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Bi-Directional Amplifiers (BDAs)
The Code-Driven Life Saving Technology You Need to Know

By Derek Case

Fifty six percent of fire departments experienced a communications failure in a building during an emergency event, according to a 2017 International Association of Fire Chiefs (IAFC) survey by the Safer Buildings Coalition. Because many buildings lack reliable radio signal coverage, fire fighters and other first responders often lose communications in buildings, leaving them virtually stranded in emergency situations.

What is BDA

Bi-directional amplifiers (BDAs) reduce communications failures by amplifing wireless communications signals within a building. BDAs also corrects radio coverage dead spots so there is always two-way communication from a first responder to fireground operations. These systems are also known in the industry as Emergency Responder Radios Enhancement Systems (ERRES).

Codes Requirements

Code development activities were accelerated after the terrorist attacks that occurred on September 11, 2001, when first responders required open communication channels for emergency operations. For example, this technology first appeared in the 2007 edition of the NFPA 72®, National Fire Alarm Code.1  Section 6.10.2 of NFPA 72 permitted, did not require, the installation of two-way in-building radio communications enhancement systems and permitted these systems to be monitored by the building fire alarm system. For the 2016 edition of NFPA 72, the design and installation requirements were relocated to the 2016 edition of NFPA 1221, Standard for the Installation, Maintenance, and Use of Emergency Services Communications Systems.2

In the 2009 edition of the International Fire Code (IFC),3  a new section was added that required all buildings to have approved radio coverage for emergency responders within buildings. As defined in the IFC, “Approved” is a defined as a means acceptable to the fire code official. Although BDA systems were mandated to be installed; no requirements were in the body of the code for designing, installing, testing and maintaining an ERRES. Instead Appendix J provided the technical guidance. The provisions of Appendix J are not mandatory unless specifically referenced in an adopting ordinance. For the 2012 edition of the IFC, the provisions for designing, installing, testing and maintaining an ERRES were moved from Appendix J into Section 510 of the Code.

Since the 2012 edition of the IFC, installation requirements and expectations for communication amplifiers have become more prescriptive about the technology. In 2018, the latest IFC standard, Section 510 addresses emergency responder radio coverage. It says:

“All new buildings shall have approved radio coverage for emergency responders within the building based upon the existing coverage levels of the public safety communication systems of the jurisdiction at the exterior of the building…Existing buildings shall be provided with approved radio coverage for emergency responders as required in Chapter 11.”

Specifically, buildings need to have at least 95 percent coverage in all general areas of each floor of a building and 99% of all critical areas in order to be considered compliant with IFC standards. Buildings that do not have the required signal levels require amplification systems.

Additionally, the 2009 edition of the International Building Code (IBC) adopted a position on BDAs, stating emergency responder radio coverage must be present in all new buildings in accordance with Section 510 of the IFC.

Emergency response radio coverage systems must be designed in accordance with IFC sections 510.4.2.1 through 510.4.2.5. The 2016 edition of NFPA 1221 outlines specific guidelines for engineers looking to design BDA systems.

Technical Aspects

BDAs provide an in-building radio signal amplification, giving commercial buildings ~100% coverage for public safety agencies. Full BDA systems are generally composed of eight parts, which are illustrated in Figure 1:

  • Donor antenna: Installed on the roof of a building, it points to the public safety radio repeater site.
  • Coaxial Cable: Most often, a plenum rated cable.
  • BDA: The signal booster, which must meet requirements of the local authority having jurisdiction (each jurisdiction is different).
  • Signal Splitters and Couplers: These are used for signal distribution.
  • RF Connectors: Must be installed using a specialized tool, but easily done by a trained technician.
  • Distributed Antenna System (DAS) Antennas
  • Battery Backup
  • Annunciator Panel

Designing BDA Systems

So how can the industry ensure new buildings are compliant with future requirements? These are six steps engineers and architects should take when designing a BDA system:

  1. Review their AHJ requirements, specifically
    1. Frequencies that are involved or must be met
    2. Code compliance
    3. Special installation requirements
    4. Permitting, submittals, testing and service requirements
  2. Review the engineering requirements
    1. Special technical requirements (for example: extra battery backup or equipment add-ons)
    2. Documentation and submittal requirements
    3. Listing and other compliance requirements
  3. When the building is substantially complete
    1. Perform initial RF coverage survey to determine where coverage enhancement is required
    2. Determine optimal equipment location, fire-rated spaces and cable paths
    3. Submit survey results to the BDA system design engineer
  4. Engineering designs system based on the information provided in steps above
    1. Submit the system design drawings and documents for approval
      1. First, send to A&E to review for code-compliance and fire survivability requirements and approval
      2. Next, submit to AHJ for review and approval
      3. Once approved, submit to electrical contractor for cable and electrical equipment installation
    2. The design process is complete
      1. System installation, final testing and acceptance

    BDA technology is easily installed in buildings where architects have designed a building with 2-hour rated risers and other provisions to support such systems. However, in states or municipalities that require BDA technology, systems also can be retrofitted into existing buildings.

    Property owners of existing buildings must also be aware of BDA requirements from the IFC. Smaller buildings may already have sufficient radio signal coverage levels. To determine if a small building does have adequate coverage levels, property owners must provide a signal survey report documenting the existing signal levels. In the United States, these surveys must be performed and signed by a qualified, Federal Communications General Radiotelephone Operator Licensed (FCC-GROL) vendor. Property owners then submit the survey for review and verification to the authority having jurisdiction.

    Florida has taken additional steps to include BDAs in new buildings that are an example of the trend toward including communication amplifying technology. Starting in 2019, the state recently adopted legislation requiring every commercial building to complete a radio signal strength survey to make sure the buildings are compliant with the current edition of the IFC. If found not compliant, these buildings have until January 2022 to install a BDA system. 

    Derek Case is with Honeywell Fire Safety.

    References

    1NFPA 72®, National Fire Alarm Code. (2007). National Fire Protection Association. Quincy, MA.

    2NFPA 1221, Standard for the Installation, Maintenance, and Use of Emergency Services Communications Systems. (2016). National Fire Protection Association. Quincy, MA.

    3International Fire Code (IFC). (2009). International Code Council. Washington, DC.