EirGrid must balance electricity supply and demand at all times to keep Ireland’s power system stable and secure. Faults on the transmission system that can be caused by, for example, adverse weather conditions, can result in severe voltage dips that propagate across wide areas of the power system. These faults are normally isolated extremely quickly due to the response of high-speed transmission protection equipment, allowing the voltage to recover to normal operating range within 100 milli-seconds (ms).
These fault events are common in all power systems, and most users of the power system have the capability to ‘ride-through’, i.e. not trip-off, during these transient events with normal generation and consumption levels restored once the fault is cleared.
EirGrid has identified a risk to grid stability arising from the collective response of most data centres to fault events occurring on the transmission system. When a fault event occurs, most data centres, even those remote from the fault, automatically and near instantaneously significantly reduce consumption from the grid and switch to their own, temporary, back-up sources of supply and do not return to their pre-fault level of demand for an extended period. The simultaneous disconnection of a large volume of demand from the power system can create sudden imbalances between supply and demand, which EirGrid is managing in real time, and therefore represents both a significant risk to the security of the system and operational challenges for EirGrid.
The risk to the system is currently being managed through a range of mitigation actions. However, based on recent actual demand utilisation increases, the system has moved closer to the point at which these mitigation actions will be exhausted due to the continued growth of demand that does not have FRT capabilities. This is increasing the material risk to system security and urgent action is required to address the FRT challenge. In the event of a fault, the risk to the security of the system may be to the degree that power outages may occur throughout the system in a way that cannot be managed or controlled by the TSO. This would risk impacting all customers, domestic and non-domestic and essential services. EirGrid and SONI note in their Joint information paper that, based on their analysis of increased data centre demand scenarios, if not mitigated, these scenarios would expose all consumers in Ireland and Northern Ireland to the risk of a significant system incident.
EirGrid has proposed a modification (MPID 345) to the Grid Code which would introduce new requirements for transmission-connected demand facilities aimed at resolving this issue. The CRU invited representations on EirGrid’s proposals in April 2026. The CRU is now inviting further representations from stakeholders on a number of topics relating to MPID 345, including an information paper from EirGrid setting out their assessment of alternative options, reports from the CRU’s technical advisors, information on the impact that EirGrid’s proposals may have on stakeholders’ businesses, information on the impact of ongoing operational measures to manage FRT risk, and views on a proposed change by EirGrid to the originally proposed Compliance and Derogation Framework. All stakeholder views will be reviewed and considered by the CRU.
Grid Code Modification MPID 345 and Compliance and Derogation Framework: Request for further representations
EirGrid must balance electricity supply and demand at all times to keep Ireland’s power system stable and secure. Faults on the transmission system that can be caused by, for example, adverse weather conditions, can result in severe voltage dips that propagate across wide areas of the power system. These faults are normally isolated extremely quickly due to the response of high-speed transmission protection equipment, allowing the voltage to recover to normal operating range within 100 milli-seconds (ms).
These fault events are common in all power systems, and most users of the power system have the capability to ‘ride-through’, i.e. not trip-off, during these transient events with normal generation and consumption levels restored once the fault is cleared.
EirGrid has identified a risk to grid stability arising from the collective response of most data centres to fault events occurring on the transmission system. When a fault event occurs, most data centres, even those remote from the fault, automatically and near instantaneously significantly reduce consumption from the grid and switch to their own, temporary, back-up sources of supply and do not return to their pre-fault level of demand for an extended period. The simultaneous disconnection of a large volume of demand from the power system can create sudden imbalances between supply and demand, which EirGrid is managing in real time, and therefore represents both a significant risk to the security of the system and operational challenges for EirGrid.
The risk to the system is currently being managed through a range of mitigation actions. However, based on recent actual demand utilisation increases, the system has moved closer to the point at which these mitigation actions will be exhausted due to the continued growth of demand that does not have FRT capabilities. This is increasing the material risk to system security and urgent action is required to address the FRT challenge. In the event of a fault, the risk to the security of the system may be to the degree that power outages may occur throughout the system in a way that cannot be managed or controlled by the TSO. This would risk impacting all customers, domestic and non-domestic and essential services. EirGrid and SONI note in their Joint information paper that, based on their analysis of increased data centre demand scenarios, if not mitigated, these scenarios would expose all consumers in Ireland and Northern Ireland to the risk of a significant system incident.
EirGrid has proposed a modification (MPID 345) to the Grid Code which would introduce new requirements for transmission-connected demand facilities aimed at resolving this issue. The CRU invited representations on EirGrid’s proposals in April 2026. The CRU is now inviting further representations from stakeholders on a number of topics relating to MPID 345, including an information paper from EirGrid setting out their assessment of alternative options, reports from the CRU’s technical advisors, information on the impact that EirGrid’s proposals may have on stakeholders’ businesses, information on the impact of ongoing operational measures to manage FRT risk, and views on a proposed change by EirGrid to the originally proposed Compliance and Derogation Framework. All stakeholder views will be reviewed and considered by the CRU.
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