I am now in the process of replacing the fitted kitchen I installed 17 years ago. The base units I fitted back then had a six inch wide horizontal bar stretching along the back of each unit which enabled me to screw the units to the wall.
The new units don't have this bar. There are fasteners provided which enable me to secure a unit to its neighbouring unit but nothing to enable me to secure the whole lot to the wall. Is this normal these days?