Metal shelving units, in particular, can be a safety hazard. Indeed, in the industrial sector, lack of bracing makes their use illegal. This, however, can be fixed by adding some way of restraining the unit. Attaching them securely to a wall would probably be the least expensive option. Since racks are mostly supplied without enough bracing anybody bumping into them heavily may cause it to fold over sideways and the result can be tragic.

Unstable shelving units that are not against a wall may very well topple over and cause a serious injury to anyone caught in their fall. It is recommended that a strip of wood is attached to their top and is connected to another shelving unit or secured to the nearest wall.

If metal racking is fixed separately from other units or the wall, it must be well braced to make a totally rigid unit. Any movement in the joints at all will eventually cause the bolts to loosen and come undone.

Wooden shelving units must always be attached to a wall or firmly braced if you intend to use them as a free-standing unit.