Key Features

  • 2 x class B NAC output circuit (500mA maximum load per circuit)
  • Designed to meet UL864 10th Edition requirements
  • Built-in synchronization circuitry
  • Each circuit can be programmed as a 24v auxiliary (500mA maximum load per circuit)
  • Extensive front unit status indications


The Velocity Class B Notification Appliance Circuit Module (VL-NCB) provides power for, and handles communications to, the non-addressable notification appliances. 

It has two notification appliance circuits that can be wired in class B configuration. Up to 500mA can be connected to each class B circuit. Each circuit is monitored for open short and earth trouble conditions and will report the status of each circuit back to the Velocity MMP fire alarm control panel. The VL-NCB also has extensive status indications on the front of the unit.

These class B notification modules can be programmed for either unsynchronized bells or synchronised horns/chimes and beacons on each circuit. The VL-NCB can also be programmed as a 24v auxiliary special application class B output, which can be used to provide power to external equipment.

VL-NCB modules are easy to install by simply connecting it to the control panel using an RJ45 cable.


All components in the Velocity range are UL certified and comply with the requirements of Underwriters Laboratories (UL) 864 Control Units and Accessories for Fire Alarm Systems 10th Edition.

Tech Specs

Design StandardUL864 10th Edition
ApprovalUL Laboratories
Circuit typeRegulated 24V DC
Power limited & Supervised
Maximum NAC Current2 x 500mA
Maximum RMS current for a single notification appliance350mA
Maximum Line Impedance3.6Ω (1.8Ω per core)
Wiring Class2 x Class B [Power limited & Supervised]
Special ApplicationsAuxiliary 24V DC Output [Power limited & Unsupervised]
SynchronisationSelectable at each module as:
Sounder (uses synchronisation protocol for horn strobes)
Bell (will pulse the output voltage to give the required temporal pattern)
Operating Temperature0°C (32°F) to 49°C (120°F)
Max Humidity95% Non-Condensing
Dimensions (W x H x D)57mm x 105mm x 47mm
Terminal Wiring Size18 AWG to 14 AWG (0.8mm2 to 2.5mm2)



Velocity Class B Notification Appliance Circuit Module

Velocity Notification Appliance Circuit Module, Class B

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