Electricity was generated at the Nine Mile Falls dam and transmitted to the Frequency Changing Station. Within, a portion of it was converted from Alternating Current (AC) to Direct Current (DC) and fed out to the Spokane streetcar system. The majority of the electricity was sent out as AC to more substations along the Spokane and Inland Empire Railroad, where most was converted to DC to power the electric railway. The remaining power was sent out as AC to power communities which the lines passed.
The station itself was built by the railroad in 1908 and used until 1939. It stood, apparently derelict, until 1978, at which time it was
converted into Apartments. On the exterior of the building one may still see a couple of the original pass-through insulators which carried electricity in or out of the station.
The main building was designed to house four motor generator sets, four 1250 kw transformers, three 375 kw transformers, and three 75 kw transformers. The east wing was added not long after the completion of the larger structure and contained a 550 volt (275 cell) chloride accumulator, or storage battery, with switchboard and exciter attachments. All of the equipment was removed apparently in 1939, when the property was sold by the owning railroad. Despite the absence of the electrical apparatus, the Frequency Changing Station remains a little altered representative of Spokane's railroading prominence.
The Frequency Changing Station was an important part of an early electrical power and transportation conglomerate. The name most often associated with this development is Jay P. Graves, the man who organized several small inter-urban lines into an extended system which connected Coeur d'Alene, Moscow and Colfax with Spokane;
a system known (under Graves) as the Spokane; and Inland Empire Railroad Company and finally (when held by the Great Northern Railroad) as the Spokane, Coeur d'Alene and Palouse Railway. Graves was also in the directorship of the Spokane Power Development Company which supplied power for this rail system and sold power and light commercially as well.
The Frequency Changing Station had a critical role in the railroad network. Receiving power from the hydroelectric plant at Nine Mile, the station delivered direct current to the streetcar system within the city of Spokane. At the same time, it also converted a portion of the power to alternating current for transmission to a series of substations placed about fifteen miles apart on the operating line. The substations converted power back to direct current to operate the facility outside Spokane and also sold 110 AC to the neighboring communities. The cost of electricity used by the railroad was computed at peak usage. To reduce the peaks, the storage battery was
installed shortly after the construction of the original plant. The storage battery was charged when demands on the system were low, and was discharged when demands were high, thus reducing the amount of peak power drawn from the Nine Mile generators. The batteries were attributed with a saving of 50 per cent in power costs.
From the NRHP Nomination Form