What can be included in a panelboard?

A panelboard is a vital component of electrical distribution systems that serves as a centralized location for circuit breakers and other protective devices. The correct answer highlights that various automatic overcurrent devices can be included within a panelboard.

This versatility is crucial because panelboards are designed to house multiple types of devices that help manage the electrical load and protect circuits from overloads and fault conditions. Automatic overcurrent devices encompass not only circuit breakers but can also include fuses and other protective mechanisms that automatically interrupt the flow of electricity in the case of excessive current, thereby preventing potential hazards such as fires or equipment damage.

The other options don't capture the full scope of what can be housed in a panelboard. While circuit breakers are indeed a key component, they represent only one type of device. Similarly, restricting inclusion to only switches for lighting control or only voltage regulators fails to recognize the broader function of a panelboard, which is to accommodate multiple electrical devices for effective system management. Thus, various automatic overcurrent devices reflect the comprehensive functionality expected of a panelboard, making it the correct choice.