Which term refers to any equipment connected to a source of voltage?

The term that refers to any equipment connected to a source of voltage is "Electrical equipment." This term encompasses a broad range of devices that operate using electrical power, including appliances, machines, and other systems that utilize electricity to function. The definition of electrical equipment under the NEC captures all kinds of apparatus that need a connection to a voltage source for operation.

In contrast, the other terms describe more specific categories or functions within the electrical field. For example, "current device" is not a standard term utilized in the NEC to define equipment connected to voltage sources, focusing more on devices that manage or measure electrical current rather than just being connected to voltage. "Grounded equipment" specifically refers to equipment that has a reliable path to ground, which is an important safety feature but does not broadly encompass all equipment connected to voltage sources. Lastly, "wiring device" typically refers to units like switches and receptacles that allow for electrical connections but does not include all types of equipment connected to a voltage source. Thus, the broadness and definition of "Electrical equipment" makes it the appropriate choice.