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Exam calculations, one topic at a time

Every article has a worked example with real numbers and the NEC article or table where each value comes from.

VOLTAGE DROP /

How to Calculate Voltage Drop for the Electrician Exam

Voltage drop for the journeyman exam: single-phase and three-phase formulas, where K and CM come from, and four worked problems with every step.

 CONDUIT FILL /

Conduit Fill Calculation, Step by Step

How to calculate conduit fill with NEC Chapter 9 Tables 1, 4 and 5: the 53/31/40 rule, the 0.8 rounding rule, and three worked EMT examples.

 BOX FILL /

Box Fill Calculation Examples (NEC 314.16)

Box fill counting rules from NEC 314.16 in plain terms, with worked examples for receptacle boxes, switch boxes and mixed conductor sizes.

 LOAD CALCULATIONS /

Residential Load Calculation: The Standard Method

A full dwelling load calculation using the NEC standard method: lighting, small appliance, demand factors, range, dryer, appliances, heat or AC, service size.

 OHM'S LAW /

Ohm's Law and Power Formulas for Electricians

Ohm's law and power formulas with worked problems: heater current, a 240 V element on 208 V, parallel resistance, power factor and three-phase power.

 AMPACITY /

Ampacity and Derating: Temperature and Bundling

How to derate conductor ampacity for ambient temperature and more than three current-carrying conductors, then check terminals. Three worked examples.

 MOTORS /

Motor Circuit Calculations: FLC Tables, Overloads and Branch Circuits

Motor circuit basics for the exam: table FLC vs nameplate, 125% conductors, overload sizing, Table 430.52 breakers and fuses, and a multi-motor feeder.

 TRANSFORMERS /

Transformer Sizing and kVA Calculations

Transformer kVA and current formulas for single-phase and three-phase, sizing a transformer for a load, and overcurrent protection with Table 450.3(B).

 THE EXAM /

How the Journeyman Exam Is Scored and Timed

What to look up for your state's journeyman exam: items, time, passing score, code edition and references, with Texas and Wisconsin examples from official pages.

 MISTAKES /

Common Calculation Mistakes on the Journeyman Exam

Ten setup mistakes that cost points on journeyman exam calculations, each with the wrong answer and the right one: voltage drop, motors, fill, derating, load calcs.