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 8.30am 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

SEMO is a joint venture between EirGrid PLC and SONI Limited