86 standards-based electrical engineering tools, organized into 11 categories. Jump to a category or scroll through all of them below.
IEC 60909 fault currents at every bus of a network with an auto-generated single-line diagram, IEEE 1584-2018 arc-flash studies with labels and PPE, plus quick fault-level estimates and switchgear short-circuit rating checks.
Build a network of buses, utility sources, generators, motors, transformers, cables and ties; get Ik″, peak, breaking, thermal and earth-fault currents at every bus on an auto-generated single-line diagram, with step-by-step working.
Open calculator →Network arc-flash study: incident energy, boundary and PPE category at every bus on a colour-coded single-line diagram, with boundary and energy graphs, maintenance-mode what-if and printable NFPA 70E style labels.
Open calculator →Quick single-point incident energy, arc-flash boundary and PPE category — IEEE 1584-2002, the full IEEE 1584-2018 model and Ralph Lee.
Open calculator →Available fault current at successive points down a radial network using the classic Base kVA Method.
Open calculator →Per-generator and total fault current contribution at a common bus, subtransient-reactance method.
Open calculator →Prospective and peak fault current from transformer kVA/%Z, with OCPD AIC and equipment SCCR adequacy check per NEC 110.9/110.10.
Open calculator →IDMT relay coordination and grading, differential and earth-fault protection, breaker/fuse sizing, and generator paralleling.
The complete protection coordination workbench: time-current curves for IDMT, definite-time, LSIG breakers, MCB, fuses and motors, grading checks, damage curves, 87T/87B/87L, distance, 24/32/46/49/51V, 81/27/59, CT/VT sizing and LV board coordination.
Open calculator →IEC 60255 & IEEE C37.112 inverse-time curves. Add any number of relays to a chain and check full-range grading margin at every step.
Open calculator →Earth-fault IDMT trip time and optional instantaneous stage, reusing the verified IEC 60255-151 / IEEE C37.112 curve engine.
Open calculator →Percentage-bias dual-slope restraint characteristic trip/no-trip check, IEEE C37.91-consistent.
Open calculator →General continuous/non-continuous load OCPD sizing (NEC 210.19/215.2 + 240.4, or IEC 60364-4-43) and motor starting-current withstand sizing (NEC 430.52).
Open calculator →Voltage, frequency and phase-angle synchronization check (ANSI device 25 style) before closing a generator paralleling breaker.
Open calculator →Location-based lookup of NEC 210.12(A) AFCI and 210.8(A) GFCI dwelling-unit protection requirements, with citations.
Open calculator →SPD Type recommendation by location, minimum MCOV from system voltage/grounding, and SCCR check against available fault current.
Open calculator →Cable and conductor sizing, fill and pulling calculations, and overhead/distribution line voltage regulation and losses.
IEC 60364-5-52 current-carrying capacity and voltage drop, with derating, short-circuit withstand, CPC sizing and lifecycle cost as advanced features.
Open calculator →IEC 60287 first-principles thermal-circuit current rating for single-core MV/HV cables, cross-checked against CIGRE TB880.
Open calculator →NEC Chapter 9 Table 1/4/5 (US) or IEC/BS 7671 45%/40% space-factor method (International).
Open calculator →NEC §392.22 width/area rules by tray type & cable category, or the common 40–50% international area-fill practice.
Open calculator →IEEE 1185 tension/capstan equations, sidewall bearing pressure & jam ratio.
Open calculator →HART/4-20mA capacitance-limited maximum cable length, minimum conductor size guidance, and general EMI separation-distance practice.
Open calculator →Voltage drop and regulation from your own conductor R/X per km, current, PF and length.
Open calculator →Annual I²R energy loss estimate from peak load, diversity and load factor, using the loss-factor approximation.
Open calculator →Full NEC Article 310 four-step derating chain — Table 310.16 base ampacity, ambient correction, bundling adjustment, and 110.14(C) termination cap. Auto-size or check a selected conductor.
Open calculator →10-ft, 25-ft and outside unlimited-length feeder tap compliance checks against length, ampacity ratio, protection and terminal OCPD conditions.
Open calculator →Simplified Neher-McGrath / IEC 60287 equal-area equivalent-cylinder external thermal resistance — bank-to-ambient temperature rise or maximum permissible losses.
Open calculator →Open-area (perforation) ratio of a cable tray from width, length and open area, with LOW-HIGH grading.
Open calculator →Earthing grid design, lightning protection and rolling sphere method, touch voltage, and static/ESD hazard checks.
IEEE 80 grid resistance, GPR and tolerable touch/step limits, plus BS 7430 electrode sizing. Mesh/step voltage pass-fail, layered soil and parallel electrodes are advanced features.
Open calculator →IEC 62305-1/2 risk assessment and risk management measures — collection area, structure risk and minimum LPS class. Connected-line risk and SPD/LEMP protection sizing are advanced features.
Open calculator →Single air-terminal protection radius against the IEC 62305 rolling sphere for a given LPS class.
Open calculator →Ground potential rise and touch voltage from an unbalanced neutral/earth current, checked against IEC 60364-4-41 limits.
Open calculator →Hazardous-area bonding/grounding resistance check against the NFPA 77 static-electricity dissipation threshold.
Open calculator →Capacitive discharge spark energy (E=½CV²) vs. atmosphere Minimum Ignition Energy, per IEC 60079-32-1 screening practice.
Open calculator →BS 7430 single-rod resistance-to-earth from soil resistivity and rod geometry, graded against the common 25Ω NEC 250.53(A)(2) practical threshold.
Open calculator →BS 7430 single-ring resistance-to-earth from soil resistivity, ring diameter and burial depth.
Open calculator →Transformer, CT, VT and busbar sizing/rating, plus insulation resistance and polarization index condition tests.
IEC 61869-2 CT ratio, itemized burden and ALF/knee-point voltage check. Saturation analysis, metering class, thermal/mechanical withstand and multi-ratio taps are advanced features.
Open calculator →IEC 61869-3 voltage transformer ratio, voltage factor by earthing system, and burden vs. standard rated outputs. Protection class, thermal limiting output and open-delta residual voltage are advanced features.
Open calculator →Sizes a new transformer (or N-1 redundant group) from connected load, growth/safety margins, ambient derating, and standard ANSI/IEEE kVA ratings.
Open calculator →Genset sizing for running + motor-starting load, and transformer loss/efficiency/regulation from test data. NGR/NET earthing resistor sizing is an advanced feature.
Open calculator →First-principles continuous ampacity and temperature rise for rectangular busbars. Short-time thermal withstand and electrodynamic force check are advanced features.
Open calculator →IEEE 43 kV+1 minimum-IR check with 40°C temperature correction.
Open calculator →PI = IR(10min)/IR(1min) with IEEE 43 condition bands and minimum-PI check by insulation class.
Open calculator →Power factor correction, harmonics, demand studies, voltage/load balance, unit conversion and tariff estimation.
IEC 60831 capacitor bank sizing with current/kVA reduction. Harmonic resonance, detuning reactor sizing and energy-savings analysis are advanced features.
Open calculator →IEEE 519-2014 Table 1 (voltage) & Table 2 (current, TDD-referenced) distortion limit checks. Full per-order breakdown table and K-factor estimate are advanced features.
Open calculator →Load-category demand-factor method with design current and breaker sizing. Multi-board site aggregation & transformer sizing is an advanced feature.
Open calculator →NEMA-style % voltage unbalance and motor derating factor from the NEMA MG1 / ANSI C84.1 curve.
Open calculator →Per-phase load balance and neutral current from the standard 3-phase phasor formula.
Open calculator →Single-phase and three-phase power-triangle and current conversions from a load profile (voltage, power factor, and any one known quantity).
Open calculator →Estimates a monthly electricity bill from itemized time-of-use energy, peak demand charge, fixed charge and an optional power-factor penalty.
Open calculator →Diversity factor and coincident maximum demand for a group of loads on a shared feeder, transformer or panel, with compute and solve-for-unknown modes.
Open calculator →Single-family dwelling service load via NEC Art. 220 Standard Method or 220.82 Optional Method, with recommended minimum service size.
Open calculator →Motor branch-circuit sizing, motor protection, and VFD energy savings.
NEC Article 430 (FLC tables, branch-circuit/OCPD/overload/disconnect sizing) or IEC general method, plus starting-method voltage-dip check.
Open calculator →Overload relay setting & trip class (NEC 430.32 / IEC 60947-4-1), AC-3/AC-4 contactor sizing, and ground-fault pickup guidance by system grounding type.
Open calculator →Affinity-law (power ∝ speed³) energy and cost savings estimate for switching a centrifugal pump/fan from throttled to VFD control.
Open calculator →Steady-state motor or engine shaft torque from output power and operating speed, in N·m or lb-ft.
Open calculator →Time to accelerate a motor-load system from standstill to rated speed, from total inertia and average net accelerating torque.
Open calculator →Screens a candidate soft starter's rated current against motor FLA with temperature/altitude/duty derating, plus voltage check.
Open calculator →Motor nameplate vs VFD rating compatibility screen — voltage match, current loading, base V/Hz ratio, synchronous speed, slip.
Open calculator →Recommends the minimum VFD rated output current from motor FLA, Variable/Constant Torque duty type, and ambient/altitude derating — before you shop for a specific drive.
Open calculator →Battery sizing, UPS sizing, emergency power sequencing, genset fuel, and energy storage (BESS).
IEEE 485 duty-cycle section method for lead-acid battery capacity. Random loads, cell/voltage window checks and charger sizing are advanced features.
Open calculator →Required UPS kVA rating from critical load, margin and redundancy configuration, plus approximate battery energy/Ah for the stated backup time.
Open calculator →NFPA 110 Type/Class classification, UPS-to-genset bridge timing check, and staged load-step pickup planner.
Open calculator →Runtime and hourly cost from tank size and your genset's own fuel consumption rate.
Open calculator →IEEE 1547 / IEC 62933 usable-energy, nameplate capacity, C-rate and PCS voltage-window sizing with AC cable sizing. Multi-bank site aggregation & cycle-life estimate are advanced features.
Open calculator →NEC Art. 700/701/702 automatic/manual transfer switch ampacity from connected load, 125% continuous-load factor, next standard UL 1008 rating.
Open calculator →Check emergency lighting battery runtime against the 90-minute NFPA 101 / NEC 700.12 minimum, or size required Wh and Ah capacity with aging, DoD and inverter efficiency.
Open calculator →Preliminary CHP electrical capacity from electrical and thermal baseload demand and heat-to-power ratio, sized to the more limiting baseload.
Open calculator →Simplified 0-100 Stability Index for islanded microgrid screening from generation headroom, inertia and reserve margin.
Open calculator →BESS power/energy sizing to shave peak demand to a target level, with demand-charge savings and simple payback.
Open calculator →4-20mA loop budgets, intrinsic safety, thermocouple/RTD conversion, and fire & gas loop power.
Loop voltage budget for a 2-wire loop-powered transmitter — wire voltage drop, transmitter headroom, and maximum cable length by AWG.
Open calculator →IEC 60079-11 entity concept — voltage/current/power and capacitance/inductance checks (with the 1% rule) for combining a barrier with IS field apparatus and cable.
Open calculator →NIST ITS-90 thermocouple mV-to-temperature with cold-junction compensation (K/J/T/E), plus IEC 60751 Callendar-Van Dusen RTD conversion with lead-wire compensation.
Open calculator →Standby and alarm-condition voltage budget for a multi-detector fire/gas initiating device circuit with an end-of-line resistor.
Open calculator →Solar PV string/inverter sizing and EV charge point sizing — with room to grow as more renewables tools ship.
IEC 62548 & IEC 60364-7-712 string voltage window, inverter matching, and DC/AC cable sizing. Multi-string parallel arrays with combiner/feeder sizing are an advanced feature.
Open calculator →IEC 61851-1 / 60364-7-722 / 62955 charge point cable, breaker and RCD sizing. Multi-point site demand with load-management diversity is an advanced feature.
Open calculator →Off-grid PWM/MPPT charge controller current rating from array Isc or power/battery voltage, NEC 690.8(A) 125% factor.
Open calculator →Recommended fixed-mount PV tilt angle from site latitude — year-round, two-season, summer- or winter-biased.
Open calculator →Grid-tied DC:AC ratio (ILR) sizing/grading, or off-grid continuous + surge inverter capacity from a connected load.
Open calculator →Electrical power output from rotor diameter, wind speed, air density, power coefficient (Cp) and generator efficiency.
Open calculator →HVAC electrical sizing, lighting design, elevators, data-center PUE, life-cycle cost, and heat management.
Motor-compressor branch-circuit sizing (NEC Art. 440) or IEC general method. Single motor free — multi-motor combination-load & VFD-fed motor are advanced features.
Open calculator →Lumen method (EN 12464-1 or IES Handbook). Interior room types are free — exterior/area lighting and EN 1838 emergency lighting checks are advanced features.
Open calculator →Traction elevator motor power from load/speed/balance/efficiency, plus NEC Table 620.14 feeder demand factor for a group of elevators.
Open calculator →Estimates a traction elevator's annual electrical energy use (kWh/year) from running power, duty cycle, regenerative-drive credit and standby power — structured after ISO 25745-2.
Open calculator →Power Usage Effectiveness (PUE) & DCiE from facility/IT energy, overhead cost, and a Green Grid efficiency-band classification.
Open calculator →Discounted-cash-flow life-cycle cost comparison of two options (e.g. standard vs. premium efficiency) with present worth, equivalent annual cost and simple payback.
Open calculator →Electrical trace-heating power from pipe insulation heat loss, heater cable selection, and circuit voltage-drop/breaker sizing.
Open calculator →Natural-convection heat-dissipation check for panel/MCC enclosures, with IEC 60890-derived forced-air fan sizing if needed.
Open calculator →Items under active consideration for future batches. Not live, not linked — listed here for visibility only.