I have to say first that I found quite a similar question under https://www.physicsforums.com/threads/poynting-vector-dilemma.331375/ However those thread ended without real answer. There shall be the following simple setup: A battery, and quite at a distance a light bulb. They are connected by two parallel wires. The entire configuration shall be located in, say, vacuum, and shall be operated stationarily. This is what I assume to know: Apart from minor distortions due to losses in the wires the Poynting vector field looks quite simple: The energy flows in the vacuum, parallel to the wires. In the spacetime picture the energy flux lines are timelike (a typical value for the velocity is about 2/3 of the velocity of light). Such electromagnetic field is not a radiation field. The vector potential has one temporal component and one spatial component parallel to the wires. Both are independent of time. So there are no waves and no transversal degrees of freedom. Questions: What I said above, is it correct? Is it true that energy transfer nevertheless occurs in quanta? If so, what field is to be quantized, what is the energy and the current of these quanta?