Engineering
Calculators

Engineering calculators for battery standby, cable sizing, detector spacing, PoE budgets and more.

Fire Alarm Calculators
BS 5839-1 compliant calculations for fire detection system design and commissioning.
Fire / Intruder
Battery Standby
Calculate required battery capacity per BS 5839-1 / BS EN 50131
Minimum Battery Capacity
—
Ah (Amp-hours)
Fire Alarm
Detector Spacing
BS 5839-1 maximum detector coverage areas and spacing
Minimum Detectors Required
—
detectors
Fire Alarm
Sounder Circuit Loading
Calculate total sounder/VAD current draw on a circuit
Total Circuit Current
—
mA (milliamps)
Fire Alarm / General
Cable CSA Sizing
Select minimum conductor cross-sectional area for a cable run
Minimum Cable CSA
—
mm²
Fire Alarm
Coverage Area
Calculate how many detectors cover a given floor area
Detectors Required
—
detectors (minimum)
Fire Alarm — Conventional
Zone Resistance
Calculate total zone circuit resistance including EOL resistor
Total Zone Circuit Resistance
—
Ω (Ohms)
CCTV & Network Calculators
Storage, bandwidth, and power calculations for IP CCTV and network security systems.
CCTV
CCTV Storage
Calculate HDD/NVR storage required for your CCTV system
Required Storage
—
TB (Terabytes)
CCTV / Access
PoE Budget
Check if your PoE switch can power all connected devices
Total PoE Load
—
Watts
Fire Alarm — Addressable
Cable Capacitance
Check loop cable capacitance against panel maximums
Total Loop Capacitance
—
nF (nanofarads)
General & Electrical Calculators
Voltage drop, loop resistance, and cable calculations for all security disciplines.
General
Voltage Drop
Calculate voltage drop along a DC cable run
Voltage Drop
—
V (Volts)
Intruder Alarm
Loop Resistance
Calculate zone loop resistance from cable length and CSA
Total Loop Resistance
—
Ω (Ohms) — round trip
Fire / Intruder
Standby Duration
How long will a given battery last at a known quiescent load?
Standby Duration
—
hours