A gas turbine engine 10 is provided with electrical harness rafts 200 comprising electrical conductors embedded in a rigid composite material. The rafts 200 are used to transport electrical signals (which may be, for example power and/or control signals) around a gas turbine engine. Rafts 200 may be connected together and to other components using flexible cables, that may help to accommodate relative movement of the rafts 200, for example through vibration. The rafts 200 are lighter, more compact, and more convenient to handle than conventional electrical harnesses. The rafts 200 may provide a convenient and secure mounting surface for other components/systems of a gas turbine engine, such as EECs and/or fluid pipes.