Electrician's Licensing Practice Exam

NEC Article 426 recognizes which of the following types of heating systems?

1. Induction, resistive, and convection

2. Resistive, impedance, and skin effect

3. Electric, radiant, and gas

4. Heat pump, resistive, and solar

The correct answer is: Resistive, impedance, and skin effect

The correct choice identifies the types of heating systems addressed by NEC Article 426, which is focused on the heating of conductors. Within this context, "resistive" refers to heating systems that transfer electrical energy into heat through resistance, as seen in appliances like toasters and electric stoves. "Impedance" relates to the overall opposition (including resistance and reactance) that an electric circuit presents to alternating current, which in turn can lead to heating within conductors. "Skin effect" describes a phenomenon where alternating current tends to flow near the surface of conductors rather than uniformly throughout the entire cross-section, causing additional heat generation in specific applications. This context solidifies the rationale for selecting this option, as the article addresses the functional characteristics associated with electrical heating methods. The other choices, while containing components that relate to heating, do not accurately depict the categories outlined in NEC Article 426.