Weather-proofed surveillance: protecting your system from Mother Nature
Natural disasters get a lot of media attention – and recently there seem to be more stories than ever about flooding, blizzards, tornados and tsunamis. But since most installations are done when weather conditions are close to ideal, Mother Nature can be a forgotten aspect of the install. Is your surveillance system prepared to withstand the worst weather and survive when it may be needed most?
The five biggest environmental threats to your security system are: lightning, water (in all forms), wind, temperature extremes, and dust.
Lightning is one of nature’s most fatal yet instantaneous events. Cloud to ground lightning typically follows the path of least resistance, which is why it’s not a good idea to hide under a tree during a storm on a golf course: the tree’s height makes it a more likely target for lightning to enter the earth.
This same logic applies to cameras mounted on poles or high up on your building. Not only is the camera itself a likely target, but any type of connected copper wire could be damaged by a strike. If using copper-based twisted pair wiring outdoors, conduit should be used for protection (or fibre optics is another choice – see June 2010 article on wiring beyond 100 metres). But whether you are using wireless connectivity, fibre optics, or plain old copper wire for Cat 5/6 twisted pair infrastructure, all wiring needs to be protected from power surges. Just like a fire break, you need a circuit that can be blown by the lightning strike and block the voltage path from entering your building.
Another best practice dictates using proper grounding to give the lightning a separate, safe path to travel to its end-point in the earth. In particularly lightning-prone areas you could use lightning suppressors, which can be found at most electronics outlets and distributors.
2011 has been the year of the flood thus far with record levels occurring in many areas of Canada and the U.S. But while total protection against a major flood is neither realistic nor cost-effective, you can still protect yourself from common water problems such as rain, snow, and ice.
Using a proper IP-rated enclosure will protect your camera from wind driven rain and keep out snow (see chart). An IP66-rating will protect you against a powerful water spray, while a rating higher than IP66 protects the enclosure from water immersion – although there are very few surveillance installations that call for underwater cameras. Like lightning, water will always find the path of least resistance, so even the smallest opening in your camera is at risk. This is why it is so important to install the rubber grommet that comes with most outdoor cameras to seal the opening where the Ethernet wire enters the camera housing.
In the winter, ice storms can wreak havoc with your enclosure’s temperature rating on the lower end. Even though ice storms at -10°C and below are extremely rare, when the temperature drops suddenly and the moisture on the cover rapidly freezes, your camera will be effectively blinded. Your -40°C-rated enclosure may only be warm enough at -10°C to actually melt the ice. If you are in an area where ice storms occur at very low temperatures or where rapid temperature drops are commonplace, make sure to verify the specific rating for your enclosure in these situations.
Wind too can have nasty effects, especially when speeds top 100km/hour. Although you cannot cost-effectively protect against F5 tornadoes or Cat5 hurricanes, there are special considerations to make outdoor mounted cameras usable during wind events.
One common feature found in network cameras is called electronic image stabilization. The computer in the network camera can adjust the image when the camera is swaying in the wind and cause the video to appear stable. But in extremely windy situations image stabilization may fall short and, if you’re using motion detection, its violent movement may cause false alarms.
To protect against these wind events, ensure your pole strength is appropriate for your camera. A fixed camera will weigh much less than a pan/tilt/zoom (PTZ) camera, therefore your pole strength for a fixed camera will be less than for a PTZ. What you should measure is the pole’s deflection in degrees (i.e. how far the pole can sway from its upright position). The thicker the pole combined with the load on the pole will determine your deflection range and help you maintain a stable image. Lastly, don’t forget to confirm that the material in the bracket is appropriate for this environment.
Protecting against temperature extremes is straightforward and rather commonsense. Here in Canada people often look at -40°C as the benchmark to protect against the cold on the lower end of the temperature scale. Canada is the second coldest country in the world, after Russia, but Canada’s major metropolitan areas rarely have core temperatures this cold. Weather reports that claim extreme cold usually take into account wind chill, which luckily we don’t need to worry about for installs. Look at your city’s weather charts to see what the yearly extreme low temperatures are and plan accordingly.
Higher temperature extremes happen across the globe, both in typical hot spots as well as normally temperate places like Canada. Especially during the solar summer, direct sunlight over time will make the camera even hotter. Even on a regular day of 30°C, the enclosure of a rooftop camera baking in the sun can easily exceed 50°C. This temperature will normally fry electronic components. Make sure your enclosure has a fan to move the heat away from the camera and into the atmosphere. In real extreme weather you will want to get an automatically cooled enclosure – cooling by air or liquid.
Heat is usually accompanied by our final weather nuisance: dust. Recently we saw dramatic pictures of the dust storm that engulfed Phoenix, Arizona. While protecting against a once-in-a-lifetime event isn’t prudent, dust in its every day form poses a threat to your network surveillance system. Dust is microscopic and can find its way into all types of openings that will harm your camera’s performance. If you are in a dusty environment – either outdoors or indoors – you want to use the right IP-ratings for your enclosures. An enclosure IP-rating with the first digit of six will completely protect against dust entering the camera.
Although no system will ever be fully protected from the power of Mother Nature, these considerations will help you build a network camera system to survive the storm. Who knows, if done right, maybe your video will be the next viral sensation of “Wild Weather, Caught on Tape.”
Robert Moore is Canadian country manager, Axis Communications Robert.Moore@axis.com