Is it true that a voltage or potential is present at a common wall outlet, but there is no current flow until a device is connected?

A voltage or potential indeed exists at a common wall outlet when it is supplied by an electrical system. Voltage can be thought of as the pressure that pushes electrical current through a circuit. Therefore, when an outlet is live, there is a potential difference (voltage) available at the terminals.

Current flow, however, only occurs when a complete circuit is established, which usually happens once a device is plugged into the outlet and turned on. The device creates a path for the current to flow, allowing it to operate. Without a device connected, there is no closed circuit, and thus no current flows, despite the presence of voltage.

This statement reflects an essential principle of electrical circuits: voltage can exist independently, but current only flows when the circuit is complete. Understanding this aspect is critical for safety practices in electrical work, as it highlights the importance of treating all outlets as potentially live and dangerous, even when no devices are plugged in.