Now it is comparatively easy to record the load profile of a washing machine over a wash cycle and assign appropriate line losses to the cable that only supplies this one load. The resolution could be refined further by making several recordings in different wash programmes and keeping a log for a year of how many of which wash cycles are run. The annual line loss costs could then well rise to 72 cents or fall to 68 cents. This can therefore be left as it is.
For other circuits that supply consumers with different load profiles, i.e. part-simultaneously, part-alternately, which is the norm, things become difficult. What helps in such cases, at least a little, is the comparative consideration of the most and least favourable cases. The truth should most likely be near the middle – of the previously described geometric average.
Thus, with its average annual consumption of 3110 kWh, a house connection for a terraced house chosen by way of example (built 1983, Table 3) is loaded with barely 1.5% of its rated capability of 3*35 A. The least favourable case (with the greatest possible line losses) would now be to draw the annual electricity consumption of the given household in the shortest possible time via as few circuits as possible. In the present case, this would correspond to a load of three circuits – one per phase conductor – of 17.6 A each via a circuit breaker B 16 A, since up to 1.1*In it is guaranteed that “nothing happens”. For the second three circuits – one per phase – a further 17.4 A is left over in each case in order to fully utilise the three 35 A main fuses, and the remaining 6 available final circuits stay unloaded. This load distribution would yield the greatest possible power loss across the residential distribution, and the annual electricity consumption of the chosen household would then run through the meter within 129 h. The annual energy loss would be around 29.6 kWh per phase, 88.7 kWh in total (Table 3).