The International Electrotechnical Commission (IEC) has recently released the Technical Report IEC/TR 61000-3-13 for the assessment of voltage unbalance emission by installations connected to medium voltage (MV), high voltage (HV) and extra high voltage (EHV) power systems, which is expected to provide the basis for developing a compatible Australian Standard. The philosophy of the approach described in this report is similar to the IEC recommendations for harmonics and flicker allocation. In addition, this involves a unique aspect, the contribution to global voltage unbalance by system inherent asymmetries, noting the fact that the voltage unbalance at a busbar can arise due to both load and system (essentially lines) asymmetries. Although the concepts and the basic principles used in this approach are widely accepted, the Technical Report IEC/TR 61000-3-13 is seen to require further refinements and original developments in relation to some of the key aspects. This paper reports, in summary, the work that has been carried out addressing: (a) propagation of voltage unbalance from MV to low voltage (LV) levels; and (b) global emission in MV systems due to line asymmetries, with the view to make contributions for further improving the present technical report.