More than 500 homes across Weymouth and Dorchester have lost power.
A spokesman for Scottish and Southern Electricity Networks (SSEN) said: "We apologise for the loss of supply. We currently have a fault affecting the areas listed.
"Our engineers are on site working to get the power back on as quickly as they can. If you need more information, please call us on 0800 072 7282 and quote reference 'CC7117'."
The fault was reported at 4.03pm and restoration is expected at 6pm today.
The power cut is affecting homes in the DT2 and DT3 postcodes.
Engineers from Scottish and Southern Electricity Networks (SSEN) were made aware of a fault this afternoon affecting the Sutton Poyntz, Osmington and Ringstead areas.
A spokesman for Scottish and Southern Electricity Networks (SSEN) added: "This is affecting 515 properties in the area and is due to third party damage to an underground cable.
"Our engineers are on site and are expecting to restore power to the majority of customers by 6pm this evening.
“We would like to apologise to our customers for the inconvenience and thank them for their patience as our engineers work to restore their power as quickly and as safely as possible.”
There are reports that power has now been restored in Sutton Poyntz.
The are 46 known affected areas are: