The wiring method in question is messenger-supported wiring. It's an exposed wiring support system. That is, there's a cable or other support that the conductors are affixed to [396.2]. You can look at any overhead "utility wires" between poles and see this wiring method. There are four ways this can be done, and factory-assembled ariel cable is one. See the others in 396.2.
There are three situations in which this wiring method may be used [396.10]. Basically, you can use it with the cable types listed in Table 396.10(A):
A. Under the conditions described in Article 396.10 or under the conditions described in the other Articles/Sections listed in Table 396.10(A).
B. In industrial establishments where conditions of supervision and maintenance ensure only qualified persons service the cables (and you can use it for MV cable in this situation, also).
C. In Hazardous locations where permitted in the relevant Chapter 5 Article.
You can't use it in hoistways. And, as usual, you can't use it where subject to physical damage [396.12].
- Article 396 does not specify the hardware you can use, but it does specify support requirements [396.30(A)]. You must use hardware suitable for this intended use [110.3]. If you're not sure what hardware you can use with the messenger cable you bought, ask your electrical distributor to find out for you.
- This wiring method doesn't use couplings and connectors. But make sure any conductor splices and taps are made and insulated by approved methods [396.56].