Abstract: Splicing optical fibers from cables running along an infrastructure involves passing the cables into a housing (80) having space to contain a fiber splice (100) and contain an additional length of slack fiber extending around a bend of at least 180 degrees, or a number of coils, in a substantially annular plane. After splicing, the fiber splice and slack fiber are placed in the housing, which is sealed to resist pressures of at least 200 psi, and the assembly is fixed to the infrastructure. The space in the housing can enable the housing to be used for protecting U-bends or to provide some slack fiber within the housing. This can enable faster onsite splicing operations or allow for rework without needing to relocate and strip more cable, to save costs. The housing can be suitable for fitting in the annular space between production tube and casing for use in sensing down boreholes.