LED recessed cans guide for kitchen ...
A collection of tips/ answers
Since kitchens have higher lighting requirements, I like to use 35 lumen per sq ft as a rule to compute the number of lights. If there are additional sources of light that will be used, the output (lumens not watts) from those sources can be deducted from the total.
1. Cans should be > 24 to 30 inches from the wall (on center). Most countertop spaces have upper cabinets (typically ~ 12" deep) + crown molding. The edge of the can may be spaced ~ 12" away from the edge of the crown molding (if present or cabinet if there is no crown molding) making the average distance between 26 to 30 inches.
2. Assuming the need for a fairly uniformly lit space @ 35 lumens per sq ft, the cans may have to be spaced closer together - between 3 - 4 ft apart (if all general lighting is provided by recessed lights). A fairly regular pattern is preferable to a random layout.
3. The actual layout of cans will be impacted by the location of ceiling joists, HVAC ducting, electrical wiring, plumbing, ceiling height, fire suppression sprinklers and other obstructions above the ceiling.
The Cree LR6 series lamps do not dim as well as the later models (CR6, ...). ELV dimmers probably work better with LR6 than incandescent dimmers since the total load of the lights may not meet the minimum load requirement for the incandescent dimmer.
Dimmers such as the Lutron Diva CL dimmers work well. The max output is 95%.
Some Choices (in order of preference) and notes
Cree CR6 or ECO-575 (Home Depot branded CR6)
ECO4-575 (Home Depot branded Cree CR4 4" recessed light)
The above are only available in 2700k light color.
Cree LR6 series - including the LE6.
The Cree CR6 and LR6 lamps will not fit into 5" housings.
The standard LR6 behaves more like a surface mount than a recessed light as the LED emitters are close to the surface and the recess is shallow. Some may not like the amount of light spillage (standard LR6).
There is a higher output version of the LR6 that has a much deeper recess.
To prevent the Cree lamps from falling out, the 3 prongs have to be fully extended and a slight clockwise twist made when push installing. The slight clockwise twist will ensure that the prongs are fully extended.
The Cree lamps are currently the best available today (2012).
Sylvania RT-6, RT-4. The lights could be easier to install than Cree lamps as they utilize the torsion spring mechanism. However, the lights do not look as pleasant as the Cree lamps.
The Cree and Sylvania lamps do outperform 26W CFLs (and incandescents) in a standard recessed can in terms of light spread and output as the standard bulb in a can solution traps a significant amount of light. The Cree and Sylvania recessed lamp solutions referenced above have all the LED elements facing outwards so that the effective light output is higher.
The CRI (Color Rendition Index) of Cree and Sylvania recessed lamps > 80.
There is no warm up time required for Cree recessed lamps, unlike CFL light bulbs.
Most recessed lighting is used with flat ceilings. Sloped ceilings would require special solutions such as the LE6 or some other form of lighting (i.e. -non recessed lighting).
Some common objections to recessed can lights stem from
1. looks and performance of traditional can lights (standard bulb in a can)
2. swiss cheese effect from too many holes.