Yes, there is some risk of later driving a screw or nail into the NM, but this is a common and accepted technique for running new cable in situations such as yours.

I would run at least type MC to avoid an inadvertent nail.

i will give it a try . thank you

Stretch and clamp it tight into corner.

Crown molding is nailed on the edges, and would be tough to put a finish nail in center, get it to hold and not split the molding.

"Crown molding is nailed on the edges, and would be tough to put a finish nail in center, get it to hold and not split the molding."

Very small can be nailed in the middle with little problem, a little larger and you do stay nearer the edges, larger often requires other tricks (like angled packing).

Very large built up crown has backers and a bunch of other 'tricks' to provide solid attachment (like ledgers with angled lookouts).

If the cable is placed before the molding it will have to be fastened in place.
If it is fished in after the molding is installed it does not require fastening.

thanks guys. my friend is a carpenter so i think i'll have him do the moulding