A liquid cooling system having cooling units individually assigned to electronic component groups housed in a rack or a switchgear cabinet, which are to be cooled, and having a monitoring and control arrangement for monitoring a cooling temperature. Effective cooling and temperature monitoring is obtained because the cooling units are liquid cooling units and are connected via branch points to a common central liquid line system integrated into the rack or the switchgear cabinet. The control and monitoring arrangement is for monitoring the cooling temperature in the central liquid line system and for emitting an error signal when a predetermined or a predeterminable threshold temperature in a liquid return branch is exceeded, or when a predetermined or predeterminable threshold temperature difference between a temperature in an inlet branch and a temperature in the return branch is exceeded, or when the liquid flow falls below a predetermined or predeterminable threshold value.