Abstract: A method of remotely determining an impedance of an earth connection (142) of a first electrical equipment (122) connected to a power supply network (300). The method comprises receiving (606), from a first measurement node (302) connected to the first electrical equipment, a first value of an insulation impedance of the power supply network and receiving (612), from a second measurement node (304) connected to the power supply network, a second value of an insulation impedance of the power supply network. The method further comprises calculating (614) the impedance of the earth connection of the first electrical equipment using the first value of the insulation impedance of the power supply network, the second value of the insulation impedance of the power supply network and a known impedance value of an earth connection (144) of the second measurement node.

Abstract: A method of remotely determining an impedance of an earth connection (142) of a first electrical equipment (122) connected to a power supply network (300). The method comprises receiving (606), from a first measurement node (302) connected to the first electrical equipment, a first value of an insulation impedance of the power supply network and receiving (612), from a second measurement node (304) connected to the power supply network, a second value of an insulation impedance of the power supply network. The method further comprises calculating (614) the impedance of the earth connection of the first electrical equipment using the first value of the insulation impedance of the power supply network, the second value of the insulation impedance of the power supply network and a known impedance value of an earth connection (144) of the second measurement node.

Abstract: A wet mate optical connector in combination with a wave division multiplexer, there being a plurality of input fiber optic cables on an input side of the multiplexer and a fiber optic cable on an output side of the multiplexer connected for providing multiplexed optical signals from the input cables to the wet mate connector.

Abstract: An optical amplifier comprising: an optical coupler configured to receive a communication signal and couple said communication signal to an optical connector of a doped optical fibre; and at least one electrical to optical data converter connected to the optical coupler to provide pump radiation thereto.