A method for heating a fluid (F) using a device for heating a fluid, having: - at least one electrically conductive pipeline for receiving the fluid (F), and - at least one voltage source connected to the at least one pipeline , wherein the at least one voltage source is designed to generate, in the at least one pipeline , an electrical current which heats the at least one pipeline to heat the fluid (F), - wherein the at least one voltage source has at least M outer conductors (L1, ..., LM), wherein M is a natural number greater than or equal to two, and wherein the at least one voltage source is designed to provide an alternating voltage on the outer conductors (L1, ..., LM), wherein those alternating voltages are phase-shifted in relation to one another by 2π/M, and wherein the outer conductors (L1, ..., LM) are electrically conductively connected to the at least one pipeline such that a star circuit is formed in which each outer conductor (L1, ..., LM) is electrically conductively connected to the star point (S) of the star circuit via at least a portion of the at least one pipeline , and - wherein the fluid flows through the at least one or more pipelines of the device and is heated therein in that the at least one pipeline or the plurality of pipelines is heated by a multi-phase alternating current flowing in the at least one pipeline or in the plurality of pipelines, so that Joule heat is generated in the at least one pipeline or in the plurality of pipelines, which Joule heat is transmitted to the fluid so that it is heated when flowing through the at least one pipeline or the plurality of pipelines, characterized in that - a preheated hydrocarbon vapor mixture as a fluid is heated in order to split the hydrocarbons, or - the at least one pipeline is designed as a reaction tube of a reformer. - at least one electrically conductive pipeline for receiving the fluid (F), and - at least one voltage source connected to the at least one pipeline , wherein the at least one voltage source is designed to generate, in the at least one pipeline , an electrical current which heats the at least one pipeline to heat the fluid (F), - wherein the at least one voltage source has at least M outer conductors (L1, ..., LM), wherein M is a natural number greater than or equal to two, and wherein the at least one voltage source is designed to provide an alternating voltage on the outer conductors (L1, ..., LM), wherein those alternating voltages are phase-shifted in relation to one another by 2π/M, and wherein the outer conductors (L1, ..., LM) are electrically conductively connected to the at least one pipeline such that a star circuit is formed in which each outer conductor (L1, ..., LM) is electrically conductively connected to the star point (S) of the star circuit via at least a portion of the at least one pipeline , and - wherein the fluid flows through the at least one or more pipelines of the device and is heated therein in that the at least one pipeline or the plurality of pipelines is heated by a multi-phase alternating current flowing in the at least one pipeline or in the plurality of pipelines, so that Joule heat is generated in the at least one pipeline or in the plurality of pipelines, which Joule heat is transmitted to the fluid so that it is heated when flowing through the at least one pipeline or the plurality of pipelines, - a preheated hydrocarbon vapor mixture as a fluid is heated in order to split the hydrocarbons, or - the at least one pipeline is designed as a reaction tube of a reformer. <EOS>