View attachment 17944
These are the fuse boxes that have latched shut with rust. I ain't touching these. I'm gonna let a professional electrician tinker. I don't have a BCP in place for this.
This isn't a big deal. Pull the power switch. If IT is rusted open, THEN you need a pro to cut off the power into the building.
I imagine you only want to see what is in place.
Once power is off, use a block of wood as a fulcrum and just lever the box open with a pry bar.
In any event, you should ultimately replace this box with one with breaker switches versus fuses and probably add a lot more separate circuits than you now have. It will be a lot larger than the space for this one.
Although I know how to do all this work, I don't do it myself any more because I'm getting too old to crawl through attics and crawl spaces running conduit and pulling wire. My community does require a licensed electrician to do the final hookup to the power company feed.
If this were my building, I'd run all new wires and install new grounded outlets with strategic ground fault interrupters and bring to a new box before pulling this one. My circuit breaker box looks like this photo