BS 7671 Electrical Calculators
Free online calculators for electrical installation design, testing, and verification to BS 7671 standards.
Ohm's Law / Power Calculator
Calculate voltage, current, resistance, and power using Ohm's Law and the power triangle. Essential for every electrician.
FoundationalCable Sizing Calculator
Determine the correct cable size based on load current, installation method, and grouping factors per BS 7671.
BS 7671Voltage Drop Calculator
Calculate voltage drop across cable runs and verify compliance with BS 7671 Table 4D1B limits.
Table 4D1BProspective Fault Current
Calculate prospective fault current (PFC) to ensure protective devices can safely interrupt fault conditions.
BS 7671R1+R2 Calculator
Calculate earth fault loop impedance from R1+R2 measurements using BS 7671 Table I1 conductor resistance values.
Table I1Adiabatic Equation
Calculate minimum CPC size using the adiabatic equation from BS 7671 Table 54.4 for fault current protection.
Table 54.4EV Charger Installation
Plan EV charger installations with load calculations, cable sizing, and earthing requirements per Section 722.
Section 722Solar PV / DC Sizing
Calculate DC cable sizing, string voltage, and inverter matching for solar PV installations per Section 712.
Section 712Conduit & Trunking Fill
Calculate conduit and trunking fill capacity to ensure cables are not overcrowded per BS 7671 requirements.
BS 7671IP Rating & Zones
Look up IP ratings and determine appropriate equipment ratings for bathroom and special location zones.
Section 701