Increasing the conductor cross sectional area (CSA) of a cable reduces its energy losses. The most economic CSA is that for which the cable investment cost is equal to the total lifetime cost of energy losses.
Cable sizing is subject to regulation through national building codes, but these only take safety and aspects of functionality into account, not energy efficiency. These mandatory cable sizing prescriptions have given rise to the general misconception that following them precisely is best practice. The notion that the regulations are only the bare minimum requirement is often disregarded. As a result, economic cable sizing is not usually even taken into consideration during installation design or energy management initiatives.
Economic cable sizing cannot be derived just from the physical design parameters, but depends on the load profile of the electrical circuit in which the cable is used. Consequently, it is not the cable and its current-carrying capacity that should be regulated, but the choice of the cable cross section in the context of the electrical circuit and its load profile – in other words the installed cable system.
This review paper first looks back at the preparatory study performed in 2013-2015 in the context of the Ecodesign Working Plan. It summarises the findings from this study and proposes five comments to take this opportunity forward:
- The suitability of regulating systems in the Ecodesign Directive
- The scenarios of the preparatory study
- Identification of a standardisation gap
- Lockin of inefficient installations
- Future evolution of the load