What causes a shorted control in an electrical system?

A shorted control in an electrical system occurs when contacts within a relay, switch, or similar device become welded closed. This welding can happen due to excessive current flowing through the contacts, which can generate enough heat to melt the metal, effectively creating a permanent short circuit. This condition leads to unintentional pathways for current flow, resulting in malfunctioning of the control circuit and potentially damaging connected components.

In contrast, a blown fuse typically interrupts the circuit to prevent damage, while loose connections can lead to intermittent issues rather than a definitive short. Overcurrent protection failure can result in excessive current flowing through the system, but it does not specifically imply that the contacts have welded closed. Therefore, contact welding stands out as the direct cause of a shorted control, making it the correct answer.