Most commonly associated with outdoor flood lights, there are many options to choose from when designing an outdoor security lighting system.  The most well-thought systems combine a mixture of lights designed for continual use with those designed to instantly switch on and and automatically turn off by means of a motion sensor detector.  When properly implemented, the lamps should not only act as a deterrent against potential crime and mischief, but also allow homeowners to clearly see objects in the lit areas.

Baby night lightMost commonly associated with outdoor flood lights, there are many options to choose from when designing an outdoor security lighting system.  The most well-thought systems combine a mixture of lights designed for continual use with those designed to instantly switch on and automatically turn off by means of a motion sensor detector.  When properly implemented, the lamps should not only act as a deterrent against potential crime and mischief, but also allow homeowners to clearly see objects in the lit areas. 

Many lamp varieties are used in outdoor security lighting.  Which lamps you decide to use is going to depend, at least in part, on where you want the lights situated and how brightly you want the area lit.  Other factors that will affect your decision are desired light intensity, color rendering index (CRI), correlated color temperature (CCT), lifespan, and energy efficiency. 

Color rendering index refers to a lamp’s ability to faithfully render colors, as compared with a natural or optimal light source.  Daylight is the typical benchmark.  The higher a light registers on this quantitative index, the more capable it is of faithfully producing colors.

CRI does not describe the visible color of the lamp.  That is the job of correlated color temperature.

Correlated color temperature refers to the specific temperature a theoretical light source would need to be heated to achieve a light that produces a color of a reference source of light.  It is measured in degrees kelvin (K).  Kelvin is a unit of absolute temperature; a topic beyond the scope of this article. 

CCT essentially measures the overall warmth or coolness of a lamp’s appearance.  Lower temperatures refer to warmer light sources, and vice versa.  Colors below 3200 K are considered warm (red/yellow/gold), while colors above 4000 K are generally considered cool (blue hue).

Lamps can be broken down into two main types: high Intensity discharge (HID) and halogen.

Here’s a brief description for HID:

HID lamps – have the longest lifespan and highest efficacy of any light source.  Efficacy refers to the amount of light produced as measured against the amount of energy expended in the process.  Simply put, this means they radiate more light per watt of electricity consumed because a higher proportion of their radiation is light, as opposed to heat. 

HID lamps manufacture intense light using an electrical arc.  Electrical arc, in this instance, refers to a process that involves a quick breakdown of the resistance of gas contained within the bulb’s quartz or alumina arc tube.  This arc tube contains both gas and metal salts and the breakdown occurs between 2 electrodes within the arc tube.  Gas is used to provide the initial spark. 

Once sparked, the electrical arc gradually heats the metal salts contained within the arc tube.  The heating of these metal salts forms into a continuous plasma discharge, which greatly adds to the light’s intensity, while at the same time reducing its energy consumption.

HID lights require a ballast: a device used to ignite and harness the current flow within the arc tube.  More specifically, it converts existing voltage into a higher operating voltage in order to spark the gas and metal salts into producing light.  Once ignited, it can sometimes takes 5 minutes or more for the ballast to fully establish the electrical arc.  This means it could take more than 5 minutes for these lights to produce light once activated.