Landscape Lighting USA

What is AC current and how does it differ from DC current?
AC Current (Alternating Current) is electrical current in which the direction is reversed at regular intervals or cycles; in the U.S. the standard is 120 reversals or 60 cycles per second. DC Current (Direct Current) is a type of electrical current and distribution by which electricity flows in one direction the conductor. Battery operated systems are typical DC applications.

What is a color rendering index or CRI?
This is an index from 0-100 measuring a light source’s ability to render color accurately. Sodium lamps can have a CRI as low as 22, while tungsten halogen lamps can have a CRI as high as 100. Any lamp rated above 80 CRI tend to be good color rendering.

What is the definition of footcandle or (fc) and how does it compare to Lux (lx)?
A footcandle is a unit of luminance. One footcandle is equal to one lumen per square foot (lmft2). A lighting designer would use a measure of footcandles at the work surface to determine the proper illumination level for home or office lighting. Lux is an international metric unit of luminance. One lux is equal to one lumen per square meter (lm/m2)

What is a kilowatt or (kw)?
A kilowatt is a measure of electrical power equal to 1000 watts.

What does average lamp life mean?
Average lamp life is a value for life expectancy based on laboratory tests using controlled system characteristics measured in hours where 50% are still operating.

What is Correlated Color Temperature?
This is a scientific measurement of the balance between the wavelengths making up any “white” light. The unit of measurement is in Kelvin (K) which determines the warm or cool appearance of a light source. The lower the color temperature, the warmer or more yellow is the appearance. The higher the color temperature, the cooler or bluer is the appearance. Typical color temperatures are 2800K for incandescent, 3000K for halogen, 4100K for cool white, and 5000K for metal halide and daylight fluorescent lamps.

What is a ballast factor?
The percentage of rated lumens from the same lamp using a commercial ballast as compared to an ANSI reference ballast. A ballast factor of .96 means the commercial ballast produces 96% of light produced by an ANSI reference ballast operating the same lamp. The ballast factor can be referred to in the catalogs from fluorescent or HID ballast manufacturers.

Who is the American National Standards Institute (ANSI)?
This is a professional organization that coordinates voluntary guidelines and standards for lighting, electrical and other industries.

What is rapid start ballast?
This is a type of fluorescent ballast that applies a low filament voltage to preheat the cathodes. Simultaneously, a starting voltage (lower than that used in instant start ballasts) is also applied to strike the arc. When the cathodes are hot enough the lamp will strike.

What does high power factor mean?
This is a measurement of the effectiveness of which an electrical device converts amperages to watts. Power factors can range from 0 to 1.0. A high power factor means that the electrical system is utilizing the power efficiently. Devises with power factors of greater than .90 are considered “high power factor.”

What is voltage?
Voltage is the force or pressure of electricity. For incandescent and halogen lamps, voltage generally refers to the line voltage of which the lamp should operate. For HID, fluorescent, and low voltage lamps, the voltage generally refers to the operating voltage is connected to a power supply (ballast or transformer) after it is warmed up.

What is Ohms law?
Volts X Amps = Watts

What is a watt?
A unit of electrical power used to indicate power consumption.A unit of frequency equal to one cycle per second.

What are Initial lumens?
This is the quantity of light output measured after the first 100 hours of operation using controlled system characteristics.

What is the definition of Mean Lumens?
Average quantity of light output over the life of the lamp. High pressure sodium and incandescent lamps are measures for mean lumens at 50% of lamp life. Fluorescent and metal halide lamps are measured for mean lumens at 40% of rated lamp life