I seriously doubt that the 'neutral bus' is fused -- it's a corner grounded delta -- hence the fusing to the 'neutral' it's a grounded 'hot.'
I absolutely HATE to sling around the term 'neutral' in such schemes. While a corner grounded delta certainly has been pulled over to ground potential, it absolutely has circulating current pumping in and out of it -- at a tempo far beyond the residual imbalances typical of a center tapped residential service.
[ Unlike a center tapped Service drop, one dares not ever break the bonding to the ground while power is applied. What's bad for a center tapped ground is horrific for a lifted corner on a delta. ]
[ EUSERC hates this old time scheme so much that you'd need a Presidential Executive Order to have a new one hooked up. Emergency responders will always mistake the grounded corner -- from the layout of the panel -- to be that of a single phase, center-tapped scheme. Not good. ]
Off hand, it smells like a distribution panel for site lighting.
Which is exactly the kind of system that would run on and on for years without an upgrade/ overhaul.
I'd expect that the service was some ancient 240 delta.
That far back 480 was just not done for such facilities.
I used to see corner delta on sewer lift pumps. As soon as I figured out what it was, I never saw anything unusual about it. It seems to have a certain elegance to it. A grounded conductor is a grounded conductor. It is simply an arbitrary decision at which point we ground the transformer secondary. I would be a lot more concerned with the center of a wye when you have reactive loads than a corner delta. It will only draw nominal circuit current. The main code/listing issue is that there is 240v to ground so the 2 pole breakers need to be "delta" rated.