In our last blog, you learned The Biggest Problem with Today’s Perimeter Security Lighting is that legacy pole-mounted security lighting was never designed with perimeter security lighting camera systems or on-site security personnel in mind. It was meant as a passive defensive that would—in theory—keep intruders away. The logic was, “If it’s lit, it’s safe.” But, as we know now, there are tons of problems with improper legacy pole-mounted security lighting including the old-fashioned “more light is better” mantra, which we debunked in our previous blog. Let’s take a moment to take a deeper dive in what factors contribute to making most perimeter security lighting inferior and CAST’s innovative solutions.
Glare
Glare is a result of artificial light. It occurs at night when the human eye is most sensitive, which is an important factor to consider when designing any high-security lighting system. Glare isn’t only a problem for the human eye, but also CCTV cameras. Virtually all legacy pole-mounted lighting systems create glare.
Disability Glare Vs. Discomfort Glare
It is important to define the two types of glare: disability glare and discomfort glare. According the IESNA, disability glare is the effect of stray light in the eye whereby visibility and visual performance are reduced; discomfort glare, on the other hand, produces only discomfort and may not interfere with visual performance or visibility. Disability glare causes the light-sensitive rods and cones of the eye to become temporarily overloaded, which renders an individual momentarily blind and susceptible to attack. The resetting of the human eye, or adaptation to darkness, can take anywhere from 15 to 120 seconds depending on the severity. This blindness creates vulnerability for onsite security personnel and should be eliminated or significantly reduced. That being said, disability glare can be a useful tool against intruders, which we will discuss in the second blog of this mini blog series. In addition to eliminating disability glare, the right light level must be delivered to allow the eye to adjust to the artificial light and become comfortable in the night setting. This eye/site acclimation allows the individual to see into the surrounding darkness, become better aware of the property, and pick up movements that otherwise would be undetected. The improved lighting condition allows security to identify and respond more rapidly to threats than in a glare-filled environment. Glare must also be avoided with all cameras as it reduces resolution quality and increases image contrast, making it more difficult to review captured footage. CAST Perimeter™ Security Lighting uses glare-free technology to avoid unsafe situations that create vulnerability, breaches in security, and poor image capture.
Shadows
Mounting fixtures 25 feet or higher on large pole lights that are typically spaced 100 or more feet apart unquestionably creates shadows with low plant material and provides intruders a place to hide. The better solution is placing fixtures directly on the fence line at a lower mounting height with fixtures spaced 20 to 30 feet apart to reduce or eliminate these shadows. The result: better overall lighting and the reduction of cover for perpetrators to hide in.
Difficulties with Illuminating Tight Mesh Anti-Climb Fencing & Walls Using Legacy Street Lights
Most cyclone fencing provides ample open mesh space allowing in light and an unobstructed view of a property. This allows for active on-site security monitoring inside and outside the fence line. With the hardening of the fence line at many critical facilities such as airports, military installations, and substations, the fence height is often increased from 8 feet to 10 feet, and incorporates tight anti-climb fencing to create a nearly impenetrable perimeter line. Often times, a “louvered mesh”, composite thick cell or a tight-wire cell is used to prevent any hand holds for a perpetrator to use to scale the fence. This is a great way to secure the perimeter, but proves challenging to illuminate with conventional street lights as the new high-security fence systems allow little light to pass through, especially at a 45-degree angle from the light source which occurs between street light spacing. As a result, dark shadows are created—an ideal place for intruders to hide. The darkness on the outside of the fence starts at the top of the fence and extends outward to the base. Distances of exterior fence darkness on the exterior of the fence are as little as 10 feet to as much as 20 feet depending on the mounting height of the fixture and the distance the street lights are mounted inside the fence line. We recommend placing the street lights directly centered over the fence line, which requires precise construction, extensive fine tuning, and the ability to problem solve and create custom solutions for turns along the fence line usually situated on uneven site conditions. Such circumstances can make effective security lighting using legacy pole systems extremely difficult and extremely expensive. See Figure 1.1 for further details. CAST lighting was the first perimeter security lighting system designed specifically for the fence line as well as these new tight mesh fence systems. This is achieved by providing even illumination on both the inside and the outside of the fence line, eliminating any space a perpetrator can hide while also producing better camera images and an overall better security lighting solution: The CAST solution is easier to install, easier to maintain, and provides 60 to 80 percent savings in materials and labor to the end user compared to legacy pole mounted systems.
Reflectivity & Changing Surface Conditions
Unfortunately, reflectivity and changing surface conditions happen all the time. Closed-circuit camera systems struggle with the reflectivity of changing ground conditions caused by rain on plant materials, puddles that create mirrored surfaces, and the reflective value of white snow. Overly-illuminated areas cause these conditions to worsen significantly, which interfere with camera images by creating unwanted glare. The CAST Perimeter™ Security Lighting system delivers the right light level, reducing this potential problem before you even knew it was an issue.
Understanding How to Produce Better Security Lights
As you can see, glare, reflectivity, changing surface conditions, and shadows all play a large role in impacting the effectiveness of a perimeter security lighting system. In the second and final blog of this two part series, we will examine horizontal and vertical illuminance, the uniformity of light distribution, lux levels, how the human eye interacts with light, camera imaging, CAST’s solutions to the biggest issues troubling the industry, and how to develop the best defense using perimeter security lighting.
