Light Bulb Guide
by Victor Bryan
When buying a lighting fixture, you must ensure that the light bulb that the fixture utilizes can meet your lighting demands. So once you know what kind of light you need, you are free to choose the fixture that looks appealing to your individual tastes. The fixture look and style is important to your individual aesthetics but the light fixture must first and foremost provide light output that meets your requirements. For example, you want to add some lighting to your backyard garden to light up some tree, bushes or some other object. You’ll need some kind of spot or wide spot type light bulb for your application but you are able to choose different fixtures for that goal. Raw copper, heavy duty brass, composite or powder coated aluminum; bullet style, open face or traditional spot light fixture type, ground or stake mounted; etc.
For example: all the fixtures pictured below all run on MR16 JC Bi-Pin type light bulbs.
Completely different applications, all with the same light bulb. So without further ado, this guide to light bulbs will show the differences among the most popular light bulbs used for lighting fixtures:
JC Bi-Pin 
One of the more versatile light bulbs on the market, the JC Bi-Pin type light bulb comes in both omni-directional or directional, halogen, xelogen or LED, 12V or 120V, clear or frosted. Commonly found in step, deck and pathway lights, these light bulbs are incredibly compact yet highly powerful which makes them perfect for compact or flush fixtures. They are used for flood lighting, accenting lighting, or general small area illumination. Power comes into the bulb via the two pins at the bottom or back of the light bulb, thus the name.
MR Series
Moving on to the MR series of light bulbs, it comes in 3 different sizes, MR8, MR11 and MR16. These light bulbs are based on the JC Bi-Pin design (two pins at the bottom of the light bulb) and are directed light bulbs (generate light output in a single direction). Commonly found in spot lights, in ground lights or landscape lights, these light bulbs are used primarily for spot light or task lighting purposes though some are able to fulfill the role of flood lighting with the appropriate beam spread. These bulbs are mostly 12V but MR16 can support 120V power. MR11s and MR8s only come in the low voltage (12v) variety as they are much smaller and cannot the same power load as an MR16 can. MR11 and MR8 are used almost exclusively for spotlighting but they can be used for accenting light purposes as well.
PAR Series
Moving onto 120V PAR type light bulbs, this is where things get a little tricky. PAR20, PAR30, PAR38 are medium base socket type light bulbs (like A bulbs) while the PAR36 don’t fit into any socket in the traditional sense. You can find PAR20, PAR30 and PAR38 light bulbs in recessed fixtures, in ground lighting, gooseneck barn and sign lights, underwater lighting fixtures and many more. A highly versatile series of light bulbs and they come in traditional 120v options, as well as LED and they are outdoor rated.
PAR36
PAR36 is the exception in the PAR series as it is found more commonly found in 12V. PAR36 light bulbs have two small contacts on the back of the light bulb that attach to spade connectors for power. The advantages of not being forced into a socket means that you have greater control over the angle of the light output (shown below). Both available in halogen or LED for additional power savings. Like the rest of the PAR series, this light bulb is outdoor rated.
Reflector
Reflector light bulbs are very similar to the PAR series light bulbs as they are directional, medium base light bulbs; however, they have the appearance of a frosted light bulb. Similar to the PAR series, they have different sizes, R20, R30 and R40. Found in 120V incandescent, they are used for general illumination for track lighting, down lighting and recessed lighting. They are also not rated for outdoor usage like PAR light bulbs are. The coating helps direct excess light from a fixture’s reflector down in the same direction as the rest of the light.
"A" Bulb
A bulbs are the stereotypical light bulbs that pop up all over the place. They are medium base, rounded light bulbs that are found in table lamps, ceiling lighting fixtures, wall sconces, chandeliers, and other interior fixtures. They specialize in providing even light distribution over a large area which is great for general lighting or wall washing. Commonly, A bulbs are used for 120v lighting purposes as they must produce a higher light output to light up an area (opposed to lighting up a specific spot) however, they are available in low voltage as well for mood lighting.
Bayonet
Last but not least, bayonet type light bulbs, which are used for certain types of spotlights, step lights or deck lights. The light bulbs are Omni-directional, meaning that light output goes in 360° from the socket. Tied with a polished mirror reflector, this means for the step lights make the most of the light output from a relatively small bulb. Bayonet bulbs come in both 12V and 120V, as well as single and double contact versions. Depending on your application, the most popular bayonet light bulbs are either 12V LED bayonet light bulbs or 120V double contact bayonet bulbs.
Beam Spread
Now that we’ve gone through the different types of light bulbs, let’s discuss the different types of beam spread options. Certain light bulbs (MR16, PAR series, JC Bi-Pin) have different beam spread options that provide a little more flexibility with your bulb selection. The different types of bulb spreads are as follows:
Spot-
Used for spot/task lighting, this beam spread excels on single target lighting
Wide Spot-
Used for spot/task lighting, used for similar purposes as the spot but a looser focus
Narrow Flood-
Used for accenting/under lighting/wall washing, used for applications where wider lighting is required than a spotlight
Flood-
Used for accenting/up lighting/wall washing, used for applications where wider lighting is required than a spotlight and wider than a narrow flood
Wide Flood-
Used for general lighting/up lighting/wall washing, used for soft lighting applications where you want only general highlights on your objects or general lighting for large areas
