Method for operating an electrical system having a plurality of electrical loads (1, 2, 3...) which are connected to at least one power supply unit and are supplied with voltage (Ua) by said power supply system, - wherein the power supply unit either connects through a basic supply voltage (Ug) or in the case of a failure of the basic supply voltage (Ug) connects through a buffer voltage (Up) which is provided by an energy store unit, - wherein a switch-on delay time (tv) is predetermined or determined in order to carry out a regulated switch-on process of the electrical load (1, 2, 3,...), after the expiry of which at the output of the power supply unit either a basic supply voltage (Ug) or a buffer voltage (Up) is connected through characterised in that in the event of failure of the basic supply voltage (Ug) before expiry of the predetermined switch-on delay time (tv), an item of application software controls the switching on of the power supply unit, which is a combination of a delay time-dependent and energy storage charge level-dependent switch-on management and is designed so that the switch-on delay time (tv) begins to run again from the time instant of failure of the basic supply voltage (Ug) and is repeated up to a switch-on time, - wherein a first switch-on time (tel) is selected as soon as the basic supply voltage (Ug) or the buffer voltage (Up) is available, wherein for through-connection purposes of the buffer voltage (Up), the charge level was previously checked to determine whether it is sufficiently high or a threshold value of a charge level of the energy storage unit is exceeded, - wherein a second switch-on time is selected if the basic supply voltage (Ug) or the buffer voltage (Up) is to rest at the output of the power supply unit only after a multiple n of the switch-on delay time (tv) has elapsed, wherein n is a natural number and wherein for through-connection purposes of the buffer voltage (Up), the charge level was previously checked to determine whether it is sufficiently high or a threshold value of a charge level of the energy storage unit is exceeded. - wherein the power supply unit either connects through a basic supply voltage (Ug) or in the case of a failure of the basic supply voltage (Ug) connects through a buffer voltage (Up) which is provided by an energy store unit, - wherein a switch-on delay time (tv) is predetermined or determined in order to carry out a regulated switch-on process of the electrical load (1, 2, 3,...), after the expiry of which at the output of the power supply unit either a basic supply voltage (Ug) or a buffer voltage (Up) is connected through characterised in that in the event of failure of the basic supply voltage (Ug) before expiry of the predetermined switch-on delay time (tv), an item of application software controls the switching on of the power supply unit, which is a combination of a delay time-dependent and energy storage charge level-dependent switch-on management and is designed so that the switch-on delay time (tv) begins to run again from the time instant of failure of the basic supply voltage (Ug) and is repeated up to a switch-on time, - wherein a first switch-on time (tel) is selected as soon as the basic supply voltage (Ug) or the buffer voltage (Up) is available, wherein for through-connection purposes of the buffer voltage (Up), the charge level was previously checked to determine whether it is sufficiently high or a threshold value of a charge level of the energy storage unit is exceeded, - wherein a second switch-on time is selected if the basic supply voltage (Ug) or the buffer voltage (Up) is to rest at the output of the power supply unit only after a multiple n of the switch-on delay time (tv) has elapsed, wherein n is a natural number and wherein for through-connection purposes of the buffer voltage (Up), the charge level was previously checked to determine whether it is sufficiently high or a threshold value of a charge level of the energy storage unit is exceeded.