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Contact Us 

The SEMO Helpdesk provides an information service for all interested parties, from the industry and market participants to the general public.
The SEMO Helpdesk are available Mon-Fri from 9:00am until 5.00pm.

Queries can be logged online through the link above. To access the Online Helpdesk you will need a password. To request one, please email the Market Helpdesk. If you have a query while you are waiting for your password please choose one of the contact options below.



The SEMO Helpdesk are available Mon-Fri from 8.30am until 5.00pm. We operate a voicemail service if we are unavailable. You can contact us by phone using the numbers below:

  • ROI: 1800 778 111
  • NI: 08000 778 111
  • International: +353 1 237 0468

The Market Operations Hotline  (+353 1 2370573) should only be used for emergency operational issues relating to the next gate window closure. The Hotline is available between:
07:00 – 08:00 for Within-Day 1 (WD1)
08:30 – 09:30 for Ex-Ante 1 (EA1)
10:30 – 11:30 for Ex-Ante 2 (EA2)

Any issues not impacting on the next gate window closure should be raised through the SEMO Helpdesk.


If you are required to fax information to us, our fax numbers are:

  • ROI: +353 1 237 0035
  • NI: +44 2890 707555


If you are required to post information to us please use the relevant address below:

  • SEMO Customer Service
  • 160 Shelbourne Road
  • Ballsbridge
  • Dublin 4
  • Republic of Ireland
  • SEMO Customer Service
  • Castlereagh House
  • 12 Manse Road
  • Belfast BT6 9RT
  • Northern Ireland

If you are visiting us please see below links to a interactive Google maps displaying both our locations:

Castlereagh House, Belfast Interactive Map
The Oval, Dublin 4 Interactive Map

Complaints Procedure

If you are unhappy with the quality of service you have received, you have the right to complain. Please direct these complaints to for the attention of the Market Operations Manager. An escalation process will be initiated and your complaint will be addressed.

As per the Trading & Settlement Code participants may raise a dispute in respect of a Data or Settlement query. For further information please see and review Agreed Procedure 14 – Disputes.

Please view SEMO's full Customer Charter here

SEMO is a joint venture between EirGrid PLC and SONI Limited