Every panel and many external components in an electrical control system must be grounded by connecting ground wire to the __________.

Grounding is a critical safety measure in electrical control systems, helping to prevent electric shock hazards and ensuring proper operation of the system. Connecting the ground wire to the main power ground conductor is essential because the main ground acts as a reference point for all grounding within the electrical system.

This conductor is typically connected directly to the earth, creating a low-resistance path that helps to dissipate any fault currents safely into the ground. By grounding panels and external components to this conductor, you ensure that all parts of the system are at the same electrical potential, which reduces the risk of electrical shock and equipment damage. Adequate grounding helps in suppressing electrical noise and improving the overall reliability of the control system.

In contrast, while other options may relate to components within an electrical system, they do not provide the same level of safety connection or assurance of effective grounding. For example, the neutral conductor is primarily used for returning current in a circuit and doesn't provide the same protective grounding function as the main power ground conductor. Similarly, the power supply or control circuit options are more focused on power distribution rather than safety and grounding. Thus, the main power ground conductor is the appropriate choice for grounding panels and external components in an electrical control system.