Fundamentals &Fundamentals &

TerminologyTerminology

LIGHTING TERMINOLOGY & SPECIFICATIONS

Basic Lamp Types

IncandescentFluorescentMercury VaporMetal HalideHigh Pressure SodiumLow Pressure Sodium

How Lamps Produce Light

Incandescent Fluorescent

HID Low Pressure Sodium

Relative Performance of Lamp Types

Compare: Relative Light Output Range of Wattages Range of Light Output Efficiency or Efficacy Range of Rated Life

Relative Light Output

Lamp Type Relative LightOutput

Incandescent 1.0Mercury Vapor 2.5Fluorescent 4.8Metal Halide 4.8High Pressure Sodium 5.4Low Pressure Sodium 7.7

Range of Lamp Wattages

The range of lamp wattages, and hence light output, is an indication of the scope of applications of each lamp type.

0 500 1000 1500

Incandescent

Fluorescent

Mercury Vapor

Metal Halide

High PressureSodium

Low PressureSodium

Wattages

Range of Light Output

0 50000 100000 150000

Low PressureSodium

High PressureSodium

Metal Halide

Mercury Vapor

Fluorescent

Incandescent

Lumens

The range of light output is also an indication of the scope of applications.

Lamp Efficacy (1)

The ability of a lamp to convert watts into lumens is its efficacy

Efficacy is expressed in Lumens Per Watt

One comparison of efficacy is made by comparing the highest wattage rating of each lamp type.

Lamp Efficacy (2)

Lamp Type LPW (Lumens Per Watt)

Incandescent 22.2

Fluorescent 70.7

Mercury Vapor 60.0

Metal Halide 103.3

High Pressure Sodium 140.0

Low Pressure Sodium 183.0

Range of Rated Life

0 5000 10000 15000 20000 25000 30000 35000 40000

Incadescent

Fluorescent

Mercy Vapor

Metal Halide

High Pressure Sodium

Low Pressure Sodium

Range of Rated Life (2)

Fluorescent, mercury vapor and high pressure sodium lamps have the longest expected life.

Incandescent have the shortest.

Bulbs Types

FluorescentLamps

HIDLamps

Low Pressure Sodium LamsIncandescent

Lamps

Common Lamp & Lighting Terms

Current (Amp or I): The flow of electricity through a lamp or circuit. It is measured in amperes, abbreviated “A” or “I”

Direct Current: In direct current, the flow of electricity is in a single direction. Batteries produce DC current.

Common Lamp & Lighting Terms (2)

Alternating Current: In alternating current, the flow of electricity alternates direction. The current flowing in the circuit goes on and off twice in one cycle.

The number of cycles completed in one second is called the frequency of the AC voltage and is designated by Hertz (Hz). The most common frequency is 60 Hz (60 Hertz).

Common Lamp & Lighting Terms (3)

Voltage (V or E): A measurement of the electrical force or pressure. It is analogous to the pressure in a water line. Measured in volts, abbreviated as “V” or “E”

Resistance (R): The resistance to the flow of electricity. Measured in ohms, abbreviated “R.” It is analogous to the resistance of water flow by a sprinkler at the end of a hose.

Common Lamp & Lighting Terms (4)

Ohm’s Law: The relationship of voltage & resistance. The current that will flow in a circuit is dependent on the voltage applied to the circuit and the resistance in the circuit. Use I =E/R.

Watt (W): The power used or consumed by a lamp. It is the product of voltage applied to the lamp or circuit and the current flowing through it, where the power factor is unity or 1.0.

Common Lamp & Lighting Terms (5)

Power Factor: The ratio of the actual power being consumed by the lamp or circuit to the apparent power being consumed.

Power Factor = Actual/Apparent

The apparent power is the product of the voltage and the current (V x I). Therefore, the actual power equals the apparent power times the power factor

Actual = V x I x PF

Common Lamp & Lighting Terms (6)

Kilowatt: A kilowatt equals 1000 watts.

KW = W/1000

Kilowatt Hour: The unit of energy. Energy use is determined by Energy = Power x Time. Utilities charge for energy used not power consumed.

Common Lamp & Lighting Terms (7)

Transformer: An AC device that transforms the voltage from the supply side to the load side. It can be designed to raise or lower the secondary voltage.

Reactor: A device to limit the current flow to a fluorescent, HID or sodium lamp. It is sometimes called a “choke.”

Capacitor: A device used to correct power factor.

Light Terms

Lumen: Defines the total quantity of light produced by a lamp regardless of direction.

Candlepower (CP): Defines the quantity of light emitted by a lamp in one direction, or the intensity of light in that direction.

Candlepower Distribution Curve: A representation of how light is distributed by a fixture or by a reflector and PAR lamps.

Illumination: The quantity of light falling on a surface. Measured in footcandles.

Light Terms (2)

Footcandle (FC): The amount of lumens falling on an area with the area expressed in square feet.

Lux: The metric equivalent of the footcandle with the area expressed in square meters.

Lamp Color Terms

The color of a lamp is described by two independent characteristics: Color Temperature: The color

appearance of the lighted lamp Color Rendition: How colors appear

when lighted by the lamp.

Lamp Color Terms (2)

Color Temperature (Kelvins, K): The color temperature of a lamp is based on a theoretical object called a black body which when heated, emits light.

At a given temperature, the black body has a distinct color appearance. The heated temperature is measured and the value of that temperature is designated its color temperature.

Lamp Color Terms (3)

Color Rendition: An evaluation of how colors appear when lighted by the lamp. The color rendering ability of a lamp is indicated by its color rendering index rating

Color Rendering Index (CRI): Expresses the relative ability of a lamp to match the color rendering of a standard illuminant. A scale of 100 is used to measure CRI.