Earthing Question
The chassis and e.g. the transformer core should be connected to protective ground, but the secondary must be isolated for a laboratory power supply. A double isolation of the primary voltage is required for safety reasons. Also series connection of individual units must pay attention to isolation voltage ratings and safety rules. DC voltages above 60 V are considered dangerous and require protection against accidental contact.
P.S.: IEC 1010 respectively EN 61010 is the respective safety standard for laboratory instruments. A technical university should have it accesible in the library.