The safety circuit includes a safety switch or a series circuit of safety switches, which includes an input for an electrical safety circuit signal as well as an output, in which the electrical safety circuit signal being supplied to the input is present when all the safety switches are closed. The safety circuit also includes a cable including an optical fiber as well as a transmitter circuit for the optical signal, the output of which circuit is connected to the cable including an optical fiber. The input of the transmitter circuit is connected to the output of the aforementioned safety switch or of the series circuit of safety switches, and the transmitter circuit is configured to transmit in the optical fiber of the cable the safety circuit signal that is present in the output of the safety switch or of the series circuit of safety switches.