I am switching my kitchen receptacle to a GFI, it has 3 wires. I'm pretty sure I have to break the bar between the two hot screws, thus making the top and bottom on a separate circuit. What is the reason for this way of wiring? The outlet is not feeding anything else, it's on its own circuit with a double pole 15amp breaker. Seems a little usless to me. The house is 78.

I am switching my kitchen receptacle to a GFI; it has 3 wires. I'm pretty sure I have to break the bar between the two hot screws, thus making the top and bottom on a separate circuit. What is the reason for this way of wiring? The outlet is not feeding anything else, it's on its own circuit with a double pole 15amp breaker. Seems a little useless to me. The house was built in 1978.