Running Board Requirements

It is not specified but usually they use 1x3 or 1x4s

There is no requirement that you even USE "running boards". I assume you are running cable and not pipe? The only thing the NEC requires is that the cable be "adequately supported", using staples or clips "listed" for the application. As a rule, support romex every 4 feet, and stretch it tight so that there are no sags or loops.

Hope this helps!

Glenn Grundberg

Article 334.15(C) specifically requires running boards when installing NM cable smaller than #6 across joists in an unfinished basement. Whether this applies to crawl spaces as well, the Code doesn't appear to specify, but I think I'd want to check that out with the local electrical inspector first.

My local area uses the 2002 version of the NEC, which seems to specify that for all 'exposed work'. This would seem to include crawl spaces, although there is some room for interpretation there. It seems that the only place I could get away with NOT using a running board to cross joists would be if there were already a ceiling in place and no way to access the wire for replacement. I'll just play it safe and pick up some 1x4 planks at home depot.