Accurately analyzing low-voltage user-side power failure events relies on the real-time and reliable reception of associated reports from metering devices. Thus, this work introduces an ad-hoc micro-power wireless congestion avoidance mechanism which is suitable for the burst reports of multi-user power failure event. The mechanism runs on the top of media access control protocol in the agent coordinator of subnet of an ad-hoc network. It proposed to set a waiting period at the initial stage of reporting the power failure event to gather meters’ packets, following by which forwarding the received packets to the concentrator in a bitmap manner during a transmission period. The waiting period enables the agent coordinator fully adapt to the media competition time required by the burst packets from the metering devices, and thus can reduce the packet loss rate and waiting delay. The simulation results show that the proposed congestion avoidance mechanism can effectively improve the timeliness and reliability of local communication network.