Thanks for the information. I'll ground the power tap for the N2K to the battery negative.
I also noticed while taking the old wiring out, there were some shielded cables, and some unshielded cables, usually for power supplies. Those were never grounded and I wondered what the point was of using shielded cables without grounding them.
The new wire I bought for power cabling is shielded, should it be grounded as well?