Electrical Installations

Electrical installation calculators and formulas for wiring, voltage drop, protection sizing, and earthing. Covers cable sizing, voltage drop percentage, and circuit breaker rating calculations.

9Formulas

All levels Difficulty

Updated Jul 2026

← All Electrical Engineering (151) Electrical Installations (9)

Fundamental

Lux & Lumens Calculator

Lumens = Lux × Area (m²) · Lux = f( Activity )

Fundamental

Cable Ampacity Derating Factor

I_derated = I_rated × k₁ × k₂

Fundamental

Earthing Resistance (Rod Electrode)

R = ρ / (2π·L)

Fundamental

Power Loss Percentage

%Loss = (P_loss / P_input) × 100

Fundamental

Circuit Breaker Sizing with Safety Margin

I_breaker = (P / (V × cos θ)) × 1.25

Fundamental

Fuse/Breaker Current Rating

I_rating = P / V

Fundamental

Wire Resistance from Resistivity

R = ρ·L / A

Fundamental

Percentage Voltage Drop

%VD = (V_d / V_rated) × 100

Fundamental

Cable Voltage Drop (Single Phase)

V_d = (2 × L × I × R) / 1000