The upper crossarm carried higher voltages (typically 1,100 or 2,200 volts) and they were "transformed" to 110-volt for local electric lighting service (as on the lower crossarm). In most instances electricity wires with pintype insulators before c.1905 were glass.

Two of the upper crossarm's wires likely carried these higher-voltage "primary" lines while the other two could have been for series street lighting service.

In the early days (before c.1900) electricity generation was usually nearby for residential customers and lines like this with the forementioned voltages for such service were typical.