POWER INFRASTRUCTURE Rises to other floors
220 volt Dist. board (Grey)
Floor 3
220 volt Dist. board (Grey)
Floor 2
220 volt Dist. board (Grey)
Floor 1
Common neutral path for all 3-phase
Loss/failure of neutral Detail “A”
Riser (normal operation) Load flow
inductive loads. However, since the introduction of frequency-controlled drives which operate at near unity power. A typical example of a current waveform capture with frequency drive connected (Figure 5, top graph) and with the PF isolated (Figure 5, bottom graph). Note: Elimination of zero crossing and much improved waveform. In worse case scenarios, resonances can occur
between the frequency drives and the PF equipment, leading to catastrophic failure of the capacitor banks, sometimes leading to fire. n Recommendation: Switch PF equipment off/on and check PF values at transformer main incomers. If no improvement or change in PF, isolate PF system and record in logbook.
12. Electrical risers Many NHS Hospitals, especially city-based sites, where spatial constraints lead to multi-story buildings and electrical risers form the main method of distribution power. n Key issues: Overloading (1-phase), water ingress from adjacent rising water pipework, and more serious, the loss of the busbar Neutral connection. If this occurs, over voltages will appear on every distribution board with serious consequences of burnt- out electrical equipment. From experience, this normally presents an over voltage on the 1-phase distribution boards in the order of 380 volts depending on the connected load.
n Recommendation: Consider installation of ‘over voltage’ detection devices on new riser busbars and on old ones if isolated for maintenance purpose. Ensure load is well balanced. For resilience, consider dual supplies to each riser via ASCO, Atys and/or simple interconnectors between risers.
13. Commissioning and independent validation
n Key issues: Lack of independent testing and just as important is lack of commissioning. These can compromise patient safety.
n Recommendation: Engage third-party agents or Authorising Engineers to witness tests and maintain comprehensive commissioning records. All variable parameters should be recorded on commissioning records.
Detail “B”
Riser (failed neutral) Load flow
14. ‘As built’ record drawings and documentation
Accurate ‘As-built’ electrical drawings are essential for meeting legal obligations under the Electricity at Work Regulations (EAWR). Regulation 4(2) requires systems to be maintained to prevent danger, while Regulation 29 mandates keeping records to prove compliance. Without accurate drawings, it is impossible to:
n Identify circuits reliably during fixed wire testing. n Isolate circuits safely. n Confirm compliance with BS 7671. n Track system changes effectively.
Their absence increases the risk of error, safety hazards, and non-compliance. n Recommendation: Contact switchboard manufacturers with works order and serial numbers to obtain ‘as-fitted’ drawings. Establish a structured drawing management system to support ongoing compliance and safety.
15. National defects From time to time, design defects are uncovered on electrical equipment and in some cases, inefficiencies in design can sometimes lead to operator errors with the undesirable outcome of an incident in which equipment suffers damage or, in worse cases, injuries or death can occur. Whilst manufacturers should report any defects to their equipment, the end user often raises alerts. The Electricity Networks Association (ENA) operates the NEEDers system, which publishes known defects on its portal. These alerts are circulated via NHS England (formerly NHS estates). Hospital estates teams can access these alerts through the NHS Collaboration Hub which each Trust should have access to.
16. Condition reports Considering the age of the electrical infrastructure in many NHS hospital and the changing characteristics of electrical loads, there are several recommendations. n Recommendation: 5-year risk-based condition reporting complete with budget costs and priority schedule should be completed to include all the elements noted with specific attention on supply capacities, resilience including HV/LV electrical intakes, standby generators, UPS systems, Medical IT Systems, electrical risers, and a sample of final distribution boards.
Eugene Conroy
Eugene Conroy C.Eng MSc FIHEEM MIET is a Chartered Engineer with over 35 years’ experience in high voltage (HV) and low voltage (LV) electrical systems within NHS Acute Healthcare facilities. As a Registered Authorising Engineer (Electrical) with IHEEM, he specialises in critical infrastructure strategy, including HV/LV systems, standby generators, and uninterruptible power supplies (UPS). Eugene has led major projects such as the HV/LV infrastructure integration at London Nightingale Hospital during COVID-19 and has represented NHS Acute Hospital Trusts, the Environmental Agency, and independent data centres across the UK. He has contributed to HTM 06-01, published extensively in Health Estate Journal and IET journals, and presented at IHEEM and IET conferences. Formerly founder and MD of Eta Projects (1998–2022), he is now director of Zendeavour, providing Independent Authorising Engineer services, including Trust strategy planning, 5-Year Condition Reporting, and electrical investigations. Eugene is also dedicated to mentoring and training the next generation of engineers.
380 volt+ Dist. board (Grey)
380 volt+ Dist. board (Grey)
Rises to other floors
380 volt+ Dist. board (Grey)
Figure 6. Electrical fire riser.
January 2026 Health Estate Journal 63
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