The Trumbull Electrical Manufacturing Company of Plainville, Connecticut was a major builder of switch gear and a division of General Electric since 1914. Their fuse panels could be found in every commercial building of note.
In the early 1950's the Trumbull stage department was combined with that of GE. Of the theatres mentioned in the 1927 bulletin (below), all have been demolished with the exception of the Oshkosh Theatre which is a hardware store.
This 1937 bulletin heralds the invention and first stage application of the autotransformer dimmer but the cover illustration shows the resistance dimmer switchboard installed at the Bushnell in Hartford. That board featured a five-scene switching preset which was located in a central panel, far from the dimmers.
1937 Bulletin courtesy Rick Zimmerman
1927 Bulletin courtesy Building Technology Heritage Library