http://www.dupont.com/cablingsolutions/pdf/buildings_article.pdf
Read this, the issues are related to the Fire Load and when situations where unused wiring is left and not made safe can be something covered by the local jurisdiction.
What’s Wrong Here?
Dec 11, 2006 2:37 PM, By Joe Tedesco
Hint: Seems a little tight here, doesn’t it?
This installer needs to try this again to get it right. Someone installed a new A/C unit, but no one removed the old one? This abandoned A/C unit and other equipment located behind an athletic club near the waterfront has been this way for more than six months. Whose responsibility is it to get rid on the old unit? Or do you even have to remove it?
http://ecmweb.com/nec/bad_mechanic2web.jpg
I imagine there will be some that will say, “This is not a problem,” however, this is a serious issue and impinges on the safe working space in this area, which is already deficient (see 110.26).
http://ecmweb.com/nec/bad_mechanic1web.jpg
At least there are some jurisdictions, like the state of Washington, who say, “all abandoned wiring shall be removed.”