These insulators were all used for house and building "low voltage" (240 VAC, 5-10 Amps) power distribution.

The T5s (CD 648) and T5S-S (CD 650) "spooks" were used outside the building, and then the wiring was then brought inside through porcelain wall tubes, and then to the T6 (CD 1076) and T6-bis (the smaller) spools.

The dark green MIVAs are 1920s vintage, the clear glass MIVAs 1930s-1940s, and the porcelain may be older or newer than those dates.

Typical "old house" construction was with solid stone walls, not hollow walls with splaster boards and studs, so the wiring mst likely was surface-mounted o the interior walls. The various power receptacles and light fixtures were also surface mounted.

Here are a T5S and a porcelain "T6 bis" mounted together on an outside bracket: [id=157739203]

Judging from the two thin bare wires leading up, it appears that the current handling requirements were rather low. Any pigeons or other small birds which attempted to use the bracket as a perch were going to be in for a very rude surprise...