Does the NEC allow splices inside a load center (main circuit breaker panel)?
It is legal to splice inside the service panel. I regularly have to do this when replacing the existing panel, it is quite common. Another way is to add a gutter and use that if the location of the panel is moved, code requires the splices to be in an approved or listed box that is accessible the panel is appropriate but sometimes with older panels there is not enough room to do it in a neat and workmanship manner so I add a gutter.