
Hole Size: At least 0.53" wide, at least 1.08" tall. The schematic that came with the switch is NOT wrong, it's just confusing. In the schematic, the terminals are listed as 1, 2, 3 and the switch is labeled A, B, C. As someone else checked, A=1, B=2, etc. The other confusing part of the switch is the mains connection (120V AC). black input wire) and the load terminal (the black 120VAC wire that goes to what you control with the switch) are silver colored, while the neutral terminal (the white 120VAC wire) is brass colored. This is the OPPOSITE of the color coding of the connectors on a standard outlet, so don't be fooled by inverted colors.