FEL Group were engaged and challenged by a leading telecommunications provider, to find a solution to their operational issue.

The issue, as so often experienced, was to formulate a strategy and solution to generate extra capacity in a fully populated live Datacentre facility, whilst still keeping it fully operational.

At this particular location, the site’s power distribution system had reached its absolute maximum Agreed Supply Capacity (ASC) from the local Distribution Network Operators (DNO) thereby preventing any further growth on the existing site footprint.

This particular site also plays a significant role in their overall strategy, a “core backbone” site, whereby further planned growth is destined and envisaged for many years to come.

To allow the increase of the ASC and ultimately upgrading the site to Tier 3 classification, the primary electrical infrastructure needed to be significantly modernised. This together with a catastrophic failure of the site’s back up generating plant, became the catalyst for the customer to instigate this project.

The new project to upgrade the generators and the site power distribution systems has gone extremely well. FEL Group have progressed well and everything has been completed as per our required standards and to the correct specification. The meters were installed, and final testing was carried out. FEL Group have officially handed the site back with the new generators running and live on our network.

Tony Evans, Regional Power Project Engineer, Technical Site Engineering



Major electrical project


International television & telecommunications company




28 weeks

FEL Group were engaged to prepare a design to supply and install a 2000kVA main distribution system with N+1 resilience.

Tier 3 classification also required concurrent maintainability and “no break” on load testing of the generating plant, utilising G59 short term paralleling controls.

The upgrade of the distribution system began with the installation of a new 11kV substation, from which a client’s HV supply was installed to supply a new 11kV extendable switchboard. The new switchboard in turn supplies 2 new 2000kVA air cooled transformers arranged in N+1 configuration. The final connection to the main LV switchboard was provided by a cast resin bus bar system.

In the event of mains supply failure to the site, support is provided by 2no. 1250kVA diesel generators, with the additional facility for a third set to be installed to enable further site expansion. The diesel generating plant are configured with a paralleling control system to allow the generating plant to be either tested or taken off line for regular maintenance, without any disruption in the power to the site. A facility is also incorporated within the distribution system to connect load banks for generator testing and connection of temporary generators should they need to be taken out of service for an extended period.

Associated works included:

  • Preparation and submission of planning application to local Authority including extensive surveys.
  • All construction and builders work including provision of concrete bases and maintenance access to generator plant.
  • Extension of existing SCADA monitoring system to provide fault annunciation to the customers UK central monitoring station.
  • Modifications to the existing distribution system to enable seamless integration of the new power distribution system.
  • Modification/Enhancement of the existing on-site Fire, gas suppression, CCTV and security systems.

The challenges

Prior to commencing on any significant projects and as part of our due diligence, we carry out a ground radar survey of the whole site. This helps us to identify and locate any buried services and potential issues; on this particular project, this process revealed the presence of a considerable number of relatively shallow, previously unknown, surface and foul drainage services.

After consultation with our structural engineers and project team, our options were considered. We concluded that the proposed location of the generators would exert high levels of ground pressure on the drainage services, which would potentially result in failures at a later date.

Given that these drainage services would be inaccessible post the installation of the generators and associated fuel tanks, any access to carry out any repairs would be extremely difficult. To significantly reduce this risk, we elected to install a number of mini-piles, we then connected and linked the same with pile cappings.

Finally, we supported all the above with ground galvanised steel grillage, upon which both the generators and fuel tanks were situated.

The crucial result being that all the generator weight was bridged over, rather than on top of the drains.

Managing change requests without delays to agreed programme.

Midway through the project, our customer revised the original design brief and requested that we incorporate automatic controls to assist in the isolation of the generator switchboard and main LV switchboard.

This resulted in the incorporation of an N+1 PLC’s control system, which automatically controls both the opening and closing of designated circuit breakers to ensure seamless support to essential services.

Throughout this project as a whole and despite the unforeseen challenges faced, FEL Group were pleased to ensure there was NO delay to the agreed programme