Congratulations on your new job!
I don't know about the above posters but I do work in a state psych hospital and I would not deem it as "dangerous" work. I am on acute unit so I deal with unpredictable patients at times but we are trained for those situations. Our top priority is safety so when problems flare up, we as a team act fast and follow hospital policy.
I encourage you to brush up on your psych meds, s/s of eps, neuromalignant syndrome and tardive dyskinesia.. Since you will be in long term care, many of the psych meds will be antipsychotics and probably some mood stabilizers. Here's a list of some common psych meds: clozaril, risperidone, risperidone consta, , haldol/haldol dec, geodon, zyprexa/zydis, seroquel, abilify, vpa/depakote, lamictal, topamax, cogentin. Most of these have extensive lab protocols, which you will become familiar with when you begin.
If it helps any, the long term rehab units in my hospital are usually quite calm. They have a routine and like to stick to it. The patients and staff become very close and sometimes are like second family. I hope some of this info has helped. Best wishes!