Before installing a surveillance system, we recommend you do a site survey and document it for future needs and upgrades.
There are many building blocks of a site survey, and in this guide we help identifying some of them. One of the first things to define is the purpose of the installation. The physical location and the customer’s needs are two other important things to consider, as well as reviewing the existing security procedures and establish the new ones. What areas to monitor and why, which cameras to select and where to place them, and the current network infrastructure are also key factors for a successful surveillance installation.
In this guide, we present site survey considerations in five steps.
What is a power surge?
A power surge is a transient voltage spike in a power or data line. The most familiar cause is lightning strikes, but it is actually just one of several common reasons.
More frequent causes include the switching on and off of high-powered machinery such as elevator motors or air conditioners. The resulting changes in magnetic or electrical fields around these high-power lines can lead to voltage transients in surrounding cabling.
Surges can also occur as a result of faulty equipment or downed power lines. In today’s complex power distribution system, this kind of event should be considered inevitable.
Electronic equipment is constantly shrinking in scale, and modern, delicate components are increasingly sensitive to excessive variations in current and voltage. If a sufficiently powerful transient enters the equipment, it may become irrevocably damaged and even catch on fire.
Protection
Axis cameras are designed to resist voltage transients to a certain degree. This design depends on proper installation.
The network cable connecting the camera to a switch may pick up strong magnetic and electrical fields in its immediate proximity. This could lead to voltage transients propagating along the cable. Through the use of a shielded network cable (STP), the electric energy is trapped by the shield instead, and can be diverted to ground without ever reaching the camera. This requires that the shield has an unbroken path to ground through the Power Sourcing Equipment (a Power over Ethernet switch or a midspan).
For this to work, it is imperative that the PSE is properly grounded. An Axis PoE midspan should always be connected to a grounded socket for the shield to function properly.
However, a desktop switch like the one shown in the image above may lack a ground connection through the power line; therefore, the switch needs to be grounded separately.
Consider the entire cable path when performing the installation. If you are connecting several network cables together to reach the camera, make sure each cable and all patch panels and couplings are shielded.
Summary
Power surges are an inherent part of the electrical distribution system, and may damage equipment if not handled properly. When installing Axis cameras, use shielded network cables (STP) throughout, and to benefit from the surge-resistant design of the cameras, make sure your switches or midspans areproperly grounded. Avoid running network cables parallel to power lines if possible.
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