Outage Information

How we plan for generator and transmission outages, including testing and maintenance.

Generation Outage

As part of maintaining the grid, we develop and implement a Generation Outage Plan. Power stations are sometimes unavailable due to maintenance or other reasons. This plan ensure that these planned outages are well coordinated.  

It takes into account:

  • Security of supply in Ireland and Northern Ireland
  • Economic operation of the power system
  • The maintenance and resource needs of generators 

Find annual outage plans on the TSO Responsibilities page of the SEM-O website, under Outages.

Generation Outage Requests

Generators can send outage requests to us using the Generator Outage Request Form. This covers new and changed outages, including short-term requests.

The forms for Generator Outage requests are below.

Short-Term Maintenance Outages (STMOs)

STMOs are usually less than 48 hours. They're typically carried out overnight or at the weekend.

For STMO requests, we assess the planned network configuration, forecast load, and capacity margin for the outage time. 

STMO requests should be made at least five working days before the outage start time and date.

Generator HV Plant Outages

For an outage scheduled on the Committed Outage Programme and Transmission Outage Programme, please complete a Transmission Outage Request Form. Please make requests as early as possible, at least ten working days before the outage start date.

The start and end dates must be in line with the Transmission Outage Programme.

For outages not in these programmes, we require at least three weeks’ notice to assess their feasibility. 

Generator Outage Publications

A weekly All-Island Outage Plan covering the next 16 weeks is published here. The report consists of two worksheets. The first sheet shows the outages graphically at a daily level. The second worksheet shows the start and finish times and dates of the outages. Outages are represented with an abbreviation in the files - “S” represents a Scheduled Outage and “F” represents a Forced Outage.

Transmission Outages

Our Transmission Outage Programme plans times when transmission infrastructure (lines, cables and transformers etc.) will be out-of-service for maintenance or capital works.

Transmission Outage Requests

Transmission connected customers can make outage requests using the Transmission Outage Request Form. Please make requests as early as possible, at least three weeks before the planned outage. 

This gives us time to conduct relevant studies and for ESBN to assign Network Technician resources. Works requiring an EI must be submitted at least five weeks in advance.

Outages Affecting Generator Connections

We collect information on generator transformer and house transformer outage requirements for the coming year. 

This feeds into the development of the Transmission Outage Program. Once this is complete, we give generators details of all transmission outages affecting them.

During specific transmission outages, we notify a station that a generation unit’s availability as defined in the Grid Code will be different from the outturn availability in the transmission dispatch system.

Outturn Availability

The below decision paper covers the process for calculating outturn availability.

The documents that follow give more information for the current outage season.

​Joint Outage Transformation Programme

Outage management is a critical and challenging space.

An exceptional scale and pace of change in this area is necessary to deliver the new transmission infrastructure required to achieve our electrification and renewable energy targets by 2030. 

EirGrid and ESB Networks have been working closely on this as a priority and our Joint Outage Transformation Programme (JOTP) is under way. 

This statement sets out the various interventions that the JOTP is focused on to increase outage availability, maximise utilization and effectiveness of outages.