Your alarm system provides physical security for your building – but what protects the alarm system?
Introduction
Commercial buildings in the USA typically have two separate alarm systems: (1) the fire alarm, and (2) the burglar alarm. The fire alarm is required by law for safety reasons. The burglar alarm is usually optional. Often, both systems are installed and maintained by the same alarm installation company, but this isn’t a requirement.
Burglar alarms may provide a loud, on-site alarm, such as a siren or bell, and they may send a signal alerting a private security company or the local police. The loud, on-site alarm is optional. The alarm system may be a silent alarm, providing notification to private security or police without indicating to the burglar that the alarm has been tripped.
Fire alarms are required to be configured to notify the nearest fire department, either directly, or through the fire department’s centralized alarm center.
Burglars want to disable burglar alarms. Arsonists want to disable fire alarms.
The alarm system owner must take care to ensure the physical security of the alarm system. The purpose of this article is to help you understand the issues involved in physically securing alarm systems. This information will help you in establishing design requirements, preparing RFQs, budgeting appropriately, and evaluating systems and system providers.
Two Major System Types
An alarm system (fire or burglar, either one) has three major functional units: (1) the sensors, (2) the control panel, and (3) the notification system.
Ignoring the legal requirements for just a moment, and speaking only from the engineering standpoint, interconnections can be either wired or wireless. The sensors – cameras, microphones, break-glass switches, motion detectors, whatever – can be connected to the control panel with physical wiring, or they can be connected wirelessly via a radio frequency (RF) signal. Likewise – and again, only from an engineering standpoint – the connection to the alarm center (security, police, or fire) can be a wired service provided by the local telephone company, or it can be a wireless service provided by a wireless carrier (a cellular operator).
So we see that the two major system types for alarm systems are (1) wired and (2) wireless. I should mention here that it can be argued that there’s a third system type: (3) hybrid. A hybrid system might use wireless communications between the sensors and the control panel, and wired communications for the notification system.
Legal Requirements
For several years after wireless alarm systems were possible, there were legal requirements in the USA mandating that fire alarms be wired. This originally included both the sensor communications and the notification system communications. In recent years, these laws have been changing. There are now some municipalities that allow wireless sensors to be part of fire alarm systems, and there are some places where the notification system can be connected to a wireless carrier. (Legal disclaimer: I’m not a lawyer. It’s your responsibility to be informed of the laws governing your alarm system at your location).
Wireless Sensor Communications
The majority of modern wireless alarm system sensor communications uses an on-premise Wi-Fi system. Up through Wi-Fi 6, the RF bands used are in the 2.4 GHz and 5 GHz spectrum. Wi-Fi 6E, Wi-Fi 7, and newer standards also use higher frequencies. In the USA, the newest band is from 5.295 GHz to 7.125 GHz.
The bad news is that all of these frequencies can be jammed. In other words, a criminal can disrupt communications between the sensors and the control panel in such a way that the control panel can’t tell if a sensor is reporting a problem. The difficulty for the criminal is knowing which band to jam – or they can just jam all of them.
SOLUTION: Use at least some wired sensors in your alarm system. For example, the window and door sensors might be wired, while the motion detectors are wireless, or vice versa. Or put wired pressure mats in front of the safe and cash registers. Look at what can be easily and inexpensively wired, and wire it. Use wireless connectivity only when necessary, or where a wired connection would cost substantially more.
Wireless Notification System Communications
Before we consider wireless notification systems, let’s take a brief detour and discuss wired notification systems. I’ve already mentioned that, in the USA, some places may still require the use of a wired connection between the control panel and the alarm monitoring center, especially in the case of fire alarms. There may also be some cities, especially smaller ones, where the police station only has the ability to accept wired connections from burglar alarms.
Wired notification systems are on the decline, in part because some telcos are struggling financially to justify the expense of maintaining older copper infrastructure. As a work-around, these telcos are running fiber optic cable to the building (or the nearest utility pole), and converting to copper for the final connection. (Oddly, the telco can use microwave radio systems to carry fire alarm signals back to the Central Office, but the final connection to the business must be wired).
I’m personally aware of a business in the Greater Seattle Metropolitan Area that was unable to get a wired circuit repaired by the telco when it failed. They were forced to purchase a new alarm system with a wireless module, and now their fire alarm notification system is via a cellular carrier. It’s legal in their locale.
Most wireless notification systems use a cellular phone company connection. In the USA, there are several different bands used for wireless telecommunications. Originally it was all in the 800 MHz band, then came 1900 MHz, and now there are a few others.
The bad news, again, is that all of these frequencies can be jammed. It’s generally more difficult than jamming Wi-Fi signals, for a couple of reasons: (1) there’s a lot more spectrum for mobile telecommunications, and the criminal either has to know what system you’re using, or else jam everything, and (2) generally, a cellular jammer requires higher transmitter power than a Wi-Fi jammer. But it can be done, and it can be done with equipment small enough to fit inconspicuously in a car or van.
SOLUTION #1: Use a wired notification system. This can be a telephone voice circuit, a telephone data circuit, a cable Internet circuit, or a fiber optic circuit. For any of these “wired” systems, the cable must be protected at the entrance to the building.
(1) The cable may come in high, at the roof of the building and out of the criminal’s easy reach.
(2) The cable may enter the building from underground, directly into the telecom switch room.
(3) The cable may be “armored,” or shielded, with conduit or pipe.
SOLUTION #2: Use redundant notification systems, one wired and one wireless. In companies with high-availability (HA) Internet service, this configuration often exists already. The primary Internet service may be high bandwidth fiber, and the backup Internet may be a lower bandwidth connection through the cellular carrier, intended for critical services during a failure of the primary circuit.
SOLUTION #3: Recall the scenario I described earlier, where a business lost its copper connection, and the telco wouldn’t repair the copper, and there was no fiber in the area. For businesses like this, no wired option is available. In such cases, I recommend redundancy with two different cellular carriers. Technically, both signals can be jammed, but the likelihood of a criminal having that kind of electronic capability is relatively small. We do what we can, remembering that no system is perfect.
Other Considerations
For the sake of completeness, it’s important to remember that there are many other ways for the criminal to disable your alarm system. They can obtain an employee’s disarm code, create an extended power failure and wait for the backup batteries to discharge, destroy one or more sensors, destroy the control panel… each system has its own vulnerabilities. This article is focused solely on the topic of physical security with regard to the two communications systems: (1) sensor to control panel, and (2) notification system to alarm center.
When using wired communications, the wires can be cut.
When using wireless communications, the RF signals can be jammed.
The most robust system uses wiring that is armored and concealed, in conjunction with wireless components that can’t be approached without triggering another sensor.
Use a multi-layered approach to maximize the physical security of your alarm systems.
With these considerations in mind, you’re better prepared to create your design requirements, write an RFQ, and start evaluating those quotes.
–Bob Young
February 20, 2024