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Lighting is primarily a large portion of what we do day to day. This is also something that an apprentice is heavily relied on for. We need you to become familiar with common terms and products so that you'll understand why you are installing, and where you are placing different fixtures.

Lighting Definitions
Quality of light - Color rendering index (CRI) is the ability of a lamp to render object colors.
-color spectrum differences of cool white versus warm white.

Lux-One lux is equal to one lumen per square meter. This is the amount of aluminance on a surface.

Foot candles-1 ft. candle is equal to one lumen per square foot. One foot from a candle.

Lumens-a measurement of flux or quantity of light given off by a source.
Overview of lumens

Incandescent Lamps 10-40
Halogen Incandescent Lamps 20-45
Fluorescent Lamps 35-105
Mercury Lamps 50-60
Metal Halide Lamps 60-120
High Pressure Sodium Lamps 60-140
Low Pressure Sodium Lamps 140-180

Ballast - supplies the start up electricity needed to excite the gas in the tube, then regulates the amount of electricity to keep the light going. This is done with a capacitor within the ballast that corrects the power factor. This is especially helpful, if there are many lights being utilized.

Correlated color temperature-is a number given in Kelvin's to represent the color temperature of a lamp. The higher the temperature the bluer (or whiter) it will appear. The lower the temperature the warmer it will be.

2000 K (Warm)
4000 K (Cool White)
6000 K (Daylight)

Efficacy-a measurement of how effective a light source is to convert electrical energy to lumens of visible light. The ratio of input vs output. For instance, a fluorescent bulb @ 30 watts at a lumen rating of 60.

As electricians we use a wide variety of lamps, or bulbs. Here is a very basic outline of commonly used bulbs, and some of their features to give a guideline...

Here is a breakdown of some of the HID (High Intensity Discharge Lamps that we use on commercial jobsites.

Mercury Vapour Metal Halide High Pressure Sodium Low Pressure Sodium
25,000 hrs. 20,000 hrs 18,000 hrs 18,000 hrs
25-55 CRI 60-70 CRI 20-25 CRI 0 CRI
30-65 lumens/watt 65-120 lumens/watt 140 lumens/watt 180 lumens/watt
no ignitor may have ignitor no starting electrode neon starting gas
slow startup 3-7 mins faster startup and restrike very high voltage strike (2500V of higher)
15 minute restrike whiter light ceramic inner tube
phosphor coated increases light output position sensitive high uv
high uv output higher efficacy
2 1 3 4 CRI
4 3 2 1 Efficacy

This is a basic troubleshooting guide for fluorescent fixtures. We deal with these problems regardless of a new installation, or regular maintenance. These will become very familiar to you throughout your troubleshooting training.

Troubleshooting Fluorescent Fixtures (In order of occurance)
Lamp won't come on Lamp shivers or flickers
- lamp failure - 1,000 hrs seasoning process
- poor contact pins - starter
- too cold - too cold
- ballast failure - 1 lamp failure
- poor ground
Humming Noise Very Low Starting
- ballast not tight against case - too cold
- ballast is failing - starter is gone
mixed equipment (tubes vs ballast)
- end of life of tubes
Ballast Heats Excessively Discoloration (Near Ends)
- leaking - end of life of cathodes
- ballast is failing
-wrong wattage tube
- high voltage