You’ve likely walked into a light bulb aisle at a store, and been completely overwhelmed with all of the choices. Big box and grocery stores don’t always have experts available, that really know lighting, to help you sort through it all. In this article, I’m going to help you understand what to look for.
Selecting the right bulb is going to include knowing not just how bright a light bulb can be, but which type you should be twisting into your lamp or ceiling fixture. You also need to know about the different bases, shapes and sizes so you purchase a bulb that fits in your current fixture.
So, as seamless as the transition from day to night, let’s illuminate the exciting world of light bulbs. We’re going to explore the different types, each with its own set of pros and cons, energy uses, and best use scenarios.
Exploring the Spectrum
Incandescent Bulbs
This had been, until recently, the most common type of bulb. Because of it’s inefficiency, which we discussed earlier, they are being phased out in favor of bulbs that use less energy. As of July 2023, the new federal standard requires a minimum efficacy (how efficiently does it use the energy it consumes) of 45 lumens per watt, effectively banning incandescents and some compact fluorescents, and removing them from the shelves at your favorite store. You can, however, still find them online, and you may have some tucked away yet in a storage closet.
So then what? If the bulb you that you’ve always bought is no longer available, how do you know what to replace it with? Start by looking at the bulb you have, is there a legible marking on it that looks like code? Great! Knowing what you have is half the battle. If it’s evaporated, look for a label in your fixture to tell you the size and maximum wattage that fixture can take.
You’ve found the code, now what does it mean?
Sizing Things Up, Bulb Sizes and Bases
When you’re getting ready to replace a light bulb, size and base compatibility are as crucial as the bulb type. A common misconception is that all light bulbs will fit any fixture, but that’s far from the truth.
You’ll encounter a range of bulb sizes, each designated for specific fixtures and purposes. For instance, smaller bulbs are generally used for desk lamps and appliances, while larger ones fit better in ceiling fixtures. Not paying attention to the size can lead to ineffective lighting, or worse, damage to your fixtures or a fire hazard. Therefore, it’s essential to know the size and wattage indicated on your current bulb or fixture before heading to the store.
The common lamp above is an ‘A’ bulb, called such because it distributes light in all directions. The size is measured at it’s widest point, in 1/8s of an inch. In this case, 19/8s. If this is a 100w bulb, you would see 100WA19 as the code for this bulb. The base also needs to be considered, the standard being an E26, or medium base. Over it’s life in use that code often evaporates and become illegible by the time you need to replace it. Look for a label in the fixture itself to find what the maximum wattage the fixture is rated for.
An additional component is the voltage the bulb operates at. Common voltages are 12v, 24, 120v, and 130v. The 120v and 130v are interchangeable, and the 130v bulbs tend to be sturdier and last longer. The 12v and 24v cannot be interchanged, they are part of a low voltage system often found in smaller accent lights, track lights, landscape lights, undercabinet or soffit lights, and sometimes RV and boat lights, and have a transformer as part of the system to drop the incoming power to the system from 120v, normal household voltage, to the 12v low voltage. You’ll see the voltage as part of the code, such as our 100WA19 120v or a 40WMR16 12V. If you’re replacing a low voltage bulb, make sure you’ve matched up the voltage for your system. The transformer can tell you the voltage if you’re unsure.
Moving on to bulb bases, they’re the part of the bulb that connects to the power source in your fixture. A mismatch here can mean your light won’t work at all. The most common types are screw bases, which are the standard in most households, and pin bases, typically found in more specialized lighting like track, accent, or certain kinds of recessed lights. The chart below shows you the various types.
To avoid any mishaps, always compare the base of your existing bulb with the new one. Just take the old bulb with you when you shop, or snap a picture to ensure you’re getting the right match. Additionally, if you’re upgrading to a different bulb type — say, from incandescent to LED — verify base and switch compatibility as they may differ.
Understanding the type of base needed for your fixtures is easy once you get the hang of the naming system. For example, an ‘E’ before a number signifies an Edison screw base, and the number stands for the base diameter in millimeters. Similarly, ‘GU’ indicates a type of bi-pin base, often used in downlights.
Now that you have the highlights of where we’re starting from and how bulbs are labeled, let’s look at the different available options.
Halogen
A common replacement for the incandescent bulb is a halogen version. Halogen bulbs are essentially an enhanced version of the traditional incandescent. They’re filled with a halogen gas that allows them to burn hotter and brighter. They use about 20-30% less energy and are often praised for their crisp, white light. As a result, they’re more energy-efficient than regular incandescents, but not as much as CFLs or LEDs. Additionally, you don’t want to touch the glass with your bare fingers, the oil from your skin will deposit on the glass of the ‘T’ Series or Specialty bulbs above, causing that spot on the glass to burn hotter, decreasing the life of the bulb. It can lead to a “non-passive end of life”, or explosion, when that part of the glass weakens and explodes when the electricity hits the filament inside.
The packaging of the halogen ‘A’ bulbs on the shelf do a good job of stating what incandescent ‘A’ bulb it’s replacing. For example, a 45WA19 halogen is generally the replacement for a 60WA19. But, because they don’t meet the 45 lumens per watt minimum they are rapidly disappearing from store shelves as well.
PROS: relatively inexpensive, easy to dim, typical sizes and shapes we’re accustomed to, good light output, uses less energy than traditional incandescents. Sharp, crisp whiter light.
CONS: Not as efficient as CFLs or LEDs, can lead to non-passive end of light, burns super hot
Compact Fluorescents (CFLs)
Then, we have Compact Fluorescent Lamps, commonly known as CFLs. These are the curlicue bulbs you’ve seen around. They’re more energy-efficient than incandescent bulbs and have a moderate lifespan. CFLs work by driving an electric current through a tube containing argon and a small amount of mercury vapor. The bulbs generally meet the minimum efficiency standard, but some states are moving to ban these as well because of the mercury. In older generations of this bulb they can be slow to warm up to maximum brightness, they’re unattractive, and often sensitive to excessive heat if you put them in a sealed up fixture, and sensitive to fluctuations in the energy supplied to it . Some compact fluorescents can look like an incandescents, but if you look closely through the glass you will see the curlicue inside.
PROS: Use less energy than halogens, variety of color temperatures to choose from, long life
CONS: Can be slow to warm up, visually unappealing, light quality is questionable, sensitive to heat build up and energy supply fluctuations. Critical to match the bulb to dimmer for dimming.
So what’s left?
LED Bulbs
LED bulbs shine bright when it comes to energy efficiency. They use up to 90% less energy than incandescent bulbs and could save you a pretty penny on your energy bill in the long run. Also, in theory they last an incredibly long time – we’re talking years. On the downside, they can be more expensive upfront, but if you’re thinking long-term, they pay off. Recently I haven’t been impressed with the quality of bulbs on the shelf from brands never heard of before. If you can buy from an electrical supply house or lighting showroom, they can guide you to brands with better reputations for quality.
PROS: Super energy efficient, variety of color temperatures. Some have the ability to change the color temperature without changing the bulb, and others have the full rainbow of colors within the same bulb to chose from.
CONS: Sensitive to heat build up and energy supply fluctuations. Critical to match the bulb to dimmer for dimming
In our last chat, we talked about the different light sources and how to measure their output. Remember lumens and wattage? Here’s the chart again that references the general equivalences of the different bulb types we just discussed:
Bright Decisions
Now that you’ve figured out the right bulb type to replace what you’ve got, you have a few more decisions to make. Here are some questions to ask yourself:
In my fixture, can I see the bulb? Either through lack of a cover or the cover, or shade, is clear? Choose a clear bulb, either incandescent, halogen or LED. CFLs look terrible in these situations.
Is my fixture on a dimmer? If yes, the easiest solution is an incandescent or halogen bulb. If those aren’t available or you’d like to use LED with a dimmer, make sure the LED bulb is dimmable and your dimmer is rated for LEDs. My personal preference is the incandescent or halogen solution for cost, simplicity, and a nice, smooth dim. Dimming itself is a topic that deserves, and will get, a dedicated conversation in a later article.
What type of fixture am I’m putting this bulb into? A table lamp is going to need a bulb that puts off less heat so as to not burn a delicate lamp shade. Sealed fixtures, like flush to the ceiling fixtures, retain heat and will deteriorate the lifespan of a bulb that isn’t rated for sealed fixtures. Is it a downlight? Some downlights need a longer “neck” on the bulb to fit properly, and pay close attention to the diameter of the bulb and the downlight hole itself. General lighting in relaxing areas is fine at a color temperature in the high 2000s. Go higher in working areas, mid-3000s will do the job.
Is the fixture directional like a spot light or downlight? A BR bulb is great for general lighting from a track or downlight. A directional bulb, like a PAR or MR bulb, is great over work areas like your kitchen sink or counter and will give you bright punch of light over your work area.. Select a cooler kelvin color temperature, in the mid to high 3000s, with a 90+ CRI .
Is the fixture for general lighting or a specific function? What is that function? if it’s general lighting where you spend time relaxing, go for a bulb that has light going in all directions, like an ‘A’ bulb, and in a warmer color. If it’s in your laundry room, clothes closet or craft room, you want to be able to match colors and identify stains, so go for a kelvin temperature closer to 5000, and the highest CRI you can find.
In summary, every bulb type has its strengths and weaknesses. It’s about balancing immediate costs with long-term savings, and considering the environmental implications of your lighting choices. Your decision might swing towards energy efficiency or maybe the ambiance a certain bulb creates for a specific room matters more to you.
While this article touches on the most common questions, shoot me a message if you’ve got a question not answered here!