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Step-by-step explanations with worked examples, written to go with our calculators.
How to Size Wire for a 50 Amp Circuit (NEC)Which wire size works for a 50 A breaker? Compare copper and aluminum, THHN and NM-B, with derating and voltage-drop checks.Voltage Drop Explained: Formula, Limits and ExamplesLearn how to calculate voltage drop, why 3% and 5% matter, and how to fix excessive drop on single-phase and three-phase circuits.Conduit Fill Explained: NEC Rules and ExamplesHow NEC Chapter 9 conduit fill limits work: 53%, 31% and 40%, how to count conductors, and two worked examples.Motor Circuit Sizing Under NEC Article 430: A Worked ExampleStep-by-step motor branch-circuit sizing: table full-load current, 125% conductors, short-circuit protection and overload settings.EV Charger Circuit Sizing: Breaker, Wire and Panel CapacityHow to size a Level 2 EV charger circuit under the NEC: the 125% rule, breaker and wire sizes, and checking panel capacity.Power Factor Explained: kW, kVA, kVAR and Capacitor SizingWhat power factor means, how to convert kW, kVA and kVAR, and how to size correction capacitors with a worked example.15 Amp vs 20 Amp Circuits: Wire Size, Receptacles and When to Use EachCompare 15 A and 20 A branch circuits: 14 AWG vs 12 AWG wire, receptacle types, the 80% continuous rule and required 20 A circuits.How Many Outlets Can You Put on a Circuit? NEC Rules and Practical LimitsThe NEC sets no fixed outlet count in homes. See the 180 VA rule, a simple calculation for 15 A and 20 A circuits, and practical limits.100 Amp vs 200 Amp Service: How to Size a Home Electrical ServiceA worked NEC 220.82 load calculation showing when 100 A is enough, when you need 150 or 200 A, and how an EV charger changes the answer.Subpanel Wire Size: Feeder Conductors, Breakers and GroundsHow to size feeder wire for a 60 A, 100 A or 200 A subpanel, including the grounding conductor, neutral and voltage drop.LED Strip Wiring Guide: Wire Gauge, Power Supply and Voltage DropHow to wire 12 V and 24 V LED strips: choose wire gauge, size the power supply with headroom, and avoid dimming on long runs.How to Size a Generator for Your Home: Running vs Starting WattsA worked example for sizing a home standby or portable generator, including motor starting surge, safety margin and transfer switch rules.