Free Electrical Calculators & Reference Tables
Calculators
Check voltage drop on any circuit run. Single-phase, three-phase, and DC with copper or aluminum conductors.
Use Tool →Determine minimum conductor size per NEC 310.16 ampacity tables with automatic voltage drop verification.
Use Tool →Calculate conduit fill percentage per NEC Chapter 9 tables. Supports EMT, IMC, RMC, PVC, and FMC with multiple wire types.
Use Tool →Calculate required box volume in cubic inches per NEC 314.16. Counts conductors, devices, clamps, and equipment grounds.
Use Tool →Single-family dwelling load calculation per NEC Article 220. Standard method (Part III) and optional method (Part IV).
Use Tool →Size standby generators with load management calculations and Generac model recommendations.
Use Tool →Complete circuit design from panel to last outlet. Combines feeder and branch voltage drop, wire sizing, derating, and EGC in one calculation.
Use Tool →Enter any two of voltage, current, resistance, or power and instantly calculate the rest. Quick reference for the field.
Use Tool →Calculate bending multipliers, shrink, and distances for offsets, saddles, kicks, and 90-degree bends. EMT, IMC, and RMC.
Use Tool →Convert between kW, kVA, amps, HP, and watts for single-phase, three-phase, and DC circuits.
Use Tool →Printable cheat sheet with Ohm's Law, single and three-phase power, motor, transformer, and NEC quick rules.
View Sheet →Calculate kVA rating, primary and secondary full-load amps, and recommended standard transformer sizes.
Use Tool →Apply temperature correction and conduit fill adjustment factors to NEC 310.16 base ampacity values.
Use Tool →Reference Tables
Full-load current for single-phase and three-phase motors. Use for conductor and overcurrent sizing.
View Table →Allowable ampacities at 60°C, 75°C, and 90°C for copper and aluminum conductors.
View Table →Max breaker/fuse size by conductor gauge. The table apprentices need for exams.
View Table →How many THHN/THWN wires fit in each conduit size. EMT, IMC, and RMC.
View Table →Equipment grounding conductor sizing by overcurrent device rating. Copper and aluminum.
View Table →Torque values by lug type and wire size. Common values for mechanical and compression connectors.
View Table →Resistance, area, and diameter for all conductor sizes. The data behind voltage drop calculations.
View Table →