I have a light switch that is installed in a electrical box together with 2 other switches. I'm surprised that the switch has 2 hot wires. One wire is coming from the switch next to it, the other wire is the actual wire coming from the wall. All white wires of the three switches are joined inside the box.
Is there a reason why the electrian would install two hot wires for the switch?
Wiring – Light Switch two hot wires (one from wire another one from anothr switch)
switchwiring
Related Solutions
Yes, this is normal. There are two ways to wire a two-way switch with 2-core cable like you have:
one where the switch is between the supply and the light fixture(s). This is how your switches are wired.
As you can see from the diagram, the white wire is used -- it completes the circuit back to the electrical supply's neutral line.
one where the light fixture is between the supply and the switch. I think this is what you mean by a "standard black-white setup".
Note that the white wire in this case must be marked to indicate that it is carrying the electrical live; I use a small piece of black electrical tape wrapped around the insulation. It's common (in my experience with amateur wiring at least) for this step to be omitted.
(Images found here)
If you change the switches, you should follow the original wiring.
Since the 4 white wires are already connected, they need to stay connected. It would be correct to wire all 6 whites together. Note that for 6x #14 wires you need to use a new red wire nut.
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Best Answer
The wire from the other switch is almost certainly the line hot. If so, it will be always hot no matter what position either of the switches is in. This is electrically the same as having a separate wire going to each switch from a common line hot. I have a set of three switches in a 3-gang box wired that way.
The other wire also black should be the switched hot going to a light or a switched receptacle. It would be hot when the switch is on and not hot when the switch is off.