I have a fused power inlet with a voltage selector (Schaffner FN1394-10-05-11). I want to connect it through a separate DPDT switch to a transformer with dual 115V primary windings, and make everything work on either 110-120V or 220-240V grids.
Here is the wiring diagram for the inlet and voltage selector:
Top position on the voltage selector is parallel wiring for the four outputs (for 110-120V), and bottom position is series wiring (for 220-240V). The four outputs on the inlet are numbered 2-4-3-1 from the top down in the diagram.
The DPDT switch is pretty simple, it just has two sets of terminals, each consisting of an open-closed-common triple. When the switch is open, both open terminals short to common, and when it's closed, both closed terminals short to common. (Two separate common terminals.)
The transformer is also simple: two 115V windings, four wires.
What is the correct way to wire the inlet to the switch to the transformer, assuming P is the mains hot wire?
PS: I know that the inlet has a built-in switch. I want a separate switch because it has a nice LED on-off display and will be on the front panel of the device, rather than its back.
PPS: When connecting mains wires to the primary windings, does polarity matter?
(I think that wires 1 and 4 should run to the two closed terminals on the switch, and the common terminals on the switch should run to matching wires on the transformer. Wires 2 and 3 should go directly to the transformer. That way, when the switch is open, the hot wires terminate at the switch, no matter what the voltage selector switch is set to.)