22OCT

CRU makes Irish sites ride through dips

2 min read

16:40UTC

Ireland's energy regulator approved grid-code change MPID 345, which requires transmission-connected demand facilities to stay connected through brief voltage dips from about 27 October.

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Key takeaway

Irish transmission-connected data centres must ride through voltage dips from late October or hold an EirGrid derogation.

Ireland's Commission for Regulation of Utilities (CRU) approved grid-code change MPID 345 on 22 September, according to a summary by the law firm Arthur Cox⁠¹. It requires transmission-connected demand facilities to stay connected through brief voltage dips ("fault ride-through") and takes effect about 27 October. Transmission-connected data centres that do not comply must request a derogation, a time-limited exemption, from EirGrid, Ireland's grid operator, before then.

The rule builds on the fault-ride-through demand-curtailment procedure EirGrid issued to data-centre customers in June, which capped how much load the grid could afford to lose at once. MPID 345 moves that requirement from an operating procedure into the grid code itself.

Deep Analysis

In plain English

When a power line fails or lightning strikes, the voltage on the electricity grid can drop for a fraction of a second. Data centres, the large buildings full of computers that run online services, often react by disconnecting and running on their own batteries. In Ireland data centres use so much electricity that if many disconnect at once, the whole grid can be thrown off balance. So the energy regulator has approved a rule that sites connected directly to the high-voltage transmission grid must stay connected through these short dips. The rule starts around 27 October. Transmission-connected data centres that cannot meet it in time must ask EirGrid, which runs the national grid, for a temporary exemption.

Deep Analysis

Root Causes

Data centres protect their computers by switching to batteries or generators when grid voltage dips. Each site doing so is sensible on its own; many doing it together remove a large block of demand at once, which can unbalance the system.

Ireland's exposure is unusually high because data centres take about a third of national electricity, much of it concentrated around Dublin. Behaviour that barely registers on larger grids threatens stability on Ireland's.

What could happen next?

Consequence
Data centres that do not comply must request a derogation from EirGrid before the rule takes effect around 27 October.
Risk
Sites refused a derogation may need equipment changes to keep their connection.

Source Landscape

This story draws on neutral-leaning sources

Primary parallel: the Commission for Regulation of Utilities reopened large-load connections in early 2026 on condition that new data centres reach 80% renewable supply within six years and carry 100% on-site backup. Ireland again regulates data centres through the terms of their grid connection rather than through planning law.

Counter-parallel: South Korea is writing a similar ride-through duty for AI data centres but is still arguing over whether projects under way should be exempt. Ireland applies its rule to existing transmission-connected sites and handles exceptions one by one through derogations.

Consensus view: EirGrid and SONI, the Northern Ireland operator, set out the risk in June: their procedure caps instantaneous demand loss at 900 MW and warns of imbalance above 1,150 MW. When many data centres switch to backup at once during a fault, the grid loses that demand in an instant, and MPID 345 makes staying connected a condition of the connection.

Counter-view: Arthur Cox's summary puts the weight on process. Non-compliant transmission-connected sites must request a derogation from EirGrid before the start date, so the first effect may be to sort the fleet into compliant and exempted sites rather than to change equipment.

Key tension: How many derogations EirGrid grants, and for how long, which decides whether the rule reaches the existing fleet or mainly new connections.

Sources:Arthur Cox·Commission for Regulation of Utilities (Ireland)·Commission for Regulation of Utilities (Ireland)

Mentions:CRU →EirGrid →Ireland →Northern Ireland →SONI →South Korea →

First Reported In

Update #17 · Stalled power line cuts A$140m from NEXTDC guidance

Arthur Cox· 22 Oct 2026

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Written with AI from Lowdown's published reporting. Not individually reviewed by an editor. Editorial standards.