The outside plant is the telephone equipment that is not inside the central office and those tools necessary to support it. This includes building terminals, telephone poles, splices and lineman’s tools all of which are displayed in the museum.

Building Terminals

Building terminals are the subscriber or field connections to the telephone company’s circuits. The building terminals shown are from the period of about 1910 to the present. The wires from your house or business connect to these terminals.

Open Wire Lead

Open wire lead is composed of these components; telephone poles, crossarms, insulators and wire which are visible in the following photograph. A telephone circuit consists of 2 wires called a pair. In the early days materials used for insulating copper wires were inadequate so the two wires were physically separated to prevent short circuits. The open wire lead was installed in Seattle as early as 1883. Open wire lead was replaced with cables and now with fiber optic cable.


This exhibit shows different vintage splices. Splices connect wires of the same type to extend their length. Different types of conductors require different splices. Some of the splices shown are a fiber optic splice, early paper and paper pulp splice, and cable splices. The large splice on the bottom of the photograph is the largest copper wire splice which contains 4,200 pairs of wires. This splice might be found at the central office where the subscribers lines enter the building.