Before you starting any recessed can light installation take the time to get to know the basics. I have been an electrical contractor for 8 years and deal with countless recess can light installations. I will be going over the light styles and types as well as basic layout and design information.
How do you know what size is right? The standard light sizes are 3 ", 4", 5 "and 6". My rule is the lower the ceiling the smaller the recessed can. For ceilings less than 8ft I recommend 4 "cans." 4 recess lighting also work well for accent lighting since the light opening is small and less visible. A typical installation would be using a 4 "can light to highlight a piece of art work For ceilings 8ft and over a 5" or 6 "can lights will work great. although they also can be used for accent lighting if desired.
In addition to size recess can lights also come in different voltages. Standard incandescent can lights operate at 120v and use 120v light bulbs. Incandescent cans are the oldest and most reliable as well as the least expensive. Incandescent or 120v bulbs are also cheaper than low voltage bulbs. The other type of recess can is low voltage. Low voltage lights connect to 120V but then use a transformer or ballast to lower the voltage to 12V. Low voltage recess can use less power than incandescent but are more expensive and have higher prices bulbs. In addition to the higher price low voltage cans also have a transformer that needs to be replaced every 4 – 6 years.
A recessed can light trim is the ring and reflector that covers the inside housing of the light. The trim is typically one piece and it installs into the can housing before the lamp. The trims purpose is to reflect or aim light out of the recessed can while covering the metal can housing. Trims come in many different styles that are made for a specific use. Below I have outlined some of the basic types of trims available. Baffle Trim: used in most general light applications. This is standard white ring with a white or black interior. Eyeball trim: Eyeball trims can be adjusted typically 360 degrees and can be aimed at a 30 to 45 degree angle. This is useful when the light needs to be aimed in a specific direction or area. Wall Wash Trim: This is used typically along walls. The trim is similar to a baffle trim but half of the light opening is covered. The half cover directs light in one direction creating a wash effect. Reflector or Alzak Trim: These trims typically have a white trim ring and a metallic gold or silver interior reflector. These reflectors can produce dramatic highlights and the gold trim can warm up the light color. Shower or Vapor Tight Trim: These trims are typically used over showers and baths but can also be used outdoors and in other damp environments. This style trim has a protective cover over the lamp so water can not enter the light and is usually limited to a 40W lamp. Custom Trims: Custom trims are available from some manufactures and many are off 10 or more colors in most standard styles. Custom color trims are typically not a stock item and are usually a non returnable.
Before you install any recessed can lights read this section carefully. Recess can lights come in different housing rating. The standard ratings are IC, non IC and air tight. If your recessed can be installed in a insulated ceiling space you must install an IC rated housing. Non IC rated housing installed next to insulation is a fire hazard and is extremely dangerous. It is my recommendation that IC rated housing should be used in every application to avoid any possible problems.
IC Rated: IC rated recess cans must be installed where insulation will be in direct contact with the housing of the light. The IC rating means that the recess can housing will stay cool enough to touch flammable materials and not be a fire hazard.
Non-IC Rated: Non-IC rated recess cans require that there be no contact with insulation or flammable materials. A non IC rated housing becomes hot during use and has the possibility of igniting flammable material within 3 "of the housing. recess can housing.
Air- Tight Rated: Air Tight rated means that when the recessed light fixture is fully assembled and installed it forms an air tight seal. This seal stops any hot or cold air loss and keeps your home more energy efficient.
When you are selecting a recessed can light be sure to consider the bulb type. The wattage, size, brightness, and cost can vary greatly depending on what style light is selected. Be sure that you read any instructions in the manual to ensure that you are installing the correct bulb wattage and size. If you install the wrong bulb it may burn out quickly, not work at all, or even worse over heat and cause a fire hazard. Below are the most common types of bulbs for recessed lights.
Incandescent: Otherwise known as "A" bulbs, are low-cost and excellent for all types of lighting applications. They are fully dimmable and are readily available for purchase at a large variety of stores. Typical wattages are; 25, 40, 60, 75, 100 and 150.
"R" or "BR" bulbs: Typically cone shaped and has a reflector that helps disperse the light. They come in different light spreads such as; wide flood, narrow flood, and spot light. They are also available in many different sizes. Typical wattages are; 45, 65, 75, 90W.
Halogen: Halogens are similar in size and shape to "R" bulb but produce a brighter and whiter light. They are more expensive that "A" or "R" bulbs but have a slightly longer life expectancy. They come in different light spreads such as; wide flood, narrow flood, and spot light.
Low voltage bulbs: Low voltage light bulbs are the most expensive and have a longer life expectancy than incandescent. They use less energy than the other bulbs but must be used with a light fixture that has a transformer that lowers the 120V to 12V. An example of a low voltage light bulb is a MR-16.
Last but not least I will cover the recess can housings. There are two different styles that are made for a specific type of installation. If you select the wrong housing it may complicate the installation or even make it impossible. Please read the names and description carefully so you are able to understand what housing is right for your installation. New construction housings are attached to the ceiling supports before the ceiling surface is installed. If the area above the ceiling is accessible these fixtures may also be installed from within the attic space. Remodel housings are used on existing ceiling installations and allows most of the installation to be done from below. Remodel cans do not attach to the ceiling frame but instead have clips that secure it to the drywall opening.