Engineering tools
Electrical engineering tools
Calculators for cable sizing and short-circuit withstand, voltage drop, wire gauges, power and current, power factor correction, motor starters, transformer sizing and fault current, earth electrodes and lighting by the lumen method, with the formulas and limits behind them.
Low-voltage installation tools for engineers, electricians and technically minded owners. Results are computed from the stated formula and assumptions; always confirm against the standard that applies to your installation.
Voltage drop calculator
Calculate voltage drop and percentage drop for DC, single-phase and three-phase circuits from cable length, current, conductor size and material, and find the smallest conductor that meets your limit.
Open tool →Cable sizing calculator
Choose a copper conductor size to IEC 60364-5-52 from the design current and breaker rating, the installation method, PVC or XLPE insulation, ambient temperature and grouping, with the Ib ≤ In ≤ Iz coordination and the voltage drop over the route checked together.
Open tool →Cable short-circuit withstand calculator
Check a conductor against the adiabatic equation of IEC 60364-4-43: the fault I²t, the smallest size that survives it, what your chosen size can absorb, the longest clearing time and the largest current it tolerates, for copper or aluminium, PVC or XLPE, line or protective conductors.
Open tool →Wire gauge converter (AWG, mm², diameter)
Convert an AWG number, a cross-section in mm² or a measured diameter into the other two, find the nearest and next-up IEC 60228 size, and get the resistance per kilometre at any temperature, the resistance of a run and its loop, and the mass of copper or aluminium. With an SWG and 7/029 table.
Open tool →Power and current calculator
Convert between kW, kVA and amperes for DC, single-phase and three-phase circuits, with power factor and motor efficiency taken into account, and see the reactive power and phase angle that go with them.
Open tool →Motor starter sizing calculator
Find a motor's full-load current from its nameplate data, compare the starting current and torque of direct-on-line, star-delta, soft starter and drive, then pick the AC-3 contactor, the overload relay setting, the short-circuit device and the cable design current for the method you choose.
Open tool →Power factor correction calculator
Work out the capacitor bank (kVAr) needed to raise a load's power factor to a target, the capacitance per phase for delta or star connection, and how much the apparent power and line current fall as a result.
Open tool →Transformer sizing and fault current calculator
Size a distribution transformer from the connected load, demand factor, power factor, growth and planned loading, pick the next IEC 60076 standard kVA, and get the full-load currents on both sides and the short-circuit current at the LV terminals from the percent impedance.
Open tool →Lighting calculator (lumen method)
Work out how many luminaires a room needs for a target maintained illuminance with the lumen method: room index, utilisation and maintenance factors, a rectangular grid with its spacing-to-height ratio, the lux that grid achieves, and the lighting power density in W/m².
Open tool →Earth electrode resistance calculator
Estimate the resistance to earth of a driven rod from the soil resistivity, its length and diameter, see what more rods in a line, a longer rod or better soil would do, find how many rods a target needs, and check the TT touch-voltage limit for the RCD you use.
Open tool →Reading the results
Voltage drop limits differ by standard and by load type. Lighting circuits are commonly held to a tighter limit than power circuits, and a long feeder plus a long final circuit must be assessed together. The tools state which limit they compare against; the linked guides explain where those limits come from.