T4 EU 2C 2-gang WiFi+RF smart light switch (single-live-wire, works without neutral) (R2, white)

Usually, only the phase wire is connected in plain light switches. As a result, replacement is only required with light switches or switch relays that do not require a neutral wire. These are also called one or two wires (incoming phase + outgoing phase).

If possible, use switches that require zero because they are more stable and compatible with any lamp and consumer. These are also called two or three wires (zero + incoming phase + outgoing phase).