ARTICLE 770. OPTICAL FIBER CABLES AND RACEWAYSARTICLE 770. OPTICAL FIBER CABLES AND RACEWAYS770.1. Scope. This article is interesting in that it covers "wiring" that in some cases does not bring with it even a single conductive element, although the cabling will always be used in conjunction with electrical circuits. Figure 770-1 shows operation of a fiber-optic (FO) link in the transmission of a telephone signal.