An apparatus has an input section arranged to receive values representative of the total instantaneous supply of
electrical current as a function of time from an alternating
voltage supply. Current waveforms comprising sets of values representative of the cyclic waveform of the
electric current supply are obtained. A
delta waveform generator calculates the difference between a current waveform and an earlier current waveform. An
edge detector is arranged to detect an edge or edges in the
delta waveform. An analysis section is arranged to identify at least one appliance load based at least on information on the edge or edges detected by the
edge detector, and to determine the electrical energy consumed by said appliance load. Another apparatus has an input section arranged to receive values representative of the current supplied to an installation, such as a house. A store contains appliance data characteristic of the use of
electricity by each of a plurality of appliances. A processor is arranged to analyse the received values to detect when an appliance is switched on and determine the fractional change in resistance of a heating appliance from the when it is switched on until it reaches its
operating temperature. This information is used to identify what the particular appliance is, and to determine the
electrical energy consumption by that appliance. A utility meter for metering the use of at least one utility supplied to a plurality of appliances is also disclosed. An input section is arranged to receive values representative of the use of a first utility. A store contains appliance data characteristic of the use of utilities by each of a plurality of appliances. A processor is arranged to analyse the received values and to determine information on the use of a second utility by each appliance, based on the received values and appliance data.