what is the minumum distance away from a panel that you need to keep plumbing?
I have a sink that we want to install
on the wall perpendicular to the panel box,
about 4 feet away.
The only consideraton that should be taken is 110.26 of the NEC. This section gives all the dimensions for proper working and spaces around panels and other equipment. Since the electrical equipment is there already, there may be plumbing code that restricts installation distances of plumbing equipment that I have no knowldege of.