[vhcook]

I am having some trouble understanding your question.

Are you asking whether you can remove a segment from the Rockwell block that doesn't have any wires connected on either side? If so, yes, but you'll need to cut down the center jumper.

If you're asking if you have to use the Rockwell block at all for your negative leads, the answer is yes it's mandatory.

If I haven't answered the question you meant to ask, can you please rephrase or give us a picture to work with?