What device does a split bus electrical panel use to isolate the 120V circuits?

In a split bus electrical panel, the use of a double pole breaker is integral to isolating the 120V circuits. This device is specifically designed to handle both phases of the electrical supply and can disconnect power to the circuit when necessary.

When a split bus panel is employed, it separates the circuits into two groups: one for essential circuits and another for less critical ones. The double pole breaker serves to effectively isolate the 120V circuits by simultaneously controlling both legs of the split-phase system. This ensures that both poles are disconnected at the same time, providing a safer means of shutting off power.

The single pole breaker, while capable of controlling a 120V circuit, only impacts one leg and is insufficient for full isolation in this specific setup. A fused disconnect switch, typically used in different types of installations, provides a means to disconnect power but is not part of the regular circuit control within a split bus configuration. Lastly, a ground fault interrupter (GFI) is designed for protecting against electrical shock in particular circuits but does not function to isolate circuit power in the manner described for a split bus panel.