This toggles on and off the wires connecting modules to the power supplies.

On more complex layouts, the power supply wires can be distracting, and turning them off might make it easier to see the layout.

Note that there are two ways to draw the power supply wires:

1. As curved wires from the end of the runs to the loaded power supply.
2. As straight lines that come down vertically from the runs then connect horizontally to the loaded power supply.

You can change the way the wires draw in the with the Options dialog box from the Tools Menu, LED tab: "Straight Power Supply Wires"

Remember that having the wires turned off in the layout is not the same thing as having them turned off for exporting. If you do not want to export the power suppply wires, you need to turn off that layer in the Export dialog box.

As a general rule when exporting, if it is very obvious which power supplies are driving which runs or letters, then it is probably Ok to turn off the wires. Otherwise, you should show the wires so there is no confusion.

Please also see Power Supply Colors as a way to more clearly see the power supply loading.