Nice pics of vintage Square D equipment! Things looked not so bad at the 2nd image, then turned to "suck value" when the 200 amp switch was opened - showing the multiple conductors landing on the load side, then taking off in all directions!

One thought is [Linked Image]

Regarding antiquity of this equipment, I can say the XO breakers / bus kits were very popular for post WW2 residential services, running into around the early 1960's (or so), being cast aside by the introduction of the QO breaker / bus kit.
Haven't seen XOs used on commercial locations, but have seen many of the A1A / A2 frame styles. These look like a stretched out and long QO frame body, with an oversized reset handle.

The 200 amp switch looks similar to ones I have seen in locations built around circa 1950s.

The fuse panel looks like it also incorporates type M "Multiframe" breakers. The 4 breaker package on one mounting means thingees... Another circa 1940's residential type device.

Have upgrades or serviced a bunch of XO panels, and a few services with type M stuff.

The service entrance image shows some interesting variations in choices and usage of lugs! Split bolts, compression connectors, those ones with the bolts, and possibly a wirenut?

I was thinking along the same lines as Bjarney - as to the service types per usage.
Most of the older commercial locations I have dealt with used 2 separate service sections.
One for "Lighting" - which is 120 / 240 VAC 1 phase 3 wire,
One for "Power" - which is 240 VAC 3 phase 3 wire.
Both fed from the same 4 wire delta transformer bank (open and closed deltas have been used). The "High-Leg" is brought to the 3 phase section only, and it's normally around 50% smaller than the other two conductors.
The 1 phase service section has the GES connection (to the grounded noodle animal), and the 3 phase section gets bonded to the noodle in the 1 phase gear section.
Each section has a KWH meter.

Scott s.e.t.

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!