On that one, your ground can connect to the casing via one of the mounting bolts used to attach it to the metal box/sign frame. Yes, it is best to ground them, in part because the secondary on most of them is midpoint grounded (the reason that many transformers, even bombarders, use a midpoint ground is that it simplifies the mechanics of construction: The innermost wrap of winding is connected to the core and it is therefore at ground potential...the outermost wrap of coil winding is therefore only one half of the total output voltage...the two secondary coils work in series to give the total nameplate rated output but by splitting it all up this way, the porcelain bushings and other insulation involved only has to be rated to one half of that total with respect to ground. Keeping the transformer grounded avoids any stray buildup of voltage that may stress any of the insulation in its search for a return path, especially if a connection or tube is broken.
Since these do not fully self adjust like an electronic transformer does, it is important to properly load them. Consult a standard footage chart for starters. (since these are all going to output the same line frequency regardless of make, a generic footage chart works and you do not have to use a manufacturer specific one like you do with the electronic ones) If you want to go beyond the footage chart, you can more precisely load them with the use of a milliamp meter and a variac to determine the proper sized one to have for your load. If that is something you want to do, let me know and I can give you a detailed procedure for it.
One benefit of a traditional transformer is that unlike an electronic one, the output frequency is only 60Hz (or 50 if you are in a country that uses 50Hz power) and so the tendency to generate ozone is reduced, as is the tendency to interact with other transformers and cause nuissance tripping of protective circuits....the lower output frequency doesn't try to travel like the electronic ones do (because they are actually up into the RF spectrum) and so unless you have a true wiring fault, the ozone and interferance is less likely. The disadvantage of an older type transformer is the weight and the lack of those protective circuits (unless it is a new enough example to have them added in, which some do)
If you haven't used traditional transformers before, one thing you will notice right away is that they light up tubing a little differently....you can see it visually. Most people don't care, but I personally prefer the look of tubing lit with a traditionaly magnetic transformer and also find the faint 60Hz hum is comforting in a way.
