The lumen (symbol represented: lm) is the International System of Units of luminous flux, which is the measure of the perceived power of light to the naked eye. Luminous flux is much different than the radiant flux which is the measure of the total power of light emitted from the light bulb, in that lumens are adjusted to show the varying sensitivity of the human naked eye to different wavelengths of light.

For example standard 120 V, 60 watt incandescent light bulb emits 600-800 lumens, but a simliar 13 watt compact fluorescent lamp emits the same amount of lumens.

Bulb Ballast typically 2-5 times as long as the lamp. (i.e. Sign Ballast)

The Crest Factor is an easy and useful calculation that gives the person analysing a good idea of
how much impacting is occurring in a time waveform. This can be useful information that is
lost if one is only viewing a spectrum as the FFT cannot distinquish between impacting
and audible noise. In many cases, the Crest Factor is measured over time to see if the amount of impacting is increasing or decreasing.

HPS Systems are very efficient—about 100/110 lm/W—when measured for photopic lighting conditions. They are commonly used for outdoor lighting (HPS Fixtures) such as streetlights and where security lighting is needed.

Xenon at a very low pressure is needed as a “starter gas” in the High Pressure Sodium lamp. Xenon has one of the lowest thermal conductivity (Xenon) and the lowest ionization potential of all the non-radioactive noble gases (The noble gases are a section of chemical elements with like properties: under normal conditions, they are all odorless, colorless, monatomic gases, with a very low chemical reactivity. ). As a noble gas, because they are so stable, do not interfere with the chemical reactions in the fully operating HPS lamp. Most HPS Lamps require 5-10 minutes to reach full brightness.

Oil-filled capacitors
Oil-filled capacitors have metal cases and have dielectric fluid in them. Oil-filled capacitors are rated up to 100°C, although 90°C is the most common rating used today. They typically have two 1/4″ spade terminal connections that are located on the top of the capacitor for connection with the HID ballast. Most HID ballasts come with the matching terminals that is attached to the appropriate terminals. Oil-filled capacitors are extremely reliable and have ratings up to 525 Volts. In many higher (1000W +) wattage HID ballasts, they are the only choice.

Dry-Film capacitors
Dry-Film capacitors do not contain dielectric fluid. Most of these capacitors are rated up to 400 Volts. Many are available in ratings of 100°C or more. Dry-Film capacitors have become increasingly attractive alternative to oil-filled capacitors. Dry-Film capacitors are packaged in thermal-plastic housings and do not need to be grounded. A lot of manufactures are doing away with Oil-filled capacitors due to expense and environmentally sound practices.

Kelvin scale comparative values of light sources.

Here is a list gives you an idea of where some light sources are relative to one another on the Kelvin scale.

In buildings, it is very important to take the color temperature into consideration of the light fixtures (i.e. Metal Halide Fixtures) used. To promote relaxation, a warmer (i.e., lower color temperature 2700K) light is often used in public areas, while a cooler (higher color temperature 4100K or 5000K) light is used in office buildings. Today there is a heightened awareness that poor lighting can cause stress and sick building syndrome.

There is an international color code to show the temperature (CCT) of a light bulb’s light color. This code is a three digit number (i.e. F32T8/741) The first digit refers to the color rendering index: if it is 7, then the CRI is between 70 and 80, if it is 8, it lies between 80 and 90. The following two numbers are the color temperature (to the nearest hundred) divided by 100 kelvins, and if the temperature is 6500 K (full spectrum), the number is 65.