Apparatus and instruments for measuring, signalling, monitoring, conducting, commutation, transformation, accumulation, regulating and control of electricity, namely, ammeters, voltmeters, watt meters, phi meters, phase meters, frequency meters, power meters, commutators, converters, transformers, [ relays, sequence meters, temperature indicators, switches, two-way switches, inverters, chronothermostats, telerupters, ] hour meters, [ pulse counters, variators, resistors, stabilised feeders, b...