Electrical Service Calculations: 1,000 Practice Questions with Answers & Explanations Based on the NEC 2026

By Lodestar Press

1,000 service-calculation practice questions, built on the 2026 National Electrical Code (NEC) - every one with the full calculation worked and the NEC 2026 article reference. Load calculations are where exams are won and lost; this is the repetition that makes them automatic.

WHAT IS INSIDE

Ten parts of 100 questions each. Parts 1-5 build the method by topic:

Part 1: Residential Service Calculations. Part 2: Commercial Service Calculations. Part 3: Industrial Service Calculations. Part 4: Special Topics - HVAC, Appliances, EVSE, Multifamily. Part 5: Advanced Calculations.

Parts 6-10 are five 100-question challenge sets that mix all topics at exam-level difficulty.

An essential-formulas quick reference sits at the front, along with a guide to the tables and articles you will open most: Table 310.16, Table 310.15(C)(1), Chapter 9 Tables 1, 4, and 5, and Article 120 - where load calculations live in the 2026 edition.

NO ANSWER-ONLY KEYS

Every answer shows its work: the values, the formula, the demand factor or table lookup, the arithmetic, and the NEC 2026 article or table behind it. Dwelling demand on Table 120.45, dryers on Table 120.54, ranges on Table 120.55, dwelling service conductors on Table 310.12 - the chain is printed, so you can follow it, check it in your code book, and repeat it on exam day.

All references use 2026 numbering. Load calculations moved from Article 220 to Article 120 in this edition, and this book uses the new numbering throughout - make sure your code book is the 2026 edition.

WHAT YOU WILL GAIN

Load calculations carry more exam weight than any other single skill, and they are the questions candidates run out of time on. One thousand worked repetitions change that:

Automatic method. Dwelling, commercial, industrial, and multifamily calculations stop being four different problems and become one method you can run on anything the exam puts in front of you.

Speed under the clock. You stop re-deriving the demand-factor chain on every question, because you have already run it hundreds of times.

Field payoff. The same Article 120 path sizes real services, feeders, and panels at work. This is exam prep you keep using after you pass.

WHO THIS BOOK IS FOR

Journeyman candidates whose mock-exam misses cluster in calculations. Master candidates, for whom load calculations carry the exam. Working electricians who size services, feeders, and panels in the field and want the Code path to be second nature.

ABOUT THE AUTHOR

I'm a licensed electrician in Minnesota and an Air Force veteran. I've worked residential, commercial, and industrial projects across Minnesota, with a large portion being healthcare facilities. Today I run an electrical apprenticeship in Minnesota. I have watched good electricians - people who can wire anything you put in front of them - freeze up on a service calculation because they didn't know which table to open first. This book is the fix: do the work, over and over, until the steps become automatic.

Written by a licensed electrician.

Also in this series: Journeyman Electrician Exam Prep (620 questions), Master Electrician Exam Prep (620 questions), and Motors & Controls Exam Prep (500 questions) - all built on the NEC 2026.

• Format: Paperback
• Language: English
• ISBN: B0HP76B69M
• ISBN13: 9798165023156
• Release Date: October 2026
• Publisher: Independently published
• Length: 234 Pages
• Weight: 1.23 lbs.
• Dimensions: 11.0" x 0.5" x 8.5"