Improving the energy balance of vehicles is an effective way of lowering CO2 emissions. Among other things, this does entail mounting demands on the power wiring system. The intention is, for instance, to adapt the drive train to facilitate such functions as more efficient recuperation, e-boost and sailing with the aid of a 48V starter generator and a 48V battery. In addition, it is a matter of electrifying mechanical components with the aim of energy-efficient demand management to save fuel. The 48V power wiring system as an addition to the 12V system is a promising option where the task is to make the low-voltage wiring system of vehicles in the mass-market segment more powerful.Raising system voltage to 48V has the effect of fundamentally improving the efficiency of electricity generation and power distribution in the vehicle because of the reduced current and therefore the diminished ohmic losses. Yet the reduced current also has direct impact on the cable harnesses because it allows the required cable cross-sections to be correspondingly downsized - a positive effect as it means thinner cable bundles and less weight.The presented paper focuses on the most important requirements and the protection needs within a 48V automotive wiring system including all aspects regarding wire routing (topology) and safeguarding of safety-critical functions, failure scenarios and degree of protection, the risk of arcing as main difference to the 12V wiring system, as well as overcurrent protection devices in comparison to the conventional 12V system.