Safety is limited to flash (optic-) and temperature- (IR?) sensors overlooking the bath,
which will should down the power and discharge a (modest) foam extinguisher into the bath.

The manual is not overly specific (attached) as to the dielectric fluid to be used;
"kerosene" seemingly being quite acceptable.

The bath's depth can be set (manually) using a simple mechanical slide with a switch on a float;
apparently you can etch above- or below the dielectric fluid
(at the time, they were etching above, with the kerosene jets playing on the part being etched).

Am I alone in finding this setup/technique alarming?
This EDM has been operated thus for almost 20 years without incident...