Wiring – how to wire a polarized wire to a switch

This is a bit more annoying than it looks (spoiler: the obvious way to wire it may not pass muster with all inspectors)

The power feed to this all comes in at box 1 (vanity light) and feeds the /2 switch loop to box 3 as well as the /2 feed to box 2. Box 2 and Box 3 are connected by a /3 cable, apparently intended to be a switch loop.

With all this, you'd think you'd be able to:

1. Turn the power off, of course
2. Connect the white wire from the /2 in box 2 to the white wires from the light and fan there.
3. Connect all grounds together in box 2 and to a box ground pigtail (if it's a metal box)
4. Connect the black wire from the /2 cable in box 2 to the white wire in the /3 cable and mark that white wire as a hot (permanent marker as you have done should be fine -- it just needs to be a permanent/indelible marking, visible from all angles).
5. Connect the red wire from the /3 cable in box 2 to the blue wire from the overhead light.
6. Connect the black wire from the /3 cable in box 2 to the black wire from the bath fan.
7. Connect all the grounds in box 3 together.
8. Connect the white wire from the /3 cable in box 3 to the HOT terminal on the fan controller after marking it as a hot.
9. Connect the black wire from the /3 cable in box 3 to the 1-POLE terminal on the fan controller.
10. Connect the white wire from the /2 cable in box 3 to the switch HOT terminal, again after marking it hot.
11. Connect the black wire from the /2 cable in box 3 to the switch 1-POLE terminal.
12. Connect the red wire from the /3 cable in box 3 to the other switch 1-pole terminal -- the Adorne parts can terminate two wires on each terminal.
13. Button everything back up and turn the power on.

and have it work. In fact, it will work if you do this; however, there's a catch! This arrangement takes one switch loop feed (from the vanity light) and returns it back down two different cables (to the vanity light and to the overhead light), which can be seen as a Code violation (of the 300.3(B)/310.10(H)/300.20 complex) as it creates a large loop area that puts out stray magnetic fields in your bathroom (good for ruining the picture on that old TV you have mounted in the wall in there ;).

A more conservative approach would be to utilize a dual pole switch to break the two hot feeds simultaneously while sending the return paths back the way they came, as follows:

7. Connect all the grounds in box 3 together, and to grounding (green/bare) pigtails to any switches that need them.
8. Connect the white wire from the /3 cable in box 3 to two (preferably black) pigtails after marking it as a hot. One pigtail goes to the HOT terminal on the fan controller and the other goes to one side of the dual pole switch.
9. Connect the black wire from the /3 cable in box 3 to the 1-POLE terminal on the fan controller.
10. Connect the red wire from the /3 cable in box 3 to the other terminal on the same side of the dual pole switch as the pigtail.
11. Connect the black wire from the /2 cable in box 3 to the other side of the dual pole switch.
12. Connect the white wire from the /2 cable in box 3 to the other terminal on the other side of the dual pole switch.
13. Button everything back up and turn the power on.

This arrangement also works, and keeps the two light switch loops neatly separated. However, Legrand does not make a two pole Adorne switch, and I do not believe there are faceplates available for the combination of an Adorne device side by side with a standard switch in a two gang box. You'd have to get a standard-form-factor (i.e. not Adorne) fan controller to do this.

Your switch on the left has the HOT Wire coming in to it. The two blacks - one of those blacks is a jumper to the other switch.

The White wires are not neutrals otherwise when you flip the switch you would have a dead short between hot and neutral and your CB should trip!

The wiring violates code!

The box looks like a DIY'er installed it - and that would explain the wiring.

Normally - your hot run would come into the box (3-wires black, white and copper in a jacket : Romex wire) from the Circuit breaker panel or as part of a loop. You would then have 2 sets of Romex (jacketed wire - 3 wires in a jacket) going out from that box to each light.

Inside your box the whites would be tied together with a wire nut and the grounds would be tied together with a wire nut.

You would have the hots (black wires) Black from CB panel on bottom screw of switch - with the black jumper to the bottom screw of the other switch, and a black from your outside light 1 to the top screw of switch 1, and a black from your outside light 2 to the top screw of switch 2.

What this means is those outside lights are wired wrong as well - just looking at the wiring - as sharp minded Harper pointed out current is probably carried by the ground! - I would say he is right on point too - because a DIY'er went cheap with the wire runs - that is why those whites are being used as hots! Now I will bring up something else - the hot coming in to this box might be fed from another nearby circuit - near to the outside light or near to the switches there - either way probably SCREWY!

Now to add an additional outlet to that box as part of a combo - First FIX your wiring to be correct according to proper practices and CODE. Then you can put a combo switch/outlet in the place of one of those switches. You should be able to do this with 3 Romex cables - 1 From box to Light 1, 1 From box to Light 2, 1 From CB panel (or from a loop) to Box.