What is defined as a ground fault?

A ground fault is specifically defined as an unintended electrical connection between a live, ungrounded conductor and a grounded surface, which can include any conductive material that is part of the electrical system, such as a metal conduit. When an ungrounded conductor comes into contact with any grounded surface, it results in a fault condition that can lead to a short circuit, equipment damage, or even electrical shock.

In the context of the options provided, having an ungrounded conductor touching a metal conduit fits the definition of a ground fault, as the metal conduit typically serves as a grounding path. This scenario creates a potential fault condition that is dangerous and needs to be addressed.

The other options describe different scenarios that do not fall under the definition of a ground fault. For instance, two ungrounded conductors touching may lead to a short circuit, but does not involve a ground connection. Similarly, an ungrounded conductor touching a grounded conductor is part of the fault definition, but because option C includes the interaction with a metal conduit, it is more in line with the specific definition of a ground fault. Thus, option C stands out as the correct answer.