Devices connected to the low-voltage power grid generate disturbances that can cause malfunctions and thermal stress in the equipment connected to the mains or interference on power line communications. Currently, there is no normative method to measure the disturbances in the low voltage grid for the CISPR Band A (9-150 kHz). The Annex C of IEC 61000-4-30 Ed. 3 standard suggests three non-normative measurement methods, one of them is the method described in Annex B of IEC 61000-4-7for the 2-9 kHz range. This paper describes a proposal to adapt this method to the CISPR Band A: the RM-A method. This method aims at obtaining results of similar amplitude, with a higher granularity in the time domain, and avoiding a high computational burden due to the broader frequency range. Moreover, a more accurate detection of high-level short impulsive disturbances is obtained. The performance of the RM-A method is evaluated using a data set of recordings from the low voltage grid. The proposed method has been presented to IEC SC77A/WG9 as a first stage of a more complex method, for its potential inclusions in the IEC 61000-4-30 Ed. 4.