By default the 3D view shows only objects belonging to levels from the ground to the selected one. To show levels at negative elevations you must select them, so levels above (and objects belonging to them) aren't displayed.

If you start drawing the wiring at level 1, and then select the basement, then the wiring won't be shown, because it belongs to an higher level.

The workaround is to change the 3D view settings so that it shows all levels: right click the 3D view and select "Show all levels", or press CTRL+ALT+A.