OFNP stands for Optical Fiber Non-conductive Plenum. Plenum(OFNP) fiber cable is a cable containing only glass fiber with no copper conductive elements. It is a highest level which complies with the UL(Underwriters Laboratories) fire safety test. This kind of fiber cables contains very few fire barriers by being coated in flame-retardant, low smoke materials. Compared to the plastic cables, they will not burn or give off toxic fumes and black smoke. Nowadays, the fire department of many countries, especially the developed countries require their people to use the OFNP fiber cables in the plenum space.