Question regarding word change between 2004 & 2009 NFPA 70E definitions:

In the 2004 edition, the definition for "Arc Flash Boundary Protection" states it is "An approach limit at a distance from exposed live parts........." and in 2009 it states "An approach limit at a distance from from a prospective arc source......"

In our facility, we have both 480 & 4160 VAC equipment residing in MCC rooms. It has been assumed that with the wording change, we can no longer have personnel enter these rooms unless they are wearing the appropriate level of PEE regardless if the MCC bucket doors are closed or not - the argument being that motor starters can pickup and drop out at any time and if they fail, an arc potential may exist, thus potentially exposing one who may be walking past such a unit when this occurs. One cannot rely on the doors to protect personnel. I have not found any documentation that addresses this situation specifically- the NFPA 70E seems to contradict this as they do show in the tables different values for doors open/closed. Are there any references that speak to this? Thanks.