Abstract: A through-floor electrical outlet fitting, for insertion into structural openings of minimum diameter. The device has means for interlocking with and conforming to such openings, and to those of a wide range of thicknesses, for locking the device in the opening. Raceway means in the device separate passage therethrough and transfer of electrical service cables for at least two different electrical functions or services, such as high and low voltage insulated cables. The device has intumescent means thereon, encircling the cable raceways to conform the length thereof to varying depths of structural openings, as fire rated insulating barriers, so disposed that there is no need for a multiplicity of devices or field adjustments for varying depths of structural openings. The device and above-floor service head portions are capable of accepting maximum size low voltage communication cables, through the use of a radiator separately mounted in the service head, to allow dissipation of heat to a non-sensitive area.