Plastic covered wires that run along the top of your baseboards are dangerous, because they can easily be damaged. It is so easy to just add a wire like this that it is often done, with extension cords, or even regular wiring simply being nailed to the baseboards to keep them off the floor.
If this is low voltage wiring, it is not safe for the wires, but not dangerous for fire. But when this is 110 or even 220volt wiring, it must be protected.
You can get both plastic and metal raceways designed for surface wiring, even electrical boxes that sit safely on the surface of the baseboard.
When working with electrical wiring you need to figure out which fuse or circuit breaker protects which circuit. There are electronic gadgets to help with this.
For more information follow this link to identifying circuits. Click here for information on the LEGALITY OF DIY ELECTRICAL WORK.