Understanding HTM 06-01: Electrical Services Supply and Distribution in Healthcare

Introduction

In the complex environment of a modern healthcare facility, the reliability of the electrical power supply is not just a matter of convenience—it is a matter of life and death. Healthcare premises are increasingly dependent on electrical power to maintain a safe environment, support sophisticated medical equipment, and enable critical clinical procedures. An interruption in power can seriously disrupt the delivery of healthcare, with potentially serious consequences for patient well-being. This is why the UK's Department of Health and Social Care developed Health Technical Memorandum 06-01: Electrical services supply and distribution (HTM 06-01) — a comprehensive best-practice guide for designing, installing, operating, and maintaining electrical infrastructure in the NHS and other healthcare settings.

What is HTM 06-01?

HTM 06-01 is one of a suite of nine core Health Technical Memoranda, which provide specialist engineering guidance for healthcare buildings. The 2017 edition superseded both parts of the 2007 edition. It combines previous design and maintenance guidance into a single, comprehensive document. The HTM 06 series covers all aspects of electrical services, with parts 06-02 and 06-03 offering more specific safety guidance for low-voltage and high-voltage systems respectively.

The document is designed to be used at all stages of a building's lifecycle, from the design of a new "greenfield" site to modifications of existing installations. It applies to all forms of electrical design work within healthcare premises and provides essential guidance on meeting statutory duties under the Health and Safety at Work etc. Act and the Electricity at Work Regulations.

Key Governance Principle: The Electrical Safety Group

HTM 06-01 establishes a key governance structure for managing electrical safety—the Electrical Safety Group (ESG), a multidisciplinary team with responsibility for all aspects of electrical safety. In many organisations, this group will build on an existing electrical health and safety committee.

The ESG provides a forum where people with a range of competencies can be brought together to share responsibility and take collective ownership for identifying electrical safety issues, assessing risks, and developing and implementing control measures. It ensures that a healthcare organisation's board receives assurance that appropriate expertise and relevant personnel are available to fully implement safety policies. Decisions affecting the resilience, safety, and integrity of electrical systems must not proceed without the agreement of the ESG.

A Risk-Graded Approach to Resilience

One of the most important concepts in HTM 06-01 is the risk-graded approach. The document categorises both clinical risk and business continuity risk to help designers select a proportionate distribution strategy.

Clinical Risk Grades (A to E)

• Risk Grade E (Support services and circulation): includes areas such as offices, waiting areas, and pharmacies. Loss of supply has no immediate clinical impact (excluding statutory lighting and fire systems).
• Risk Grade D (Ambulant care): includes consultation rooms and out-patient areas. Loss of supply causes disruption but does not directly compromise treatment or safety.
• Risk Grade C (General patient care): includes areas where patients may be connected to medical equipment but not for prolonged 24-hour periods. Supply interruption should be limited to less than 15 seconds.
• Risk Grade B (Complex treatment and diagnostics): includes areas such as endoscopy, MRI, accident and emergency, and maternity. Patients may have equipment connected for prolonged periods. Supply should be restored within 15 seconds or, for critical equipment, with no break via a UPS.
• Risk Grade A (Life support or complex surgery): includes operating theatres, critical care, catheterising rooms, and interventional radiology. Any interruption of supply represents a threat to life and demands the highest level of resilience, including UPS-backed supplies for life-supporting equipment.

This grading system is not exhaustive but is designed to prompt essential discussions at all stages of the design process between designers, clinicians, and the ESG.

Designing for Resilience and Power Quality

HTM 06-01 emphasises resilience and power quality throughout the distribution system.

Distribution Strategy: The document provides guidance on designing primary, secondary, and tertiary power supplies. This includes making decisions about the availability of a secondary power supply (SPS) following a primary supply failure. The design must consider the time in which a supply must be restored (e.g., greater than 15 seconds, less than 15 seconds but greater than 5 seconds, or no-break via UPS). For the most critical life-support areas, a no-break (uninterruptible) tertiary supply is recommended.

Power Quality: The document addresses power quality issues like harmonics, which can cause malfunctions and overheating. It provides guidance on designing systems to manage harmonics and ensure a stable, clean supply for sensitive medical equipment.

Protection and Switchgear: The chapter on protection and switchgear highlights the importance of correct device selection, discrimination, and short-circuit ratings to ensure that a fault is isolated as close to the source as possible without affecting other parts of the system.

Electromagnetic Compatibility (EMC) and Earthing: Medical environments are particularly sensitive to electromagnetic interference. The guide offers detailed advice on ensuring EMC and implementing the correct earthing arrangements, including separate protective and clean earths, which are essential for patient safety.

Installation, Commissioning, and Maintenance

The scope of the document extends from initial design to the end of a system's life. The 2017 edition incorporated the separate operational maintenance guide (previously Part B) into the main volume.

Validation and Commissioning: HTM 06-01 requires strict procedures for validation and commissioning. All new installations and modifications to existing systems must be thoroughly tested and documented to demonstrate that they meet the required standards before being handed over for use. This includes insulation resistance tests, earth fault loop impedance tests, and tests on any UPS or generator systems.

Ongoing Maintenance: The maintenance chapter stresses the importance of an effective maintenance strategy to ensure continued reliability. Healthcare organisations must have robust procedures for regular inspection, testing, and maintenance of their electrical systems to mitigate risks of faults or failures. For example, trusts have contracted specialised maintenance services for critical UPS and isolated power supplies to ensure compliance.

The Current Status of HTM 06-01

The 2017 edition of HTM 06-01 remains the current, authoritative version for NHS England. It was published by the Department of Health and is now hosted by NHS England. It has been updated since 2017. While the document itself is not currently listed as being under a major revision, it is reviewed as part of an ongoing process.

An upcoming update (planned for 2026-27) is expected to include revised guidance on the positioning and operation of emergency power-off (EPO) controls, following a coroner's report. The revision will also align with updates to related Health Building Notes.

Conclusion

HTM 06-01 is a cornerstone document for anyone involved in the design, installation, operation, or maintenance of electrical systems in UK healthcare settings. It establishes a risk-based, governance-led approach that is essential for ensuring the safe and reliable power supply on which modern patient care depends. By providing a unified framework covering everything from governance to maintenance, it remains an indispensable resource for ensuring the continuity of care and the safety of patients and staff.

This article provides a summary of key concepts from Health Technical Memorandum 06-01: Electrical services supply and distribution (2017 Edition) and its ongoing status.

Download the full free document here: Health Technical Memorandum 06-01: Electrical services supply and distribution (PDF)

Disclaimer: This article provides a summary of the 'Health Technical Memorandum 06-01: Electrical services supply and distribution' published by NHS England. While efforts have been made to accurately represent the content, please refer to the official document for complete technical details. Final design, specification, and implementation decisions should be made by qualified professionals in accordance with all applicable regulations and standards.