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Fire Alarm Calculators
Use the same core methods registered in Fire Regs Pro. Every result exposes its assumptions and source context.
Standby Battery Size minimum new battery capacity Combine standby and alarm loads with ageing and alarm-current derating. Sound Level Estimate SPL at the listening point Apply free-field attenuation and compare with a selected alarm requirement. Detector Spacing Estimate a rectangular detector grid Use radial coverage for smoke or heat detectors and a pitched-ceiling allowance. Cable Voltage Drop Check end-of-line voltage Estimate copper loop resistance, voltage drop and device voltage at the circuit end. Circuit Loading Find the lower device-count limit Compare the panel-output and worst-case end-of-line voltage-drop constraints. Ohm's Law Solve voltage, current, resistance and power Enter any two electrical quantities to calculate the remaining pair.
Design aid, not sign-off. These tools mirror the app formulas but cannot account for every building, manufacturer instruction, environmental condition or clause exception. Verify inputs, current documents and on-site measurements.