Electrical Engineering
Calculators
Free, browser-based tools for quick calculations: NEC and IEC methods, no download required. For full workflow automation, see the Tools & Products page.
Cable Ampacity Derating
NEC Table 310.16 base ampacity with temperature correction and grouping factors. IEC 60364-5-52 reference.
Open Calculator →Cable Tray Fill Calculator
Area-fill method for ladder/ventilated trough (50%) and solid-bottom tray (40%) per NEC Article 392. Instant pass/fail.
Open Calculator →Conduit Fill Calculator
NEC Chapter 9 Table 1 fill limits. EMT, IMC, RMC, PVC, HDPE. Instant pass/fail and upsize recommendations.
Open Calculator →Demand Load Calculator
Add load groups with individual demand factors. Apply diversity factor and design margin. Outputs kW and kVA for equipment sizing.
Open Calculator →Duct Bank Sizing Calculator
Envelope dimensions, concrete volume, and burial depth reference from conduit rows/columns and spacing. NEC and IEC.
Open Calculator →Ground Grid Resistance Calculator
Grid resistance, ground potential rise, and touch/step voltage screening check: IEEE 80 simplified method.
Open Calculator →Motor Power Calculator
Rated Output or Absorbed Load input mode. Full load current, LRA, kW/kVAR/kVA. NEC Art. 430 and IEC 60034.
Open Calculator →Short Circuit Current (MVA Method)
Three-phase, line-to-line, and line-to-ground fault currents at transformer secondary or end of cable run.
Open Calculator →Transformer Sizing and Inrush
Size a transformer from design load, growth, and derating, then check fault current, inrush check points, regulation, and primary protection. NEC and IEC.
Open Calculator →Generator Sizing and Step Load
Size a generator set for steady load plus the largest motor start: starting kVA by method, voltage dip from X"d, paralleling and N+1, and standard set size.
Open Calculator →Voltage Drop Calculator
Single-phase and three-phase. Equipment rating → derived current. NEC Art. 210/215 and IEC 60364-5-52. Max length outputs.
Open Calculator →