well can i safely assume the black is neutral and can be grounded
No the black is neither the grounded neutral nor the equipment grounding conductor.
200.7 Use of Insulation of a White or Gray Color or with Three Continuous White Stripes.
(A) General. The following shall be used only for the grounded circuit conductor, unless otherwise permitted in 200.7(B) and (C):
(1) A conductor with continuous white or gray covering
(2) A conductor with three continuous white stripes on other than green insulation
(3) A marking of white or gray color at the termination
250.119 Identification of Equipment Grounding Conductors.
Unless required elsewhere in this Code, equipment grounding conductors shall be permitted to be bare, covered, or insulated. Individually covered or insulated equipment grounding conductors shall have a continuous outer finish that is either green or green with one or more yellow stripes except as permitted in this section. Conductors with insulation or individual covering that is green, green with one or more yellow stripes, or otherwise identified as permitted by this section shall not be used for ungrounded or grounded circuit conductors.
It is very important that one understands the difference between the ungrounded, grounded neutral and the equipment grounding conductors. This is a process that will take more time than I am willing to give on a web site discussion forum.
If you don’t understand the difference between the two then it would be a very good idea to keep you fingers out of the circuit as one could be instant death and the other is what will clear a fault and save your life. One is a current carrying conductor and the other should never have current on it.
At any rate any wire other than green or white/gray is supposed to be hot and should never be connected where a green or white/gray wire is connected.