Engineering Tool Kit
Free Technical Calculators for BS 7671 Compliance
All-in-One Circuit Designer
Complete BS 7671 design engine. Calculate cable sizes, protective devices, voltage drop, and diversity for lighting, power, and ring final circuits.
Max Demand & Diversity
The ultimate engine for assessing Maximum Demand. Supports Single/Three Phase, Commercial Kitchen logic (OSG Table A2), and Usage Factors.
Circuit Protection Selector
Calculate Ib and automatically select correct MCB, RCBO, or Fuse ratings. Includes Type B, C, and D trip curve guidance for BS 7671 compliance.
Cable Sizing Suite
BS 7671 compliant calculator. Automatically size multicore cables based on Design Current (Ib), Voltage Drop, and Installation Methods.
Maximum Zs Values
Find 100% and 80% Earth Fault Loop Impedance limits for MCBs, RCBOs, Fuses, and MCCBs from leading brands.
Fault Current (PFC)
Instantly calculate Prospective Fault Current (PSCC & PEFC) in Amps and kA for Single and Three-Phase systems.
Ring Continuity (R1+R2)
Verify dead test readings. Calculate r1, r2, and R1+R2, or reverse-engineer continuity from live Zs and Ze measurements.
Containment Fill
Calculate cable capacities and minimum containment sizes to ensure compliance with the BS 7671 space factor rules.
LED ROI Calculator
Calculate commercial lighting return on investment (ROI), annual financial savings, and carbon footprint reduction.
Ohm's Law & Power
Enter any two known values to instantly calculate Voltage (V), Current (A), Resistance (Ω), and Power (W).