ICC Residential Electrical Inspectors Practice Exam

The disconnecting means for heating equipment must have an ampere rating of at least what percentage of the total load?

1. 100%

2. 125%

3. 150%

4. 200%

The correct answer is: 125%

The requirement that the disconnecting means for heating equipment must have an ampere rating of at least 125% of the total load is grounded in the need for ensuring safe operation under potentially high demand conditions. This percentage allows for a margin of safety, accommodating not only the normal operational load but also the inrush or startup currents that can occur when heating equipment is first activated. Heating equipment often experiences a significant surge in current when it starts, which could exceed its normal operating load. By specifying a disconnecting means rated at 125%, it ensures that the equipment will function reliably even under these conditions without tripping or failing. This adherence to a higher percentage thus contributes to the overall reliability and safety of the electrical system. In contrast, the other levels such as 100%, 150%, or 200% are not aligned with standard practices for heating loads as they either do not provide sufficient allowance for surges or exceed the necessary requirements, complicating the design without beneficial reasoning. Hence, the choice of 125% is both practical and rooted in safety considerations.