Do I need special protection against overvoltage for the BUS line?

It is crucial to protect the system from the effect of lightning using surge suppressors (SPD Surge Protective Devices). As a general rule, protection from the supply side should be implemented with a Class I SPD downstream from the electricity meter, an SPD Class II after the circuit breaker, and an SPD Class III on the power supply input. If there is a dialler, you should also install an SPD on the telephone line.