For reliable power distribution, channel a 24VDC supply directly from the main power module to the annunciator hub via a minimum 18AWG shielded pair. Ground the shield at the panel’s main busbar–failure risks induced noise corrupting zone signals. Verify polarity before energizing: red (+), black (-), striped ground.
Zone circuit wiring demands consistency. Use fire-rated twisted pair (FPL or equivalent) for each of the eight supervised loops. Terminate at the control unit’s labeled zone terminals with crimped spade connectors–solder joints introduce contact resistance that triggers false alarms. Cross-check loop resistance: should fall between 30–50 ohms; exceeding 60 ohms mandates recalibration of end-of-line resistors (3.3k ohms 1/2W standard).
Addressable device interconnects follow a strict topology. Daisy-chain detectors and manual stations in a closed loop–never branch circuits, as stubbed connections violate supervision protocols. Maintain a maximum 2,000-foot conductor run per circuit (at 22AWG), recalculating voltage drop for runs beyond 1,500 feet using 2.1% drop per 1,000 ft. For extended coverage, insert a compatible power extender at the midpoint.
NAC (Notification Appliance Circuit) wiring requires separate power sources. Route 16AWG solid copper from dedicated 24VDC aux outputs to strobes and horns, observing polarity and torque specs (15–18 in-lbs). Overlapping NACs with zone wiring causes interference–separate conduits by at least 18 inches, or install metal partitions. For multi-notification circuits, stagger activation times by programming 10-second delays between sequences to prevent battery drain.
RS-485 network integration needs balanced impedance. Terminate the twisted pair at both ends with 120-ohm 1/4W resistors on the last device. Use shielded CAT5e or better for runs exceeding 500 feet, grounding the shield only at the control panel. Avoid parallel runs with AC power lines–minimum 24-inch separation is mandatory. For redundant paths, deploy a second RS-485 pair with mirrored terminations.
Connecting the CMX-2 Fire Alarm Control Panel: Key Guidelines
Begin by identifying the main power terminals on the rear of the unit. Label them L1 (live) and N (neutral) for 230V AC input. Use 1.5 mm² copper conductors, rated for at least 60°C, to handle the 3A load. Secure connections with ring terminals and apply heat-shrink tubing to prevent oxidation. Never twist wires–crimp or solder for reliability.
For battery backup, connect two 12V 7Ah sealed lead-acid batteries in series. Terminals are clearly marked (+) and (-) on the board; use 2.5 mm² cables for minimal voltage drop. Verify polarity with a multimeter before powering on–reversing will damage the charging circuit. Disconnect AC power before connecting batteries to avoid accidental shorts.
Device Loop Configuration
| Loop | Color Code (EU) | Max Devices | Termination Resistor |
|---|---|---|---|
| Loop 1 | Red (1+), Black (1-) | 127 | 4.7kΩ, 0.5W |
| Loop 2 | Yellow (2+), Blue (2-) | 99 | 6.8kΩ, 0.25W |
Attach devices by stripping 6mm of insulation and inserting into the spring-loaded terminals–no tools needed. For long runs (over 200m), use shielded twisted pair (STP) cable to reduce electromagnetic interference. Ground the shield at the panel only, leaving it unterminated at the far end. Avoid daisy-chaining detectors; use Class B (Style 6) wiring for optimal fault tolerance.
Signal cables require separate routing from power lines to prevent induced noise. Maintain a 300mm separation where unavoidable; cross at 90° angles. For exposed installations, use steel conduit or armored cable with earth continuity. Label each conductor at both ends with heat-shrink sleeves or numbered tags matching the schematics–makes troubleshooting faster.
Remote Indicator Connections
Connect remote LEDs via 0.5 mm² cables to the “Alarm” and “Fault” outputs. The panel sources 24V DC; limit current to 20mA per LED. Use a 1kΩ dropping resistor for each 20mA LED. Test with a temporary LED before final installation to confirm correct polarity. For audible indicators, wire a 24V DC piezoelectric buzzer in parallel with the LED, adding a 1N4007 diode across the buzzer to suppress voltage spikes.
Final checks include verifying no loose strands touch adjacent terminals–shorts can trigger false alarms. Power up with AC only first, then connect batteries. Observe the display for “AC Power OK” and “Battery Charging.” If the system beeps intermittently, measure loop voltages with a high-impedance meter: expect 16–24V DC for healthy loops. Log all readings for baseline comparisons during maintenance.
Powering the CMX-2 Fire Alarm Control Unit
Connect the primary 24VDC power input to terminals labeled BAT+ and BAT- on the main control board. Use 18 AWG stranded copper wire for runs under 30 meters; switch to 16 AWG for longer distances to prevent voltage drop. Verify polarity before tightening terminal screws to 0.9 Nm torque–reverse polarity voids the warranty and risks damaging the built-in transient protection. If the system includes redundant power, connect the secondary source to AUX+ and AUX- using identical wire gauge as the primary circuit.
Grounding Requirements
Attach a dedicated #12 AWG solid copper wire from the GND terminal to the facility’s earth ground busbar. Ensure the grounding path measures under 3 ohms resistance; higher values compromise alarm signaling and surge suppression. Avoid daisy-chaining grounds–each unit must have an independent path to the earth point. For installations in high-noise environments, add a ferrite bead on the ground wire near the control panel to filter transient interference.
Connecting Addressable Fire Detection Components to Advanced Control Panels
Use 2-core screened twisted pair cables rated at least 0.8 mm² for loop connections to maintain signal integrity under 24V DC voltage drop limits. Terminate each device with an EOL resistor–typically 4.7 kΩ–placed at the farthest point to ensure proper fault detection; omit resistors at intermediate nodes to avoid false supervision errors. Adhere to Class A (return loop) topology for critical zones to retain full functionality during single-break faults; Class B (stub) suffices for non-essential areas provided redundancy isn’t required.
Program device addresses sequentially starting from 1 to minimize troubleshooting complexity–test each connection with a multimeter set to resistance mode before energizing the system, verifying readings align with expected values:
- Base isolation module: 4.7 kΩ ±5%
- Heat/smoke sensor: infinite (open circuit)
- Sounder/beacon: 1.8 kΩ ±10%
- Manual call point: short (0 Ω)
Confirm polarity inversion (positive to negative) at alternating junctions every 500 meters to counteract capacitance buildup, preserving signal integrity across extended runs. Document exact cable routes and device coordinates in panel configuration software for precise system mapping.
Terminating Notification Appliance Circuits on the CMX-2 Control Panel
Connect NAC loops to the terminal block labeled EOL on the supervisory module, ensuring polarity matches the appliance specifications. For Class B (Style B) circuits, wire the end-of-line resistor (EOLR) between the last device’s return terminal and the control unit’s negative terminal, using 4.7kΩ ±5% for 24VDC or 10kΩ ±5% for 12VDC. Verify continuity with a multimeter–readings should stabilize at half the supply voltage under normal conditions. Deviations indicate faults: stray resistance <1kΩ suggests a short, while >20kΩ signals an open circuit.
Grounding requirements differ by jurisdiction: NFPA 72 (US) mandates a dedicated earth ground for NACs exceeding 1A, while EN 54-13 (EU) enforces a maximum loop resistance of 50Ω. Use 14 AWG solid copper for runs under 300m and 12 AWG for longer distances, applying crimp connectors with heat-shrink tubing to prevent corrosion. Never daisy-chain more than 30 devices on a single loop without recalculating voltage drop–use the panel’s built-in circuit calculator or Ohm’s law: Vdrop = I × Rwire.
For redundant loops (Class A), split the circuit at the control module using SPDT relays or the panel’s built-in redundancy terminals. Wire the first leg normally, then route the second leg through reverse polarity–this ensures failover detection within 10 seconds of a break. Test the failover by disconnecting a middle device: the panel should log a trouble event (not a fault) and switch to the backup path without alarm activation. Avoid mixing strobes and horns on the same loop–strobes demand higher inrush current, risking nuisance alarms.
Label every conductor at both ends: NAC1 (+), NAC1 (-), NAC1 EOL. Use white for positive, black for negative, and red for EOL on Class B; invert colors for Class A to match the panel’s internal diagram. Secure all terminations with star washers to prevent loosening from vibration–particularly in industrial environments. Update the panel’s loop resistance table via its configuration software after any wiring change; default values often underestimate real-world conditions.
For high-power appliances (e.g., 15W horns), add a separate power supply rather than overloading the NAC. Wire the auxiliary supply in parallel with the loop, but route its negative return to the isolated ground bus–never the NAC’s common. Document the exact resistance per meter of your chosen cable type (e.g., 0.0088Ω/m for 14 AWG) and calculate total loop resistance before commissioning. Keep a spare EOL resistor taped to the panel door for field replacements–wrong values void supervision.