What is the first step in grounding a circuit safely?

The first step in grounding a circuit safely is to disconnect the power source. This action is crucial because grounding a circuit while it is still energized poses significant hazards, including the risk of electric shock. When the power source is disconnected, it ensures that there is no current flowing through the circuit, making the grounding process much safer.

Additionally, wearing insulated gloves is important for protection during electrical work, although it is a precautionary measure that comes into play after ensuring the circuit is de-energized. Applying the earth clamp is part of the grounding process but should only be done after ensuring that the power source has been disconnected. Alerting other personnel is a good safety practice but does not directly address the immediate action required to safely ground a circuit. Therefore, disconnecting the power source is the foundational first step in maintaining safety during electrical grounding.