The first layer of mechanical protection added over the coated fiber during cabling. A tight buffer is plastic extruded directly onto the coating to 900 µm, easy to handle and terminate directly. A loose buffer is a tube a few millimeters across holding typically 12 fibers that float freely in gel or dry water-blocking material, isolating them from cable stretch and temperature swings.
Cut the buffer tube with the tube cutter, not your knife, last guy scored straight through two fibers.
Do not mix it up with
- Jacket: The jacket is the outer sheath of the whole cable; the buffer protects the fibers inside it.
Related terms
Tight-buffered cable
Indoor fiber cable in which each fiber has its own 900 µm plastic buffer, ready to terminate directly.
Loose-tube cable
Outside plant cable whose fibers float inside gel-filled or dry tubes, protecting them from strain and temperature changes.
Two-fifty
Splicer slang for fiber that has only its 250 µm acrylate coating, with no tight buffer over it.
Jacket
The outer plastic sheath of a fiber cable, chosen for fire rating indoors and for UV and moisture resistance outdoors.