Electrical

Electrical calculators for electricians, engineers and installers — Ohm’s law and the power wheel, cable voltage drop, conductor size and ampacity, circuit load and breaker sizing, running energy cost, transformer sizing and fault level, motor full-load current and protection, power factor correction, and a job estimator. Metric (mm² / IEC) and imperial (AWG / NEC) units throughout.

• Ohm's Law & PowerThe V·I·R·P wheel — enter any two of voltage, current, resistance and power and get the other two — plus DC,…
• Voltage DropWork out the voltage drop over a cable run — volts lost, drop as a percentage, the voltage left at the load,…
• Wire Size & AmpacityConvert conductor sizes between AWG/kcmil and mm², apply ambient-temperature and grouping derating to a…
• Circuit Load & Breaker SizeList the loads on a circuit or distribution board with their quantities and demand factors, and get the…
• Energy CostWork out what an appliance or circuit really costs to run — from its power rating and hours of use, from two…
• Transformer Sizing & RatioFull-load current on both sides of a transformer, the turns ratio including the delta/star √3 caveat, and the…
• Electrical Job EstimatorA split-screen pricing sheet for a site visit — quantity takeoff, a routing-environment labour multiplier and…
• Motor Full-Load CurrentFull-load current from a motor nameplate for DC, single- and three-phase supplies, with the NEC table value…
• Power Factor & CorrectionSolve the power triangle from any two of kW, kVA, kVAr and power factor, then size a correction capacitor…
• Lighting — Lux & LumensThe lumen method in three parts: how many lumens and luminaires a target illuminance demands, what an…