When installing electric cables, it's crucial to avoid common mistakes to ensure safety and efficiency. One common mistake is using the wrong type or size of electric cable for the intended application. It's essential to select cables with the appropriate voltage rating, insulation, and conductor size according to the specific requirements of the electrical system. Another mistake is inadequate planning and layout of the cable routes, which can lead to excessive bending, stretching, or tension on the cables, potentially causing damage or reducing their lifespan.