|  | 8.7 | Planning Structured Cabling: Cabling and Grounding
| 8.7.4 | Avoiding potentially dangerous circuits between buildings
TIA/EIA-568-A specifications for backbone cabling permit the use of fiber-optic cable, as well as UTP cable. Because glass is an insulator rather than a conductor, electricity does not travel over fiber-optic cables. Therefore, when multiple buildings are to be networked, it is highly desirable to use fiber-optic cable as the backbone.