Why must ground & neutral be seperate in subpanel?

[The Streets]

Thanks for your help and advice. I've located a grounding bar kit from the panel manufacturer and will install it along with (4) wires from the main panel (white, greeen and two black) so that the neutral and ground are separate.

[David Combs]

Are there one or more books that actually coverf

*this* kind of stuff, ie that's being discussed in *this* thread?

Not some home-improvement book you might find at HD, but something that really, tutorially, gets down to the depth of *this* stuff, this "more complex" stuff than you usually see covered in the home-improvement-style electrical-books.

Something so that when you finish a subject, you really understand it, not so that you can merely "do" some home-job, but even would let you (correctly!, and usefully) contribute to eg this current thread.

Ideas?

Thanks!

David

PS: eons ago I took some EE courses in college, but of course that knowledge was pretty useless for this current subject.