Electricity calculator group

Wiring and Protection Calculators

Estimate conductor resistance, losses, enclosure fill, fault quantities, and protective-device loading.

Separate arithmetic from installation rules

These pages estimate resistance, loss, current sharing, fill, fault quantities, and preliminary protective-device loading. They do not replace the wiring rules that govern an actual installation.

Use installed route length, conductor material, insulation class, ambient temperature, grouping, and termination conditions from the same design case. Identify one-way and round-trip lengths explicitly.

Wiring and Protection calculators by result

Wire ResistanceCalculate wire resistance from resistance per meter and conductor length.Wire Power LossCalculate wire loss from current and circuit resistance.Wire GaugeCalculate required conductor area from current and design current density.Continuous Load CapacityCalculate minimum circuit rating from continuous load and maximum loading.Breaker Load MarginCalculate unused breaker capacity from breaker rating and connected load.Electrical Fuse RatingCalculate minimum fuse current from operating current and design allowance.Short-Circuit CurrentCalculate prospective fault current from source voltage and total fault impedance.Current-Limiting ImpedanceCalculate required impedance from source voltage and maximum current.Fault Loop ImpedanceCalculate maximum loop impedance from nominal voltage and required trip current.Conductor Temperature DeratingCalculate derated ampacity from base ampacity and temperature factor.Bundled Cable DeratingCalculate bundled ampacity from single-cable ampacity and grouping factor.Parallel Conductor SharingCalculate current per conductor from total current and parallel conductors.Electrical Conduit FillCalculate conduit fill from cable area and conduit internal area.Cable Tray FillCalculate tray fill from cable occupied area and usable tray area.Junction Box FillCalculate remaining box volume from box volume and required conductor volume.Extension Cord Power LossCalculate cord loss from load current and round-trip cord resistance.Contact Resistance LossCalculate contact power loss from current and contact resistance.Insulation Leakage CurrentCalculate leakage current from test voltage and insulation resistance.Ground Electrode ResistanceCalculate estimated ground resistance from test voltage and measured test current.Grounding Voltage RiseCalculate ground potential rise from fault current and ground resistance.

Conductor sizing sequence

A practical sequence is to establish load current, continuous-duty allowance, conductor area, voltage drop or loss, and then fault and protective-device performance. Standard conductor sizes are selected after the arithmetic.

Parallel conductors require compatible material, length, termination, and impedance. Equal division is an assumption, not a guarantee when the physical paths differ.

Fault and protection checks

Prospective fault current and loop impedance must be compared with protective-device operating curves and interrupting ratings. A calculated fault value alone does not establish clearing time.

Fuse and breaker pages provide numerical targets. Equipment type, inrush, ambient correction, coordination, and applicable code rules remain part of final selection.

Raceways, boxes, and connections

Conduit, tray, and junction-box calculations need the actual cable or conductor dimensions used by the governing rule. Do not substitute conductor cross-sectional area for finished cable area.

Contact resistance and extension-cord loss can create localized heating. Inspect terminations and use measured resistance where a small connection loss matters.