Technical Standards and Safety Authority (TSSA) G3 Practice Exam

For current to flow through a wiring system, what must exist?

1. a difference in electrical pressure between two connected points

2. a difference in voltage between two connected points

3. a difference in power between two connected points

4. a difference in wire size between two connected points

The correct answer is: a difference in electrical pressure between two connected points

A difference in electrical pressure between two connected points is essential for current to flow. This is often referred to as voltage, which is a measure of the electrical potential difference between two points in a circuit. When there is a difference in this electrical pressure, it creates a driving force that pushes electrons through the conductor, resulting in an electric current. Voltage can be seen as the "push" that motivates the current to flow. Without this difference, there would be no incentive for the electrons to move, and thus, no current would flow through the wiring system. In contrast, a difference in power does not directly lead to current flow; power is a product of voltage and current, not a driving force in itself. Similarly, wire size does not affect the initiation of current flow; rather, it influences the current-carrying capacity and resistance in the circuit. Voltage is the fundamental requirement for establishing current flow, making it the correct choice in this context.