37 Installation, maintenance and repair services of electrical apparatus and instruments for transporting, distributing, connecting, transforming, accumulating, regulating, filtering, measuring, signalling, controlling or monitoring electricity, interrupters, control mechanisms, isolating switches and switchgears, isolating switches or selector switches used with high and medium voltage currents, maintenance and adjustment of electrical apparatus and instruments for transporting, distributing, connecting, transforming, accumulating, regulating, filtering, measuring, signalling, controlling or monitoring electricity, interrupters, control mechanisms, isolating switches and switchgear, isolating switches or selector switches used with high or medium voltage currents; assistance and consultancy regarding installation services pertaining to electrical apparatus and instruments for transporting, distributing, connecting, transforming, accumulating, regulating, filtering, measuring, signalling, controlling or monitoring electricity, interrupters, control mechanisms, isolating switches and switchgear, isolating switches or selector switches used with high and medium voltage currents