Choosing Circular Fluorescent Light Bulbs

circularIt can be difficult replacing a circline CFL. Circular fluorescent light bulbs differ in many ways and sometimes come with manufacture-only specifics. So which one is right for your light fixture, and how can you tell the difference?


Before purchasing¬†circular bulbs, you need to know the diameter of the bulb needed. You can do that by measuring an existing bulb for the fixture, or looking up the manufacturer model number and finding the compatible bulb. Bulbs range from 5″-12″ in diameter.

Wattage and lumens

Wattage is how much power the bulb consumes and lumens is how much light the bulb emits. The lower the wattage and lumen ratings, the less light the bulb will provide. Higher wattage and lumen ratings give off more light.

Manufacture-only specifics

Some light fixtures only allow bulbs from the same manufacturer to be used in it. If a bulb from a different manufacturer is plugged into the light fixture, the bulb will not work.

Color temperature

The brightness of circular fluorescent light bulbs depends on the color temperature. The numbers range from 2700K to 5000K; the higher the number the brighter the bulb. Specifics are:

  • 2700K: This is a warm white color, the type you would expect to see in living rooms and bedroom.
  • 3000-3500K: This bulb is suited for bathrooms, giving off a soft white color.
  • 4100K: For a cool white color, almost florescent white, use a bulb with this temperature.
  • 5000K: You’ll get the brightest color, daylight white – like the color of the sun at noon, from a 5000K temperature circline CFL . This bulb is best suited for when you need the brightest light, like in painting and drawing rooms.
It’s important to keep all of these factors in mind when choosing the right circline CFL. Especially keep in mind manufacture-specifics, and be sure to read the description on either the bulb or the fixture before making a decision.

Are the pin based bulb interchangeable from one manufacturer to another

This is a question that is posed to our customer service quite frequently.
Unfortunately there is no short yes or no answer.

For the most part, if you are matching up the pin-base and the wattage, bulbs should be interchangable regardless of manufacturer.

It’s straightforward with bulbs like four pin, G24q-3 base. If you match that information up exactly, they should be interchangeable.

It’s much harder with 2 C circular bulbs because different manufacturers will align the pins slightly differently.

Some manufacturers don’t publish a “base type”, which makes matching bulbs nearly impossible. It’s very difficult, for example, to match up Lights of America to other brands successfully.

The future of lighting is the GU24 base, which is completely interchangable regardless of manufacturer. A nice thing about this design is that if the fixture takes a 26w bulb, you can use any GU24 bulb with an wattage bulb equal to *or less than* 26w.



Pay attention to Wattage when buying Pin Based Replacement Bulbs

Why? Because the size of the pins on pin base replacement bulbs depends on the wattage of the lamp. Therefore you have the same wattage bulb in order to replace it or it won’t fit. My friend recently purchased a 38W 2D pin lamp to replace the bulb that had burned out in her fixture. The pins didn’t fit. On closer inspection, she noticed that the old bulb said 55W. She went out and bought the 55W bulb and yes the pins fit in correctly! You don’t have this problem with screw in bulbs – they are flexible and you can select from a variety of wattages and shapes to go into the same socket.

So if your pin base bulbs burns out and you have to replace the pin base circular lamp say, make sure you’re replacing it with the same wattage. This is one of the disadvantages of pin based lamps.

There are other CFL bulbs in the market that don’t have this problem. GU24 bulbs offer more flexiblity in that you can replace the bulbs with different watt bulbs. Moreover, they are compact.


Why does this Pin Based Lamp not fit my fixture?

I’ve heard this twice last week. Friends and customers had purchased a pin based bulb and tried to replace their existing burned out bulb.
When they inserted the lamp into the fixture it wouldn’t go in. The fixture seemed the right size and shape but the pins were the wrong size and wouldn’t go in to the socket.

What’s going on they asked me? One had a 2D lamp and they other had a 4 pin quad lamp. Although different styles of bulbs, they were both pin based. The answer for both of them had to do with the lamp being the wrong wattage. Pin Based lamps have one disadvantage: they are wattage dependent. So you have to put a lamp of the same size wattage into the fixture. If you want a different wattage e.g. going from 55W to 38W, you will have to change out the fixture. So in the case of the friend with the 2D Lamp, she needed to put in a 55W 2D bulb not a 38W.

This is an issue you don’t face with GU24 fixtures. It’s easy to swap out a bulb of a different wattage. See last week’s post on the advantages of GU24 base bulbs.