IEC Study Guide 2026
Everything you need to pass the IEC 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.
📋 IEC Exam Format at a Glance
📚 IEC Topics to Study (63)
✍️ Sample IEC Questions & Answers
1. How many 90-degree bends are permitted between pull points in a conduit run?
NEC 358.26, 344.26, and related articles limit total bends between pull points to 360 degrees (four 90-degree bends).
2. The current a motor draws at the instant of starting when full voltage is applied, before the rotor begins to turn, is known as what?
Locked-Rotor Current (LRC), also known as Locked-Rotor Amps (LRA), is the inrush current drawn by a motor at startup when the rotor is stationary ('locked'). This current is typically 6 to 8 times the motor's normal full-load current and is a critical value for sizing short-circuit protection and motor controllers.
3. Under NEC Article 210, which branch circuit type is required for bathroom receptacles in a dwelling unit?
NEC Section 210.11(C)(3) requires at least one 20-ampere branch circuit dedicated to bathroom receptacles in dwelling units.
4. The term 'effective ground-fault current path' as defined in the NEC is an intentionally constructed, permanent, low-impedance path that facilitates what?
An effective ground-fault current path is designed to carry enough fault current to quickly operate the overcurrent protective device and clear the fault.
5. When installing a panelboard in a residential garage, what NEC requirement applies?
NEC 110.26 requires a minimum of 36 inches of clear working space in front of electrical panels.
6. When installing a feeder to a detached garage with its own subpanel, which practice is critical for safety?
In a subpanel located in a separate building, the grounded (neutral) conductor and the equipment grounding conductor must be kept separate. A separate equipment grounding conductor must be run with the feeder conductors to provide the effective ground-fault current path back to the main service. Bonding the neutral and ground at the subpanel would create objectionable current on the grounding conductors. A grounding electrode system is also required at the detached structure.