Digital Video Recorders (DVR) with outdoor-mounted CCTV security cameras are prime targets for lightning depending on where the cameras are installed. A lightning strike can destroy outdoor-mounted cameras but can also damage, if not destroy the DVR from a surge traveling through the coax and power wiring. Often, even when the building where the DVR is located has sustained a lightning strike, the video capture board and other equipment may be damaged or destroyed. A lightning strike has much the same effect as a large power surge and therefore the information below also pertains to power surges.
Though there is no guaranteed way to protect your customers? DVR from lightning strikes and power surges, there are a few simple and inexpensive ways to reduce the chance of your customers? DVR being harmed.
Mounting: A camera mounted on a building should be grounded to the buildings structural steel, as close as possible to the camera using a 1_ inch copper strap. By grounding the camera properly, the risk a power surge traveling down the coax to the DVR is greatly reduced. It is important to note that in many cases the camera may still be damaged from the lightning strike due to the current traveling through it and/or heat but at least you have saved the DVR.
Power Supply Panels: Using a power panel instead of individual power supplies to power cameras helps to reduce the damage caused by power surges. All PSG power panels are fused and therefore offer some protection from power surges. However, power panels should always be used in conjunction with a surge protector (see description below) and/or UPS (see description below) for maximum protection for two reasons:
Large power surges (such as lightning) have the ability to be powerful enough to ?jump? between terminals where even a fuse has blown.
A UPS will help to ensure that video is not lost during power surges, lags or lightning strikes. (keeping in mind, all cameras and DVR must be powered through a UPS to not lose any video recording)
A DVR is rarely damaged by a direct lighting strike but is often the victim of a power surge coming from the power cables and/or the coax cable(s). Two essential pieces of equipment to help prevent damage to your DVR are:
Surge Protectors: The main function of a surge protector is to protect the DVR from a power surge. A power surge (or transient voltage) is an increase in voltage above 120 volts, the standard voltage in North America. Electric current travels from point to point due to a greater electric potential on one end of a wire than the other. It uses much the same principle that makes water under pressure flow out of a hose ? higher pressure on one end of the hose pushes water towards an area of lower pressure.
A surge can damage or destroy a DVR in a fraction of a second much the same as too much water pressure can cause a hose to burst. The wires heat up weakening them decreasing their longevity and in cases of larger surges, the wires will burst causing a failure. A surge protector prevents this from happening by detecting the surge and then diverting the extra electricity into the power outlet?s grounding wire.
UPS (uninterruptible power supply): A UPS can protect a DVR against up to three types of power abnormalities: 1) Power surges ? when voltage rises above 120 volts 2) Voltage lags ? when voltage drops below 120 volts 3) Power failure ? no power situation from a line down, grid problem, etc..
There are two common types of UPS; a standby UPS and a continuous UPS. A standby runs the DVR off the normal power supply until it detects a problem while a continuous, the DVR is always running off the battery power of the UPS and the battery is continuously being recharged. Standby UPS?s are more common because they are usually smaller and less expensive than a continuous. The advantage of a continuous UPS is that the DVR will always be receiving the optimum voltage no matter what short-term or long-term power problem might exist. The standby UPS only kicks in when a problem persists meaning smaller surges and lags don?t necessarily trigger the standby UPS to kick-in and therefore damage may still occur.
When installing a DVR at a new site, it is important to ask your client a few questions:
How often are there power failures?
Are there any known power problems at the site?
Does the building ever get hit by lightning?
Have there been occurrences of electronics failing in the past?
As mentioned at the beginning of this article, there is no 100% for sure way of preventing damage caused by power surges, lightning, etc? However, properly grounding outside cameras that are powered by surge protected power supply panels and plugging the DVR into a UPS which is plugged into a surge protector can minimize the chances of the customers DVR being damaged or destroyed.