## 4 Discussion  
The development of electromobility also poses a challenge for home electrical installations, especially from the point of view of the convenience of treating an electric car like a smartphone in the context of battery charging. However, due to the significant power of the load, it is necessary to analyze the condition of the installation and make users aware of how this process works. One of the potential problems causing the incorrect operation of loads or a threat to users is power supply asymmetry. The reason for this condition may be a significant load on one phase, which results in an increase in the current in the neutral wire, as well as asymmetry in the power supply of other three-phase receivers. A partial solution to this problem may be to oversize the cross-section of the cables and place the charging point close to the connection. Power cables supplying single-family buildings are usually significantly oversized. The analysis of current distortions, despite their seemingly small values up to several mA, proves the need to take these distortions into account in the design and operation of  
Figure 14: THD and individual harmonic content for different electric vehicles: (a) for the Alfa Romeo Tonale PHEV; (b) for BMW C Evolution; (c) for the E-Scooter ESA 800 (kick cocoter). home electrical installations in the context of their safe use and, in particular, the selection of anti-shock protection capable of disconnecting the circuit when necessary at currents other than sinusoidal without causing unnecessary disconnections. The distribution of voltage harmonics, i.e., the influence of the non-linearity of the load (converter in the battery charging system), indicates that the fifth harmonic has highest value, and the THD does not exceed 3%. It seems that these values should not cause any concern; however, due to the numerous presences of non-linear receivers in households, attention should be paid to protection. They should operate equally effectively with sinusoidal and distorted currents and voltages. Comparing the harmonic content for on-board and off-board chargers [36], it can be seen that in both cases, the harmonics of the following order have a significant share: 5, 7, 11, 13, 17, 19, 23, and 25. For on-board chargers, the above-mentioned significant harmonics content of the orders 3, 9, and 15 are also observed. This difference is related to the fact that in the case of off-board chargers, the charger's influence on the network is measured before the transformer, whose winding on the network side is connected in a delta, and on the charger side in a Wye [53], so the zero sequence symmetrical components are not transferred. Our research concerns measurements on the low voltage side in the TN system, i.e., on the side of the transformer connected in a Wye, which result in the occurrence of zero sequence components and may affect the operation of other devices. Based on the conducted research, the following conclusions, guidelines for both the users and designers of chargers installed in EVs, can be formulated:  
* All tested on-board battery chargers for EVs meet the requirements for the quality of electricity. * Charging the battery over 80% of its capacity is characterized by the possibility of dynamic changes in current consumption from the network, which, especially in the case of single-phase chargers, can lead to voltage asymmetry in the installation. * The occurring harmonics may result, depending on the power supply system, in the occurrence of zero, positive, or negative sequence components, which may affect the operation of other devices in the installation, i.e., by making their efficiency lower or increasing windings and insulation temperature; efforts should be made to reduce the share of higher harmonics. * Users must compare the power of the charger, especially line current, with the maximum line current and overcurrent protection of their installation.