A:  “A common thread in the installation of electrical systems is that the work be done in a neat and workmanlike manner

[NEC 110.12] and that conductors are not exposed to physical damage [NEC 300.4]. Physical damage is not specifically defined in the NEC or in ANSI/NECA 1-2010; however, it is generally understood as being self-defined.

“In a large PV power plant, the perimeter fencing and security system that keeps unqualified people out of the facility is sufficient to prevent physical damage due to unqualified persons. … Given the large amount of exposed dc cable used in PV arrays, it is understandable that wiring methods are as simple and cost effective as possible to keep installation and maintenance costs to a minimum.”  – Bill Brooks, P.E., White Paper: Cable Management in Solar PV Arrays, Pages 2-3, Jan. 16, 2014