Abstract: A safety device for use in a street lamp, includes a first connection to a power grid (5), second connections to at least two external units (3,4), a first unit (3) of at least two units being adapted to draw current and a second unit (4) of at least two units being adapted to generate a potential difference. The safety device further includes a switch (6) adapted to switch between a first position, in which the first unit (3) is connected to the power line (5) to draw current from the power line, and a second position, in which the second unit (4) is connected to the power line to apply the potential difference to wires of the power line. The safety device further includes a communication system adapted to detect the presence of a safety signal on the power line and to switch the switch (6) to the first position in the event that the safety signal is missing or faulty.

Abstract: A public lighting system includes at least one street lamp (1) of the type including a lighting device (3), a device for converting renewable energy into electric energy (4), and a post switch (6) for alternately connecting either the lighting device (3) or the generator (4) to a power line (5). The lighting system further includes a line switch (70) that switches between a first position, in which the power line (5) is connected to a power grid (8), and a second position, in which the power line (5) is connected to an inverter (71) interposed between the line switch (70) and the power grid (8).