Dark fibre meaning

Dark fibre describes pre‑installed optical fibre (for example, in ducts or on poles) that is not active (“unlit”) and has no electronics or optoelectronics operating at either end. In practice, it is a passive infrastructure asset that can be leased or granted under an indefeasible right of use (IRU) so the customer provides and operates the transmission equipment. The term is descriptive rather than a defined statutory term. It is widely used in telecoms regulation, property and commercial contracts across England & Wales, Scotland, Northern Ireland and Ireland, with broadly consistent usage. UK and Irish regulators (Ofcom and ComReg) refer to dark fibre in market reviews and access remedies, but there is no single legislative definition. Key legal features and issues include: identification of specific fibres/route and handover points; continuity and splicing rights; fibre characterisation (attenuation/quality); maintenance, repair and fault access; service levels limited to passive availability; relocation/diversion; wayleaves and other consents; interaction with duct and pole access; capacity (strands/pairs), exclusivity and security; assignment and indefeasibility; term and renewal; and pricing (including IRU capital payments versus recurring charges). Dark fibre is distinct from “lit” services where the provider supplies bandwidth using its own active equipment.