| OFC/OFN |
Designation of Fiber Optic cable which meets Steiner Tunnel test |
| OFCR/OFNR |
Designation of Riser Fiber Optic cable which meets Riser flame test |
| Ohm |
Unit of resistance such that a constant current of one ampere produces a force of one volt |
| Optical Fiber Cable |
UL (Underwriter's Laboratories) Standard 1651; National Electrical Code (NEC) Article 770 of NFPA 70 |
| OSHA |
Abbreviation for Occupation Safety and Health Act (specifically the Williams-Steiger law passed in 1970, covering all factors relating to safety in places of employment) |
| Outgassing |
The percentage of gas released during combustion of a material |
| Overall Diameter |
Finished diameter over wire or cable |
| Overcoat |
Individual strands of tin copper wire stranded together and then covered with a tin coating |
| Overcoated Copper |
Stranded conductor with overall tin coating, typically used in AWG sized 28 through 18 AWG |
| Overlap |
The amount the trailing edge laps over the leading edge of a tape wrap |
| Oxygen Index |
Percentage of oxygen necessary to support combustion of a specified material |
| Ozone |
A highly active form of oxygen produced by the passage of electric discharges or sparks through air or oxygen |
