Are You a Good Supervisor?
Are You a Good Supervisor? If you have been following my writings through the years, there has been a topic that consistently appears in almost every article. This way of thinking is not only an important practice for security professionals, but it is woven into the very fabric of professional security performance and reliability. I am referring to the art of supervision.
Too often the novice security professional installs and places into operation a device that is unsupervised. The device is expected to operate perfectly, but what if it doesn’t? Will anyone know, or will the customer be the first to find out when an alarm goes unreported? In many cases, such as fire and life safety, this could be a fatal flaw.
Guarding Against Device Failures
Anytime a technician, installer, manager, security director or any other security professional 
applies a security device, they should immediately consider what would happen if that device goes bad or is compromised.
Who would be notified and how? Is there more than one means of communication for supervision in case one path fails? Have different levels of supervision been offered to the customer with different costs? How well does the customer understand the level of supervision they are getting? Have they signed off on it?
Most engineers learn early on the importance of supervision, or feedback, in system design. System feedback can be presented in many ways such as local visual and audible signals, and the reporting of remote locations such as the central station and via cell phone to customer and/or service organization.
There Are Many Ways to Keep Tabs
Let’s take a look at the places in which the security profession relies on supervision for reliable system and operation performance
AC power — What happens if you lose AC power to the alarm panel? Locally you should see a visual and audible indication of power loss. If the panel is secluded there are remote indicators, such as a keypad, that will bring the condition to the attention of daily local traffic. Should I monitor for AC power failures? Remember this can overwhelm a central station in the case of massive electrical grid power failures. Any form of supervision has to be weighed carefully. What alternatives are there? Possibly low battery reporting would be a better choice. What other indicators to help verify AC power is present? You might want to look at installing a plug-in transformer that has LED AC power indicators built in.
Motion sensors — These need to look at supervision for both circuit trouble and performance compromise. Common PIR sensors leave themselves open to compromise by simple masking. Have you discussed devices with anti-masking supervision with your customer? Additional tamper supervision can be achieved by having one device look at another device. Are all the tamper and electrical (end of line, or EOL) features being used? Is alternative methodology such as dual technology being used for extra mask detection?
End-of-line (EOL) resistors — Remember an alarm sensor should report three states: normal, alarm and trouble. The alarm panel is expected to see a certain voltage level per alarm zone for these status conditions. This is often accomplished with a properly installed EOL resistor (see photo). You can order EOL resistors already installed in window and door proximity sensors. They help report tampering and faults in alarm sensor circuits. Has the panel been programmed for circuit supervision? Is the resistor installed at the end of the circuit and not in the alarm panel?
Circuit polling — This is done by data packets being sent through the circuit on a predefined time interval. Any disruption in the circuit will upset the expected signals being polled.
Wireless test — A process in which a wireless polling signal is sent to the alarm panel receiver from the wireless alarm sensor. Trouble is reported if an expected test signal is not received. 
Since wireless signals can be affected by movement of metallic objects such as file cabinets, refrigerators, etc., it is important to constantly supervise the wireless paths of communications. New “mesh”-type wireless systems are more reliable since they have many alternative paths of communication.
Network supervision — Another area to consider now that so many security devices are connected via computer networks. Working with resident IT personnel you might want to consider third-party software such as Easy Network Service Monitor by Javvin (www.javvin.com) or hardware devices such as Lantronix’s IntelliBox® (see Tool Tip).
RJ-31X telephone/alarm system interface — If installed properly, these can be unplugged from the alarm panel while still allowing the phone system to continue operating properly. However, alarms will not report via the phone line to the central station. A supervisory connection should be made by placing an EOL resistor across pins 2 and 7 (see photo), and connecting the EOL resistor to a 24-hour alarm loop. If someone pulls the RJ-31X plug, at least a local alarm enunciator will indicate trouble with the phone connection.
Phone line — This supervision comes in a couple of flavors. One is a polling signal reporting a test signal to the central station that it expects to get from the alarm panel within a fixed period of time. Another form is the alarm panel testing for phone circuit battery voltage; however, this can easily be compromised and does not ensure central station reporting.
CCTV circuits — These can be supervised for signal loss, thereby notifying an operator that a video signal is no longer being received.
Tamper switches — Although they are everywhere, they are not always used. Make sure they are connected to a 24-hour tamper circuit and supervised, preferably with EOL devices.
Shunting — This is a method used by some techs to remotely void out an alarm sensor. Use the opposite set of contacts to create a supervision circuit to remind users the circuit is still shunted.
Low battery reporting — Another option is to supervise the status of an alarm battery. Has this option been set in the panel? Do the alarm panels you install actually perform a periodic load test of the battery? On larger integrated systems many UPS units have reporting capability as well.
Unrestored signals — These can be monitored at the central station. This provides supervision to identify that a previous alarm has been properly restored to a normal state within a certain period of time. Supervision like this is especially important with life-safety monitoring.
Testing and maintenance (glass-break detectors) — Not always thought of as a supervision function, but it is important to be able to test all sensors on a regular basis. This often cannot be done through automation and must, therefore, include regular manual testing.
I Stand Corrected In the July “Tech Talk,” the reference to the Lantronix SCS400 was in error. The product was actually the Digi-Connect® WI-SP from Digi Int’l Inc. which was also depicted in a diagram.
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