HOLT Electricians Practice Exam

Resistance heaters must be protected against personnel contact by being physically guarded or thermally insulated due to the high temperatures they can reach during operation. These heaters generate heat by passing electric current through a resistive element, leading to surface temperatures that can become dangerously hot. Without adequate guards or insulation, there is a significant risk of burns or other injuries from accidental contact.

The requirement for guarding or insulation is primarily a safety measure to prevent accidental contact with hot surfaces, which is crucial in both residential and industrial environments where these heaters are commonly used. Implementing such protective measures helps ensure the safety of personnel working or moving around the area where these devices are installed.

In contrast, other options such as convection heaters, fan heaters, and electronic heaters may have different operating principles or designs that result in lower surface temperatures or better inherent protection, making them less likely to require the same level of guarding or insulation.