CEI Study Guide 2026
Everything you need to pass the CEI exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 CEI Exam Format at a Glance
📚 CEI Topics to Study (69)
✍️ Sample CEI Questions & Answers
1. When should an electrical inspector call for a re-inspection after a failed inspection?
A re-inspection is appropriate only after the contractor has corrected all cited deficiencies and formally notified the inspection office that the work is ready.
2. What is the purpose of a combiner box in a large PV array installation?
A combiner box aggregates the output of multiple PV source circuits (strings) into a single PV output circuit, typically including fuses or breakers for each string.
3. What is the main goal of electrical safety regulations?
The main goal of electrical safety regulations is to protect individuals and property from the inherent hazards associated with electricity, such as electric shock, electrocution, fires, and explosions. These regulations establish minimum standards for the design, installation, maintenance, and operation of electrical systems. By enforcing these rules, they aim to minimize risks and prevent accidents, ensuring a safe environment for everyone.
4. Which conductor in a feeder must be identified by white or gray insulation, or three continuous white stripes for sizes 6 AWG and smaller per NEC 200.6?
NEC 200.6 requires grounded conductors (neutral) 6 AWG and smaller to be identified by continuous white or gray insulation, or three continuous white stripes.
5. NEC 705.12(B) sets a limit on the size of a back-fed breaker relative to the panel's busbar rating. What is the '120% rule'?
The 120% rule states that the sum of the main breaker ampere rating plus the back-fed breaker ampere rating must not exceed 120% of the panel's busbar ampere rating.
6. What is a Zone 0 hazardous location characterized by?
Zone 0 is the most hazardous zone where flammable concentrations exist continuously or for long periods during normal operation.
🎯 Free CEI Practice Tests
📖 CEI Guides & Articles
What Practice Test Geeks adds beyond an AI chat for CEI
An AI chatbot can quiz you, but it can't reproduce the exam conditions or keep your record. Here you get:
- A timed, full-length CEI mock exam — 100 questions in 120 minutes with a 75% pass mark, modeled on the official exam's question count and time limit, followed by a score report broken down by exam domain.
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- Progress saved on your device: completed tests, scores and missed questions stay in My Progress, so you can retake only what you got wrong.
- A printable CEI cheat sheet you can print or save as a PDF.
- CEI flashcards built from the same question bank.
- Free CEI practice tests with the correct answer shown after each question.