IN Brief:
- Eleven towers on Ireland’s Flagford–Louth 220kV line have been raised by around 2.5 metres while the circuit remained energised.
- Ampjack’s hydraulic system carries the tower and conductor load while additional steel framing is installed within the existing structure.
- The 100km corridor is being refurbished as one of 29 priority transmission projects brought forward by EirGrid.
ESB Networks has begun a major refurbishment of the 100km Flagford to Louth 220kV transmission line, with eleven towers raised by around 2.5 metres using Ampjack technology while the circuit remained energised. EirGrid brought the work forward within a wider programme of priority transmission upgrades intended to strengthen the corridor without creating an additional planned outage during the tower raising phase.
The refurbishment covers towers, foundations and line equipment along the route. It is one of 29 priority transmission schemes accelerated by EirGrid and sits within Ireland’s Price Review 6 investment period, with the completed upgraded line scheduled for energisation between 2030 and 2032.
Keeping the 220kV circuit live changes the engineering sequence considerably. Ampjack installs a modular hydraulic lifting arrangement inside the lattice structure, where it takes the load of the upper tower section and conductors before raising them to the required height. Additional steelwork can then be fitted within the existing tower before the lifting equipment is removed.
Conventional structural work of this scale would normally require the circuit to be taken out of service. On a heavily used transmission route, that can force electricity onto other circuits and reduce the operating margin available if another network asset becomes unavailable. The live line method preserves the route while the tower geometry is altered, although other elements of the wider refurbishment may still require conventional outages.
Raising the existing structures also avoids complete tower replacement where additional electrical clearance can be achieved through modification. Increasing tower height by approximately 2.5 metres provides greater conductor clearance while retaining the principal structure and route, although the condition and capacity of foundations still have to be assessed as part of the programme.
ESB Networks is delivering the work with ESB Engineering and Major Projects, contractor Circet and Canadian specialist Ampjack. The method has previously been used on transmission networks elsewhere, but Flagford to Louth is its first deployment in Ireland.
Ireland’s wider network programme is expanding at the same time as demand rises from housing, transport and industry and larger volumes of renewable generation need access to the system. Existing transmission corridors therefore have to carry electricity while reinforcement, uprating and replacement work takes place around them.
That operating constraint makes outage duration a practical limit on how quickly an established network can be upgraded. New lines can add capacity, but refurbishment remains important where routes, substations and rights of way are already established. Reducing the amount of work that requires a circuit to be isolated gives operators more options for sequencing several projects across the same system.
Tower height is governed in part by the electrical clearance required between conductors and the ground, roads, vegetation and other infrastructure below the line. Conductor sag also changes with temperature and loading, so the required clearances have to be preserved throughout the circuit’s operating range rather than at one static condition.
The lifting method therefore requires detailed structural and electrical planning before the hydraulics are installed. The tower must continue to carry conductor tension and environmental loads during the modification, while temporary lifting equipment has to transfer the structural load safely as the new framing is introduced. Working inside an energised corridor also imposes strict control of approach distances, work zones and coordination between the network operator, engineering team and contractor.
EirGrid accelerated the Flagford to Louth scheme because the route forms part of the transmission infrastructure linking the Midlands, North-East, West and North-West with the wider national network. The eleven raised towers represent an early engineering milestone within a longer programme of work across the route.
Further refurbishment of structures, foundations and line equipment will continue before the upgraded line reaches its planned 2030 to 2032 energisation window. Live line tower raising cannot remove every outage from that programme, but it allows one difficult structural operation to proceed without sacrificing an operating 220kV circuit while the work is under way.
