Charging safety and the test certificate

• An extension cord, especially one wound on a reel, heats itself up.
• On a long cable the voltage drops, so the charger runs at its limit.
• A cable through the corridor gets in the way, lies across the doorway and draws electricity from a meter nobody knows the owner of.

• The cross-section for 11 kW is typically 5×2,5 to 5×6 mm², and for a single-phase socket 3×2,5 to 3×4 mm². The cross-section increases with length, because voltage drop is taken into account, not just current.
• The breaker is 16 A for 11 kW three-phase or 3,7 kW single-phase, and 32 A for 22 kW or 7,4 kW.
• Surge protection is recommended, especially with older wiring. It protects both the charger and the car.

Ask the contractor for:

• their name and licence;
• whether the quote specifies a dedicated circuit, RCD protection (in the board or in the charger), and the cable cross-section and length;
• what is at the end of the circuit: an industrial socket or a wallbox, not a Schuko;
• whether the test certificate is included in the price and whether you get it on the day of installation;
• whether there is a warranty on the work, not just on the device, and who comes out when it does not work, and within how many days;
• where the MID meter is, if the electricity is not yours: who pays for electricity.

Testing follows SRPS HD 60364-6. For a charger circuit, the following are measured and checked:

• continuity of the protective conductor, from the board to the socket;
• insulation resistance of the conductors;
• fault loop impedance, so that the breaker disconnects quickly enough in the event of a fault;
• RCD: tripping current and tripping time;
• earth resistance, polarity and a functional test of the charger.

The measurements take 30–60 minutes and are done right after installation, and you get the document the same day. It states who tested what, where, when and with which instruments, with the results, a conclusion and a signature. Without that, it is not a test certificate but just a piece of paper.

The word “atest” usually means one of two documents.

• The test report is issued by the installer after the work. The Rulebook on technical standards for low-voltage electrical installations requires testing before the installation is handed over to the user. For a home charger, this is the document you need.
• A licensed inspection report (stručni nalaz) is issued by a company licensed by the ministry responsible for labour. It is mandatory for electrical installations in workplaces, at prescribed intervals. It is not prescribed for a charger in a private garage.

In winter the charger works the most and the contacts are under the greatest thermal stress. That is why once a year, before the season, it makes sense to check that the connections in the board and at the socket are tight, test the RCD with its “T” button and inspect the cable and plug.

A type B RCD detects DC leakage currents of any size. It is needed only if the charger has no built-in 6 mA DC detection (RDC-DD). Most modern wallboxes have it, so a type A RCD is enough, and type B is several times more expensive.

No, if it has dynamic load management: a sensor at the supply connection sees how much the household is using and reduces charging when the cooker, water heater and other large appliances are switched on. How much of the connection's power is left for the car is shown by the on-site assessment.

It is not compulsory, but it is a sensible answer to the assembly's question “who is liable?”: the procedure with the residents' assembly. A third-party liability policy costs less than people think.