Electrical Engineering Reference & Sizing Articles
In-depth technical guides, formula derivations, code compliance explanations (NEC 2023 / IEC 60364 / IEEE), and step-by-step practical worked examples.
Home Generator Sizing: Running Watts, Starting Watts and the Transfer Switch
Size a home backup generator from running watts and starting watts, not from the headline wattage alone. A worked example with a fridge, well pump, furnace fan and lights shows why the largest motor decides the peak rating.
Detached Garage Feeder Sizing: Wire, Voltage Drop and the Separate Grounding Rules
Size a detached garage feeder the right way: ampacity first, voltage drop second, and the detached-building grounding and disconnect rules that a normal subpanel guide does not cover.
Well Pump Wire Sizing: Why a Long Run Needs a Bigger Wire Than Ampacity Alone
Size a well pump circuit from the motor current, then check voltage drop over the real run length. A 1.5 HP pump 200 ft away is the classic case where the wire passes ampacity but fails voltage drop.
Van and RV Solar + Battery Sizing: How Many Panels and How Much Battery for Your Daily Use
Size a van or RV solar and battery system from your real daily watt-hours: panels from peak sun hours and derating, battery from usable depth of discharge and inverter loss, and charge controller from array watts.
Subpanel Feeder Sizing: 60 A Subpanel 100 ft Away, Step by Step
Size a 60 A subpanel feeder the right way: check ampacity and voltage drop separately, watch the NM-B temperature trap, and pick breaker, wire and ground with a worked 100 ft example.
EV Charger Circuit Sizing: Breaker, Wire and Voltage Drop in 5 Steps
Size a Level 2 EV charger circuit the NEC way: apply the 125% continuous-load rule, pick the breaker, check wire ampacity and voltage drop, and avoid the common NM-B trap.
Grounding vs. Bonding: NEC Article 250 Principles & Conductor Sizing
Comprehensive engineering reference on the vital distinctions between grounding (connecting to earth) and bonding (joining metallic parts to create a low-impedance fault clearing path) under NEC Article 250.
Conduit Fill Percentage and Jam Ratio Calculation Guide
Learn how to calculate conduit fill capacity per NEC Chapter 9 (Tables 1, 4, and 5), avoid cable jamming on multi-conductor pulls, and size pull boxes.
Solar Battery Bank Sizing Guide: Depth of Discharge & Peukert Derating
Comprehensive engineering sizing guide for off-grid and backup solar battery banks, incorporating daily Watt-hour audits, Depth of Discharge limits, temperature derating, and Peukert factor effects.
Transformer Sizing and Full-Load Current Calculation Guide
Learn how to calculate primary and secondary full-load amps for single-phase and three-phase transformers, determine required kVA capacity, and size overcurrent protection per NEC Article 450.
How to Calculate Three-Phase Motor Full-Load Amps (FLA) & Sizing
Step-by-step engineering guide to calculating three-phase induction motor full-load current, starting inrush, branch conductor sizing (125%), and overcurrent protection per NEC Article 430.
Battery Engineering Fundamentals: Ah, Wh, C-Rate & Chemistry
Essential technical reference covering battery capacity metrics (Ah vs. Wh), Depth of Discharge (DoD), State of Charge (SoC), C-rates, cycle life, and Lead-Acid vs. Lithium comparison.
Power Factor in AC Circuits: Theory, Triangle & Correction
Complete guide to AC power factor, the power triangle (kW, kVA, kVAR), leading vs. lagging power factor, utility penalties, and power factor correction capacitors.
Understanding Voltage Drop: Formulas, Consequences & Mitigation
Learn what causes voltage drop in electrical wiring, how to calculate resistance losses over long distances, code recommendations, and how to prevent brownouts.
Electrical Wire Sizing: Engineering Principles & Code Considerations
In-depth guide to properly sizing electrical conductors based on thermal ampacity, voltage drop limits, ambient temperature correction, and conduit bundling factors.
Ohm's Law: Theory, Formula Wheel, and Practical Engineering
A comprehensive guide to understanding Georg Ohm's fundamental electrical law, the Ohm's law circle formula wheel, limitations, and practical circuit examples.
Master Electrical Formulas & Equations Cheat Sheet
Complete engineering reference cheat sheet covering DC circuits, AC single-phase & three-phase formulas, Ohm's law, power, impedance, reactance, and transformer ratios.
How to Size Electrical Wire Properly: NEC Ampacity & Voltage Drop
Complete practical guide to sizing copper and aluminum electrical wire using ampacity tables, temperature correction, conduit fill derating, and voltage drop formulas.
How to Size a Power Inverter for Off-Grid, RV & Backup Systems
Learn how to calculate continuous wattage, surge startup wattage, waveform selection (Pure Sine Wave vs. Modified), and DC cable sizing.
How to Size a Battery Bank for Solar, RV & Backup Power
Complete step-by-step sizing guide for calculating required battery capacity (Ah and Wh), Depth of Discharge, and temperature derating.
How to Calculate Voltage Drop: Step-by-Step Engineering Guide
Learn how to calculate cable voltage drop for long wire runs, apply NEC 3% and 5% rules, and select correct conductor sizes.
How to Calculate Electrical Power: Step-by-Step Guide
Master calculating Watts, Kilowatts, VA, and Horsepower for DC and AC circuits with clear worked formulas and practical examples.