globe and look for its wattage rating – it should be inscribed somewhere on the fixture. Compare that with the wattage of the bulb.

The connection is loose

Another thing to check for is whether the bulb is connected to the fixture properly. If it’s a little lose it may flicker on and off which will cause it to expire quicker, not to mention that it’s just not good for lighting. To fix this, just turn off the power and check the bulb socket – the wires need to be securely and firmly attached to the screw terminals.

The dimmer switch is wrong for the light bulb

If you have an older model dimmer switch it’s possible that it’s designed to work with standard incandescent bulbs only and isn’t suitable for CFL or LED light bulbs. This can cause it to damage the circuitry at the bottom of the bulb over time and cause it to burn out too quickly.

The socket tab of the bulb is depressed

If you look at the bottom of your light bulb, there’s going to be a small metal tab there – that’s the “hot” connection between the bulb and the socket or the “socket tab”. If it’s pushed too far down (i.e. it’s depressed) it might not be making contact properly, thus causing the bulb to not work well and expire sooner.

There’s too much fixture vibration around the light bulb

This may sound too implausible but it’s actually a common problem – if there are too many or too strong vibrations around the lighting fixture, these can cause the filaments inside the bulb to jiggle and shorten its life. Something like a ceiling fan or a continuous repair work upstairs can easily cause this problem.

The insulation of your recessed light is faulty

A common problem for recessed lights is that their insulation is sometimes faulty. Not all recessed lights have such “attic insulation” but when they do, it must be placed well in order to avoid overheating.

The light bulb has been “toyed with” too much

The lifespan of light bulbs may be measured in “hours of continuous work” but what actually shortens their life much more than just running is if you constantly switch them off an back on again. If you’re wondering why the bulbs in your child’s room go off much more often than bulbs elsewhere, for example, it’s often because children love playing with the lights.

There’s been a short circuit

In this case, it’s not the bulb that’s burnt out but your home’s wiring. A short circuit can be caused by a whole lot of other problems that we won’t go over here, but to identify that as the problem simply check if other light fixtures and appliances are also affected.

It’s just the wrong type of bulb

Last but definitely worth a mention, it could be that you’re using the wrong type of bulb for your system. As we alluded to in point 4, some systems are not designed for certain types of bulbs and having an old dimmer switch is just one example of that. Make sure that you know how your lighting fixture works and pick a light bulb that’s right for its components, voltage, and wattage, as well as for your needs and preferences.


Blogger, editor, developer who loves green living. Interested in photovoltaics and solar lighting. Reviewing solar products since 2013.

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