ESB Networks says more than 300 homes and businesses have been left without power in Killarney.
According to the utility's PowerCheck app, the fault in Coolcorcoran was reported at 6.29pm.
Three hundred and two customers have been left without electricity.
PowerCheck had indicated power should be restored by quarter past midnight but it's now indicating it may be later.
For updates go to http://https://www.esb.ie/esb-networks/powercheck/index.html