This achievement is story related and as such cannot be missed. It will unlock part way through chapter 6 the female ward.
Initially, make your way through the level finding a route up the stairs, into a room with a wheelchair on its side, up the stairs to the left and through a serving hatch until you reach the main chapter objective, to find three fuses to get the key from the laundry hatch. Behind you is a door and thankfully all three fuses are close by and moderately ok to find - they are all in separate rooms with enemies in! There is nowhere really to hide so I recommend you get familiar with the route back to the fuse room, enter one of the rooms, grab the fuse and run back, and jump over the counter if they follow.
You get a save when you put the last fuse in and push the button - I died just after as I had all 3 enemies on me and restarted by the fuse box with no enemies around!
Note, when you put the fuses in and push the button the key drops down the chute - you need to go back downstairs and follow the signs for laundry and the key is in the laundry hatch. Pick it up and achievement unlocked! Good luck!