A disaggregation apparatus for identifying an appliance in an electrical network, which comprises multiple appliances (3, 4, 5) and which is powered by a power source, the disaggregation apparatus comprising: - a voltage meter for measuring a first change in a mains voltage delivered to the appliances (3, 4, 5) of the electrical network, while an operational state of an appliance is modified, - a controller for switching a switchable load, other than the appliance, the switchable load having a known resistance, wherein the voltage meter is adapted to measure a second change in the mains voltage delivered to the appliances (3, 4, 5) of the electrical network, while the switchable load is switched, - an appliance determination unit for determining a charcteristic of the appliance, of which the operational state has been changed, based on the measured first change in the mains voltage, the measured second change in the mains voltage and the resistance of the switchable load, and for determining the appliance by comparing the determined characteristic with characteristics stored in a memory, wherein the appliance determination unit is adapted to determine a change (ΔY) in a total admittance of the electrical network of the appliances (3, 4, 5) from the measured first change in the mains voltage and from a ratio of a voltage (Vo) supplied by the power source and an impedance (Zo) of the electrical network, wherein the ratio is determined from the measured second change in the mains voltage and the resistance of the switchable load, and to determine the appliance, of which the operational state has been changed, based on the determined change (ΔY) in total admittance, wherein the admittance determination unit is adapted to determine from the measured first change in the mains voltage a first change (Δ 1 (1/V)) in the reciprocal mains voltage (1/V), and to determine the change (ΔY) in the total admittance depending on the product of the ratio and the first change (Δ 1 (1/V)) in the reciprocal mains voltage (1/V), wherein the admittance determination unit is adapted to determine from the measured second change in the mains voltage a second change (Δ 2 (1/V)) in the reciprocal mains voltage (1/V), and to determine the ratio depending on the product of the the resistance of the switchable load and the second change (Δ 2 (1/V)) in the reciprocal mains voltage (1/V). - a voltage meter for measuring a first change in a mains voltage delivered to the appliances (3, 4, 5) of the electrical network, while an operational state of an appliance is modified, - a controller for switching a switchable load, other than the appliance, the switchable load having a known resistance, wherein the voltage meter is adapted to measure a second change in the mains voltage delivered to the appliances (3, 4, 5) of the electrical network, while the switchable load is switched, - an appliance determination unit for determining a charcteristic of the appliance, of which the operational state has been changed, based on the measured first change in the mains voltage, the measured second change in the mains voltage and the resistance of the switchable load, and for determining the appliance by comparing the determined characteristic with characteristics stored in a memory,