What happens when you connect two 120V circuits in parallel?

When two 120V circuits are connected in parallel, the voltage remains at 120V because in a parallel circuit, the voltage across each branch is the same as the source voltage. This is a fundamental characteristic of parallel circuits.

In addition to maintaining the voltage, connecting circuits in parallel increases the overall current capacity. Each circuit can contribute its own maximum current, allowing the combined circuit to carry more current than either circuit could handle on its own. For instance, if each 120V circuit is rated for 15 amps, together they can handle a total of 30 amps, while still providing 120V across the entire setup. This increased capacity improves the system's ability to power more devices or higher-load equipment without exceeding individual circuit limits.

This understanding is essential for safe and effective wiring in residential electrical systems, ensuring that circuits are not overloaded and function as intended.