I work primarily in maintenance, with some installation work thrown in for good measure. in my bag, and what i'd recommend, is;
pliers, sidecutters and long nose pliers, 2 pairs of multigrips, 2 8" shifters, 3meter tape measure, a terminal, medium and really big flatblade screwdriver, and terminal and medium phillips head, large hammer, flat bastard file. 1" paint brush, stanley knife, metric and imperial ball ended allen keys, tap wrench and a fluke T1000 voltage tester/multimeter.
I almost always have a pen, notebook and a smal torch in my pocket, as well as the terminal screwdriver.
also, i have a hacksaw, hammer, conduit cutters, crimpers back in my cupboard if i need it.
At work, I don't have to worry about power tools or ladders, as they are supplied by the company. Most of my hand tools are sidchrome, and i was happy enough with these to buy almost the equivalent for home.
I did have a 6" steel ruler which was invaluable for lifting my sandwhices out of the press.
your union may have a list of what tools are expected of each employee, though of course you may add to it.
