Know what you are buying
BDA vs DAS vs cell signal booster
Three things get called "the booster" in building management. One is a public safety radio system the fire code requires. One is a cell coverage system for phones. One is a consumer gadget. They have different rules, different permissions and different owners of the airwaves.
The short version
| Public safety BDA (ERRCS) | Cell DAS | Consumer cell signal booster | |
|---|---|---|---|
| What it carries | Fire, police and EMS radio channels | Commercial carrier service for phones | One subscriber's carrier signal |
| Why it exists | Fire code requires coverage for firefighters | Tenants and residents want phone service | Personal use |
| FCC rule | Part 90 signal booster rules (47 CFR 90.219) | Industrial signal booster rules (47 CFR 20.21(c)) | Consumer booster rules (47 CFR 20.21(a)) |
| Whose permission | The public safety frequency license holder | Each carrier whose signals it retransmits | The subscriber's own carrier, plus registration with that carrier |
| Tested by the fire marshal? | Yes, at acceptance and through annual test reports | Only when built as part of a shared public safety system | No |
| Equipment | UL 2524 listed, NEMA-rated cabinets, 12-hour battery | Carrier-approved industrial equipment | Store-bought unit with its own antennas |
| Satisfies the fire code? | Yes, when accepted by the AHJ | Only if built as a shared system that meets the public safety rules | No |
Public safety BDA
This is the system your fire marshal cares about. It retransmits the channels the public safety agency is licensed for, under the FCC's Part 90 rules. A building owner or contractor may operate one only with "the express consent of the licensee(s) of the frequencies for which the device or system is intended to amplify," kept in a recordable format (47 CFR 90.219(b)(1)(i)).
The fire codes add their own requirements: equipment listed to UL 2524 (NFPA 1225 18.12.1.3; IFC 510.4), signal boosters in NEMA 4 or 4X enclosures, batteries in NEMA 3R cabinets (NFPA 1225 18.3.1), 12 hours of backup at full load (NFPA 1225 18.13.2), and supervision through the fire alarm (NFPA 1225 18.14). Wide-band (Class B) units must also be registered with the FCC. See FCC Part 90 registration.
Cell DAS
A distributed antenna system (DAS) is the FCC's term for "a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area or structure" (47 CFR 90.219(a)). In buildings it usually means the system that brings carrier phone service indoors.
An industrial booster used for cell service may be operated by someone who holds an FCC license or "obtains the express consent of the licensee(s) whose frequencies are being retransmitted" (47 CFR 20.21(c)(1)). In practice that means the carriers. NFPA 1225 says the same from the fire side: to enhance any commercial carrier signal, "prior coordination and approval must be obtained from the frequency license holder of those frequencies" (NFPA 1225 A.18.6.1).
Consumer cell signal booster
The boxes sold online for homes and small offices. A subscriber may run one only after getting the consent of their carrier and registering the booster with that carrier, using the approved antennas and cables, on commercial cellular frequencies only (47 CFR 20.21(a)(1) to (4)). They cannot carry public safety radio, so they do nothing for your fire code compliance.
Can they share one system?
Sometimes, and a good design will tell you up front. The rules that apply:
- Public safety comes first. A shared system must keep public safety coverage and performance at the required level "regardless of the amount of traffic carried by the non-public safety services" (NFPA 1225 18.6.3).
- The FCC allows it inside buildings. "In general, signal boosters should utilize the minimum passband that is sufficient to accomplish the purpose. Except for distributed antenna systems (DAS) installed in buildings, the passband of a Class B booster should not encompass both commercial services ... and part 90 Land Mobile and Public Safety Services" (47 CFR 90.219(d)(7)). In other words, a building DAS is the one place a single booster may cover both.
- Both license holders must agree. The public safety design needs approval from the AHJ and the frequency license holder (NFPA 1225 18.2.1), and the carrier side needs the carriers' consent (47 CFR 20.21(c)(1)).
- Nothing may degrade the emergency system. The owner must suspend and correct installations that degrade it (NFPA 1225 18.6.2), and interfering non-public safety systems must be corrected or removed (IFC 510.6.3).
Why this matters for a manager
Two situations to watch for:
- A vendor offers to "fix coverage" for tenants. Ask whether it is a carrier-approved system, which bands it carries, and how it will be kept from interfering with the public safety BDA. Tell your BDA service vendor before anything is installed.
- A resident or tenant installs a consumer booster. It operates on a "secondary, non-interference basis," and if it causes harmful interference, its operator must cooperate and, if necessary, shut it off (47 CFR 20.21(d)). Your fire marshal will expect the building to deal with it.
Not sure whether your building needs a public safety system at all? Check your local rules on ERRCSCheck, and confirm with your fire marshal (AHJ).
Questions people ask
Can a cell phone booster replace our public safety BDA?
No. A consumer signal booster may only work on commercial cellular frequencies (47 CFR 20.21(a)(4)), while the fire code system must carry the public safety channels your fire marshal lists and use equipment listed to UL 2524 (NFPA 1225 18.12.1.3; IFC 510.4).
Can one DAS carry both cell service and fire department radio?
It can, with conditions. NFPA 1225 allows shared infrastructure only if public safety coverage and performance are never degraded "regardless of the amount of traffic carried by the non-public safety services" (18.6.3). FCC rules generally say a Class B booster's passband should not cover both commercial and public safety bands, but make an exception for distributed antenna systems installed in buildings (47 CFR 90.219(d)(7)). Your fire marshal and the frequency license holder still have to approve the design (NFPA 1225 18.2.1).
Our tenants' cell booster is interfering with the fire radio. What now?
The building has to fix it. The model fire code says a non-public safety amplification system that reduces the performance of the emergency system "shall be corrected or removed" (IFC 510.6.3), and FCC rules require booster operators to cooperate and, if necessary, deactivate a booster that causes harmful interference (47 CFR 20.21(d)(2)).
Sources
Primary documents we read for this page. Rules change; confirm with your fire marshal (AHJ).
- 47 CFR 90.219, Use of signal boosters, Electronic Code of Federal Regulations
- 47 CFR 20.21, Signal boosters, Electronic Code of Federal Regulations
- NFPA 1225, Standard for Emergency Services Communications, 2022 Edition: Chapter 18 and section 20.3.10, Georgia Office of Insurance and Safety Fire Commissioner (reproducing NFPA text)
- International Fire Code Section 510, Emergency Responder Communication Coverage, City of Eaton, Ohio (reproducing ICC model code text; edition not stated in the document)
Related
Your building's BDA system, explained for the people who run it
What the BDA in your electrical closet does, what each part is, who else has a say over it, and the five jobs that fall to the building or facilities manager.
FCC registration and licensee consent for your BDA
Which BDAs must be registered with the FCC, what the registration asks for, and why you need the radio licensee's written consent, from FCC primary sources.
BDA and ERRCS glossary
Plain-language definitions of the terms in BDA / ERRCS test reports, permits and vendor quotes, from AHJ to UL 2524, each tied to the code or rule that uses it.