Leaving extra wire in the electrical panel for future use is not a bad idea. This deliberate excess, often called “slack” or “free conductor,” is a fundamental requirement in residential and. What are some rules of thumb for leaving extra wire within an electrical panel (if any) and routing the extra wire (e. create a single loop from the extra wire) to maintain balance between considering potential future wiring needs and also keeping the panel from turning into a complete rats'. Before installation, it's important to know what makes up a distribution box. When choosing one, check the IP or NEMA rating. Is there a middle ground for all of this? Yes, you can avoid the above situations by acting according to the NEC code.