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Comprehensive Grow Light Glossary

Comprehensive Grow Light Glossary

When you’re choosing grow lights for your hydroponics setup you may be a bit puzzled by some of the common grow light terms. Here’s a quick glossary to help you get started.

Ampere (AMP)—A unit used to measure the strength of electric current.

Arc—This is the luminous discharge of electricity that occurs between two electrodes within HID lighting.

BU—This is an electrical industry code that means the bulb should only be installed in a base up position.

Bulb—The rounded protective glass structure of an HID lamp which protects the internal arc tube.

Candela—This is another electrical unit. It measures a unit of luminous intensity in one direction. It’s equal to 1 lumen per steradian.

Capacitor—This is an electronic device that’s capable of storing an electrical charge. It’s also one of the main components of an HID light ballast.

Discharge Lamp—A special lamp that emits light by discharging an electrical charge through gaseous metals and gases.

Dome—This is the globular part of a lightbulb. 

Electrodes—These cause arc discharge. There are filaments at each end of a discharge lamp that help maintain an electrical charge between them.

Fixture—This is the part of an electrical device that is attached to ceilings, walls, or standalone, and contains all the electrical components.

Frequency—This is the amount of cycles or waves of electromagnetic radiation per second. It’s measured as Hz—Hertz.

Halogen Lamp—A shorter name for the tungsten-halogen version of lamps. They utilize high pressure incandescent lamps with iodine or bromine gases.

HID—Means high density discharge.

Hood—The silver metal reflective cover that surrounds a halogen lamp.

Ignitor—One part of the ballast that is responsible for starting the bulb in sodium systems.

Illumination—The process of illuminating, such as what is done by a bulb or lighting fixture.

Kilowatt—Measured as kW. One kilowatt is equal to 1000 watts and is a unit of electric power.

Kilowatt Hour—Also known as kWh. This is a measurement of electrical energy. One kWh equals 1000 watts of power over one hour.

Lamp—An electrical device that provides illumination to a room or heat and light to hydroponics.

Mercury Vapor Lamps—These are special lamps that use mercury vapor to arc electricity. More efficient than other types of lamps, including halogen, fluorescent, and incandescent lights.

Neck—The thinnest part of the HID bulb.

Photoperiod—Also called daylength. This is the percentage of light to dark periods within a 24 hour clock.

Reflector—The part of an HID lamp’s reflective hood.

Socket—The metal, threaded structure that the lightbulb is screwed into.

Transformer—A part of the ballast that is responsible for converting electric current from one voltage to another. 

Ultraviolet—Also called UV. This is a type of light indiscernible to the human eye. It has very short wavelengths.

Watt—Also called W. This is a unit of electric power. One watt equals 1 joule/second.