Just about every two weeks we get a call from a builder or developer telling us they would like our services in checking an existing DAS system that has not passed inspections for a long time and the installer is unable to finish it. A few minutes into the conversation, we have confirmation once again that the DAS system was installed by a Fire Safety vendor.

Builders cannot be entirely faulted for thinking that a fire safety vendor is well-suited to the task of providing a DAS system. After all, requirements for both systems are enshrined within California Fire code and that probably is true across the nation. However, the underlying technology for a DAS system is entirely a different science: it requires understanding radio signals and how each band of frequencies behaves; it requires complex math in understanding of device outputs & values; and it requires understanding of signal loss and specific techniques to avoid it.   Most importantly, it requires exotic gear to be able to test and measure outputs to ensure provided signal is not only enough but also not beyond required levels, because in either case of too much signal output or too little there are liabilities for all involved.  A well-equipped, genuine DAS vendor may in fact be using devices costing tens of thousands of dollars to test a DAS system.  Moreover, both the designer of such a system and its installer are required by code to own FCC licenses (Grol license) as well as certification from the manufacturer of radios used in DAS systems.

The simple analogy to help understand the above distinction is this: you would not hire a Fire Safety vendor to provide you with a Commercial WiFi system: a WiFi system conceptually is similar to a DAS system because in both cases a specific signal for communication is acquired (Internet service for WiFi or Radio Signal from Fire Department in a DAS system) and are broadcast across areas where connectivity for communication is required.  And yet, for all the important reasons below, you would have far less liability if you were to have a Fire Safety Vendor install a WiFi system for you rather than a DAS system:

1. Degree of coverage by a WiFi system is not as critical and is not specifically mandated: for a DAS system, by code all common area of a building need to have 95 percent coverage and critical pathways need to have 99 percent coverage; otherwise you will not pass inspection. In some AHJ, Pasadena, Glendale, Culver City, West Hollywood and adjacent communities, for example, very knowledgeable third party inspectors will test a DAS system and verify extent and strength of coverage.
2. WiFi systems universally receive the same signal to connect to the web and behave the same way regardless of their performance level; whereas frequencies used by a DAS system vary from city to city and different frequencies have entirely different propagation properties with anomalies associated with specific bands. An installer has to understand behavior of different bands and work around limitations and anomalies each band represents. This means understanding radio science.
3. Most importantly, too much signal is NOT an issue in a WiFi system. If WiFi signal extends beyond your building, it will not have much/any impact on WiFi in a neighboring property.  When looking for WiFi signal, we all frequently see multiple WiFi options with strength present in the same location. A DAS system leaking signal out of your building is in violation of FCC, State and City statutes because frequencies used for DAS systems travel far and can be acquired by another building’s DAS antenna, causing various forms of failure in other DAS systems.  There is a $30K penalty levied by the FCC if it were to discover that a DAS system in your building is leaking signal to nearby areas.

So far, Fire Safety vendors in the city of Los Angeles have been able to pass inspections by propagating too much signal to ensure passing their inspection.  An LA fire inspector is not an engineer and he is equipped with only a radio for his final inspection.  If he sees good connection with the Fire Dept HQ, he is satisfied there is adequate signal & pass the vendor in that inspection; what he cannot know is that the same DAS system is pushing that signal hundreds of feet away also.  Therefore, the third bullet point above merits a much longer discussion, but at a minimum you need to realize that an improperly installed DAS (ERRCS) installed in your can have a disabling effect on the DAS systems nearby and/or on the entire city- or county-wide radio network in a variety of ways too technical to detail here. By putting plenty of signal through his system in your building, a Fire Safety DAS vendor will pass inspection conducted within the building, but the signal leaking outside the building may prevent fire department officers showing up in a nearby building from connecting to their base and exchanging critically important messages.

Moreover, that signal leakage may not be discovered for some time because currently too few buildings exist with a DAS system since the mandate is fairly new.  However, as soon another building is erected nearby, the second DAS system will have either too much noise in the system or no capacity to communicate despite its DAS vendor’s correct deployment.  The second DAS vendor will eventually figure out that the problem in their system is signal leakage from a nearby building and a casual look in the neighborhood will identify the building with the offending DAS system; he will have no choice but to inform the agencies involved because he cannot pass inspection on his system as long as the DAS system in your building is active and is leaking signal.

That discovery point may be one or two years away from the time your Fire Safety vendor has passed inspection in your project, but as more DAS systems are deployed in the area, it will eventually come. We will put aside all other liabilities when that moment of discovery comes, but consider that at a minimum fixing the offending DAS systems’ output is a very large undertaking.  Few competent DAS vendors are willing to undertake the task of correcting such a DAS system because they have to provide you with only extensive labor to redesign and/or troubleshoot the system and limit signal to what is required.

Currently most cities are using a third party inspector to test performance of these DAS systems exactly for all the above reasons.  These inspectors will first verify if the installer is actually properly licensed and secondly if the system deployed is working properly.  In fact, most AHJ, other than City of LA and Santa Monica, are requiring to see a design submission to verify credentials of the installer.  That safety measure still does NOT exist in the city of LA and therefore Fire Safety vendors who do not understand radio science are able to get systems sold and deployed in the City of LA. They are able to beat estimates from the more experienced and knowledgeable DAS installers since they are doing both Fire Safety and DAS system; they may often pass inspection by flooding the building with too much signal; but in the end, the unknown issues they leave behind will be a liability awaiting eventual discovery in what is a life safety system and regulated by all levels of government.