Device for metering electric power, comprising: - at least one current sensor for supplying a secondary measurement current (Is) representative of a primary current (Ip) flowing in a primary electrical conductor, - an electronic measurement and rectification circuit connected to said at least one current sensor, - a processing circuit connected to the electronic measurement and rectification circuit, - a transmitter, connected to the processing circuit, for transmitting messages in a wireless communications network to an electric power measurement receiver, - an electric current integrating capacitor connected to said at least one current sensor via current rectification means, - voltage threshold detection means, connected to said integrating capacitor, for detecting the exceedance of a predetermined voltage threshold (Svc) across said integrating capacitor, - switching means, controlled by said threshold detection means, for triggering the supply of electric power to said processing circuit and said transmitter with energy accumulated in the integrating capacitor when a voltage (Vc) across said integrating capacitor has exceeded said predetermined voltage threshold (Svc), said processing circuit and said transmitter then transmitting a power message, the device being characterized in that - the processing circuit is designed to increment an accumulated power value by one unit of power calculated as a function of a constant dependent on the charge cycle of said capacitor, with a view to obtaining a total value of electric power, - said power message is representative of the total calculated value of electric power, and - in that the device comprises discharging means (15, 16, 20-24) for discharging said integrating capacitor at the end of the transmission cycle. - at least one current sensor for supplying a secondary measurement current (Is) representative of a primary current (Ip) flowing in a primary electrical conductor, - an electronic measurement and rectification circuit connected to said at least one current sensor, - a processing circuit connected to the electronic measurement and rectification circuit, - a transmitter, connected to the processing circuit, for transmitting messages in a wireless communications network to an electric power measurement receiver, - an electric current integrating capacitor connected to said at least one current sensor via current rectification means, - voltage threshold detection means, connected to said integrating capacitor, for detecting the exceedance of a predetermined voltage threshold (Svc) across said integrating capacitor, - switching means, controlled by said threshold detection means, for triggering the supply of electric power to said processing circuit and said transmitter with energy accumulated in the integrating capacitor when a voltage (Vc) across said integrating capacitor has exceeded said predetermined voltage threshold (Svc), said processing circuit and said transmitter then transmitting a power message, - the processing circuit is designed to increment an accumulated power value by one unit of power calculated as a function of a constant dependent on the charge cycle of said capacitor, with a view to obtaining a total value of electric power, - said power message is representative of the total calculated value of electric power, and - in that the device comprises discharging means (15, 16, 20-24) for discharging said integrating capacitor at the end of the transmission cycle.