OFC stands for optical fibre cable, a cable that transmits data as pulses of light through glass or plastic fibre strands rather than electrical signals through copper. It is the physical medium underlying most modern high-capacity data and telecommunication networks.
OFC cable construction starts with the optical fibre and adds mechanical and environmental protection around it.
The core is the central glass region through which light travels. Its optical characteristics determine whether the fibre operates as single-mode or multi-mode.
Cladding surrounds the core. Its optical properties keep light guided within the core during transmission.
A protective coating covers the fibre and helps protect the glass surface during manufacturing, handling, and installation.
The buffer adds further protection. Fibres may sit inside a loose tube or receive a tighter protective layer around each fibre, depending on cable design.
Strength members carry tensile loads during pulling and handling so that excessive mechanical stress does not reach the optical fibres.
The outer jacket is the cable’s external protective layer. Its design depends on the installation environment, including ducts, buried routes, aerial routes, and indoor networks.
Single mode fibre has a narrow core, typically around 9 microns, which allows only one light path through the fibre. This limits signal dispersion and supports transmission over long distances with minimal loss, making it the standard choice for telecom backbone and long-haul utility links.
Multi-mode fibre has a wider core, typically 50 or 62.5 microns, and allows multiple light paths to travel simultaneously. This causes greater signal dispersion over distance, so multi-mode is generally used for shorter runs such as within data centres or campus networks.
| Parameter | Single Mode | Multi Mode |
| Core diameter | Around 9 microns | 50 or 62.5 microns |
| Light paths | Single | Multiple |
| Typical distance | Long haul, backbone routes | Short to medium, in-building or campus |
| Signal dispersion | Low | Higher |
| Common use | Telecom backbone, utility links | Data centres, LANs |
Loose tube construction houses the fibre inside a gel-filled or gel-free tube that allows the fibre to float freely, isolating it from mechanical stress and temperature-driven expansion. This makes loose tube cable suited to outdoor and long-distance applications.
Tight buffered construction applies the buffer coating directly onto the fibre, producing a more compact and flexible cable. This construction is easier to terminate and is typically used indoors, in patch cords and shorter structured cabling runs.
Armoured OFC cable includes a corrugated steel or aluminium tape layer beneath the outer jacket, giving it resistance to crushing and rodent damage. Unarmoured cable omits this layer, reducing weight and cost of handling but offering less mechanical protection.
The installation method determines which construction is appropriate:
| Cable Construction | Typical Installation Method |
| Armoured, loose tube | Direct buried |
| Unarmoured, loose tube | Duct |
| Armoured or unarmoured, aerial-rated | Aerial, pole to pole |
Fibre count refers to the number of individual optical fibres bundled within a single cable, and is specified as a simple number, such as 12F, 24F, 48F, 96F or higher. Higher fibre counts are used where future capacity or multiple network paths are needed from a single cable run, such as backbone and utility applications, while lower counts suit last-mile or drop connections.
OFC cable supports a wide range of networks:
OPGW, or optical ground wire, integrates optical fibres inside a cable that also functions as the earth wire on a transmission tower, combining fibre communication with grounding and lightning protection. OFC cable, by contrast, is a standalone communication cable with no grounding or structural role on the tower. Utilities typically use OPGW along the transmission line itself and OFC cable within substations, control rooms and connecting network segments. For a detailed look at OPGW construction and specifications, see our OPGW guide.
OFC cable is designed around the specific demands of the network it serves, whether that is long-haul telecom, utility communication or in-building connectivity. Selecting the right fibre type, buffer construction and armouring depends on distance, environment and installation method. Advait Energy Transitions Limited supplies OFC cable for transmission and utility communication applications.
