If a new electrical outlet or light fixture is installed, it will almost certainly need wiring from a power source. To guarantee your personal safety, electrical devices must be installed in accordance with local building codes. The steps to extend cable between levels in different parts of your home are described below. Drilling or cutting joists should be done with care to avoid compromising the building's structural integrity. If you can reach the floor's subfloor, clip the wires between the joists rather than above them.