S+LSS Cool Tools: Qualification Testing
Published: October 2011
Structured wiring in commercial buildings must be certified that the network meets industry standards. While there is no comparable requirement for voice/data/video (VDV) wiring in residences, many installers choose to “qualify” a home’s local area network (LAN). Tests that document an installation meets industry standards and component manufacturer’s installation requirements allow extended warranties to be offered and reduce returns for repairs. Contractors with the ability to perform qualified installations have a marketing advantage over competitors who lack that capability.
Qualification applies to security, fire, and alarm systems and VDV wiring.
“It is important to verify that each device on a LAN—whether part of a security system, HVAC control or entertainment network—can communicate with its host,” said Dan Payerle, Ideal Industries business unit manager.
Today, category-rated communications cabling is a standard component in virtually all new residential construction, Payerle said. Beyond the scope of entertainment and lifestyle devices, category cabling is being installed to control security, alarm, mechanical and environmental systems.
“Many providers of security system monitoring offer services in addition to standard alarm functions, including perimeter protection, which allow residents to control their systems, view security cameras, and lock or unlock doors via the Internet,” Payerle said. “These systems rely on cameras, locks and control panels inside the home that communicate with each other via Internet protocol [IP] over category cabling. With all of these media and system devices operating over category cabling, the need to test is more important than ever.”
Because the use of fiber cabling within home systems is not widespread, Payerle said most residential VDV systems are on copper, and the tests and tools for home networks apply to all components, including security and safety.
“When dealing with IP-based systems, there is nothing special about the testing required for security systems,” Payerle said. “An important consideration is the location of security devices relative to normal networking equipment. While network devices and PCs are located on desks or in equipment racks, a CCTV camera will be mounted on a ceiling or on a pole in a precarious position. Because of this, security professionals prefer to have lightweight, integrated handheld test devices. Juggling multiple test devices on an extension ladder is not safe for the technician or the equipment.”
Home network qualification begins with verification of cabling connectivity, Payerle said. Wire map testing ensures the cabling is connected properly from one point to another, but it does not confirm that connection to the network or Internet is available.
He said the verification that the cabling is correctly terminated is performed with a wire mapping or VDV tester. These testers confirm that each of the four pairs of a category cable are terminated in accordance with the TIA-568-C wiring specifications. Within the TIA-568-C standard, there are options for two color codes known as the 568-A and 568-B wiring configurations. A VDV tester with a color screen may have an option to display the wire map in the appropriate colors, which can simplify troubleshooting, but any tester will display an error if a cable is accidentally terminated with 568-A on one side and 568-B on the other.
The next step, service testing, requires the use of a more advanced tester commonly called an Ethernet or LAN analyzer. To perform service testing, each link in the network must be connected to the LAN, and the equipment (servers, router, etc.) should be operating. The LAN analyzer is connected to the network in place of the device that is going to reside at each location, such as a security camera, thermostat or alarm panel. The LAN analyzer connects to the network and runs a series of tests to verify that a device at that location can connect to a local server or to the Internet, depending on how the analyzer is configured.
Payerle briefly described the tests usually involved:
• Link tests connect the tester to the Ethernet switch and report the service speed in megabits per second (Mbps), which usually is 100 or 1,000 with current systems.
• Dynamic host configuration protocol (DHCP) tests verify that a device can connect to a server, which issues and manages individual IP addresses on the network.
• Ping tests send packets of information—usually three—to a network device to verify that data can travel through the network to a specific target. Ping tests result in a response rate and average, minimum and maximum response times. Many installers prefer to ping Google since it is almost always up and responds very quickly. Some companies’ Internet servers do not respond to ping requests.
• Trace-route tests are more advanced than ping test. Trace-route tests find delay times between all routers from the test location to the target server.
LAN analyzers also can perform other important tests that save troubleshooting time, Payerle said. One particularly useful test is power over Ethernet (PoE) presence testing, load testing and monitoring. PoE technology sends direct current (DC) power over a network cable to run small devices, such as phones, cameras, wireless access points and small control panels. PoE load testing is important because the voltage available at the end of a network drop depends on the gauge of the wire and the length of the run. A PoE load tester will apply a load to the PoE supply and tell the operator how much voltage, current and wattage is available at the outlet. So what kinds of LAN analyzers are there?
Ideal’s VDV PRO LAN installation tester checks for wire map errors on telephone, data and coaxial cable. It measures the length of a drop or amount remaining on a spool and features a tone generator and port blink function for tracing. The LanXPLORER PRO LAN management tester verifies the operation of network devices, identifies each device, measures total and device bandwidth consumption, tests PoE/PoE+, identifies the source of network errors, and provides documentation to prove network functionality.
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at email@example.com.