Yes, there are high resolution pictures of the top and bottom sides of the UT125C PCB on HKJ's website.
Can you pop the fuse out and confirm which end the positive lead is connected to?
Edit: it appears from one of HKJ's other photos that it is connected to the top (near the PTCs) as one would hope.
Yes, the positive lead is connected to the side of the fuse that meets the PTCs. So I would guess if ever there is a transient that arcs across the gap, it should blow the fuse?
It will blow the fuse, but they are slow devices. If current trough the fuse creates plasma near input terminals, it can resume taking current there, directly, and keep sustaining there, taking fuse out of the circuit.
In permanent installations, the only way to stop it is to cut power closer to the source, via protective switch that is designed for such fault current disconnections, otherwise it can arc over too... Unstopped, arc can travel hundreds of meters down the cables... It is a scary thing.
In this case, input cables would fail, and if there is a bit of luck they are connected to two sides far enough, it might extinguish when cables gap gets to big..
But all that is just talk.
People working on these kinds places where there is so much energy, should have proper tools, protective equipment and training in proper procedures and safety.
These meters are not what should be used in that case. No current range should exist on meter. Only noncontact current measurement....