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Index1.Networking Systems//Video Products//Video Security Systems
Tech Tips
Protecting Your Security Equipment Against High-voltage Surges
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Technical Information & Standards
A Lightning Rod of Security
The proliferation of externally mounted IP-based network cameras is increasing the risk of fire, damage or
serious injury and death caused by a high-voltage surge event such as an incidental lightning strike or a
power line cross. Because the dense charge of positive electrons residing on objects protruding from the earth
attracts the negative charge from a lightning strike, outside network cameras on rooftops and light poles
become a focal point for the high-voltage discharge, which can easily exceed 5,000 volts. Instead of drawing
the charge to the earth, these cameras act as virtual lightning rods, drawing the high-voltage current to the
data center or telecom room through the copper cabling infrastructure.
Without proper protection, a 100-volt shock lasting a few nanoseconds can seriously damage or destroy valuable networking equipment. Unlike telephone lines, current
standards and codes governing building entrance protection are ambiguous in their requirements for IP-based outdoor network cameras. This lack of installation
standardization continues to expose sensitive networking equipment within the building structure to damage from a surge of voltage or current.
The Evolution of Networking Configurations
This threat comes from the evolution of the video surveillance network from a standalone configuration to an integrated system utilizing a single cabling network. In
traditional analog video surveillance systems, a single coaxial cable runs from a camera directly back to the video headend. In a networked video surveillance system,
all of the IP-based cameras are attached to the same network, which runs back to a telecom room or data center where mission-critical equipment is kept. Although an
overvoltage can damage both analog and IP cameras and the equipment to which they are connected, IP video cameras can also cause damage to critical Ethernet
network components and infrastructure that resides on the same network.
Best Practices for Safeguarding Network Equipment
To prevent damaging the networking equipment in this scenario, we recommend following Article 800 of the National Electrical Code, which specifies the installation of
primary protection for all conductive communications paths entering or leaving a building, but no more than 50 feet past the building entrance. The article recommends
using a UL 497 Listed primary protector. Using a solid-state module rather than a traditional gas-tube module is recommended because of its much faster clamping time
during a high-voltage surge event and its increased longevity. Even after multiple surge hits, solid-state modules don't typically need replacing. Lastly, the use of a UL
497A secondary protector will mitigate further risk of equipment damage from voltage surges that were not eliminated using a UL 497 primary protector.
Power Protection and UL, What Does It Mean?
Different UL Listings mean different things for good reasons, safety. The highest UL Listing for surge protection products is UL 497, which can be easily confused with UL
497A and UL 497B. Here is a look at the difference:
UL 497 or Primary Protection: The Primary Protector is used at building entrances and is capable of withstanding the highest level of overvoltage surges,
lightning. These devices are required by NEC Article 800 to protect buildings and humans.
UL 497 A or Secondary Protection: The Secondary Protector is located between the building entrance/primary protector and the equipment intended to be
protected. These protectors are intended to protect buildings, humans and sensitive electronic equipment.
UL 498 B or Isolated Loop Protection: Isolated Loop Protectors are designed to handle overvoltage events which are introduced within a building. The
protected "loop" must not be exposed to the outside world. These protectors are not designed to protect against lightning-type surges but are for
low-voltage protection only.