This class provides an in-depth review of transformers based on the 2026 National Electrical Code. It covers foundational definitions, system grounding configurations, and specific code requirements for installation and protection.
Instructor: Ryan Jackson
Ryan Jackson is a highly experienced National Electrical Code instructor, author, and consultant based in Salt Lake City, Utah.
Class Summary
The course explores the technical and regulatory aspects of transformers, primarily focusing on Article 450 and related grounding requirements in Article 250.
Key Topics Covered:
Fundamental Concepts: Definition of a transformer as equipment that uses electromagnetic induction to change voltage and current from input to output.
System Grounding: Detailed analysis of separately derived systems, solidly-grounded configurations and the differences between ungrounded and impedance-grounded systems.
Overcurrent Protection: Application of Table 450.5(B) for primary and secondary protection, including "Transformer Math" for calculating full-load current.
Installation Requirements: Standards for ventilation, accessibility, physical clearances from combustible materials, and required markings/disconnecting means.
Specialty Transformers: Requirements for autotransformers, including their physical connections and specific overcurrent protection rules.
The class emphasizes practical application, such as sizing grounding electrode conductors and understanding when a system bonding jumper is required at the source versus the first disconnect.