Choosing A Light

Choosing the Right Type of Light

There are many good reasons for lighting including worker safety, task manipulation and quality of work, product inspection, security and increased productivity. Each of these reasons may require a different intensity of light (lumens or foot-candles), degree of whiteness, color rendering level and types of lamps and fixtures.

What is the best type of lighting?
The best type of lighting is the one that provides the needed amount and type of light to perform a task or increase productivity at the minimum annual cost (operating and fixed costs).

What is being lit?
The area to be lit may be animal housing, driveways, office space or storage space, each with its own requirements for light levels and light type. Is the area warm or cold, with high ceilings or low, is there constant or occasional activity, does activity involve precision work or is it general lighting? All of these are factors in deciding what type of lamps and fixtures to use.

What is the duration of lighting?
How long lighting is needed depends on the situation. Many times it may only be for short periods of time while a task is being completed, while applications such as Long Day Lighting in barns will require lamps to be operated for up to 18 hours per day. What is the percentage of time there will be work activity or movement in the target area? Do the lights need to be on all of the time or just when there is activity in the target area? If the answer is only when there is activity, the lighting might be controlled with a motion sensor and the use of an incandescent bulb or halogen lamp for the instant-on feature. However, if there is frequent movement causing the lights to be operated more than 30% of the time, you’ll save energy using a high pressure sodium (HPS) lamp or LED lamp and operating it during all hours of darkness. You should assess the needs of each area to determine the required duration of lighting.

What is the amount of light needed?
Different tasks require different levels of lighting. An area that is lit for precision work requires a higher light intensity than security lighting or machinery storage. The chart below lists some examples of the tasks done on a dairy and poultry farm and the recommended lighting level. For recommended lighting levels for other areas and tasks refer to ASABE Standard EP344,  Lighting Systems for Agricultural Facilities, or the Illuminating Engineering Society Handbook.


Task Intensity/Light Level Task Intensity/Light Level
Free stall 15-20 foot-candles General Livestock Housing 10 foot-candles
Tie stall – free alley 20 fc Tie stall – center alley 20-50 fc
Holding area 10-20 fc Milk room 20 fc
Milking Parlor – general lighting 20 fc Milking parlor – operator’s pit 50 fc (at cow’s udder)
Vet/Treatment Area 20 fc Treatment/Surgery Area 100 fc
Manual Wash Sink 100 fc Utility Room 20 fc
Office Area 50 fc (desk top) Machine Storage 10 fc
Farm Shop-general repair area 50 fc Restroom 20 fc
Exterior-security 0.5 – 1 fc Exterior-active areas 3 – 5 fc
Poultry Barns 20 fc Egg Packing and Inspection 100 fc
Inside Incubators 50 fc Loading and Storage Areas 20 fc

What types of lamps are appropriate?
Lighting is quantified by two indexes: Color Rendering Index (CRI) and Correlated Color Temperature Index (CCT). The CCT, which is a measure of the light color, is not as important as the CRI, which is an indication of how humans perceive the colors when lit with a particular lamp compared to natural sunlight. If one needs to differentiate between colors to properly perform a task, then a lamp with a high CRI value is necessary. A CRI value of 80 or higher is required for color matching. For general farm lighting where some color detection is needed, a CRI of 50 or higher would likely be sufficient. In areas were color detection is important, like treatment pens, milking parlors or egg sorting facilities, a CRI of 70 or higher is recommended.

The air temperature will also have an effect on the choice of lamps as some have minimum starting temperatures such as fluorescent lamps. If there is need for instant-on lamps, it will limit the use of high intensity discharge (HID) lamps as they take several minutes to fully illuminate. The compact fluorescent lamps (CFL) and T-8 fluorescent lamps would be limited if the area to be lit gets colder than 32°F or 0°F depending on lamp rating.

What types of fixture are required?
Inside any animal housing or processing facility with high humidity, the fixtures must be water and dust resistant. Plastic, fiberglass or stainless steel housings are preferred because of their resistance to corrosion. Incandescent and compact fluorescent lamps shall be enclosed in sealed globes and linear fluorescent lamps shall be enclosed in sealed fixtures as required by Wisconsin state electric code. In office or dry storage space, open fixtures will meet code requirements. However if flies are an issue, a sealed fixture might be desirable due to the ease of cleaning. In feed rooms or areas with high amounts of feed dust, sealed dust-proof fixtures are required. Sealed switches are required any place were sealed fixtures are required.

Where should fixtures be mounted?
In agricultural enterprises we need to consider what could hit or come in contact with the fixtures. For example: fixtures mounted down the center of a tie stall barn could potentially be struck by a mounting cow or equipment operation; moving the fixtures over the manure gutter would likely remove much of this potential hazard. However, this may require the use of twice as many fixtures with a single lamp versus two lamps per fixture to provide proper light distribution.

How many fixtures are needed?
The number of fixtures will depend on the lighting level required, type of fixture used, type of lamp used, mounting height, the reflectance values of the surfaces the light will be illuminating, height of the work plane and the amount of variation of light levels that can be tolerated. In general, if a lower number of fixtures is used with higher wattage lamps, more variation of light levels will occur. Lower wattage fixtures will require more fixtures but provide more uniform light level. It is best to work with a reputable lighting contractor who has a lighting design program that can take into account the different parameters and calculate the fixture location and the expected light level variation. Most lighting contractors will have little experience with agricultural requirements so you’ll likely need to provide them with information on reflectance values. Refer to the section on “Applications and design considerations” (pg 6) in UW-Extension Bulletin, “Energy-Efficient Agricultural Lighting“for the recommended reflectance values for your housing type.

If you have questions about the information on this site, please contact
Scott Sanford, Distinguished Outreach Specialist, University of Wisconsin,