What is IEC 60364-7-710 and how does it apply to UK hospital electrical installations?

IEC 60364-7-710 is the international standard for medical locations, adopted in the UK as Part 7 Section 710 of BS 7671:2018+A4:2026. It defines the specific requirements for electrical installations in areas of hospitals, clinics, dental surgeries, and medical practices where medical electrical equipment is used on patients. The standard classifies medical locations into Group 0, Group 1, and Group 2 based on the intended use and the risk to the patient from a loss of electrical supply, and specifies protection measures appropriate to each group. All new UK hospital electrical installations and major refurbishments must comply with Section 710.

What is a Group 2 medical location and what are the electrical requirements?

A Group 2 medical location is a space where medical electrical equipment is used in direct contact with the patient's heart (e.g. cardiac catheters) or where interruption of supply could be immediately life-threatening. Examples include operating theatres, cardiac catheter labs, intensive care units (ICUs), and neonatal intensive care units (NICUs). Group 2 locations require: an IT system (isolated earth system) with insulation monitoring; local Insulation Monitoring Device (IMD) alarm panels; essential supply changeover within 0.5 seconds for critical circuits; additional equipotential bonding of all metalwork within the patient environment; and minimum socket outlet requirements within reach of the patient zone.

What is an IT system (isolated power supply) in a hospital context?

An IT system in a hospital is an Isolated Terra (IT) electrical distribution system in which neither pole of the supply is connected to earth. This is achieved using a medical isolation transformer. Because no conductor is intentionally earthed, the first insulation fault to earth does not cause a short-circuit or trip a protective device — the supply to life-critical equipment continues uninterrupted. An Insulation Monitoring Device (IMD) continuously measures the insulation resistance of the system and sounds an alarm if it falls below 50 kΩ (for operating theatres) or 100 kΩ (for other Group 2 locations), prompting maintenance to investigate and rectify the fault before a second fault can cause a supply interruption.

What does HTM 06-01 require for hospital essential services?

NHS Health Technical Memorandum 06-01 (HTM 06-01) requires that hospital essential electrical services are maintained by emergency generator sets in the event of a mains supply failure. Essential services are categorised as: Category 1 (no-break supply, maximum 0.5 second changeover, for life support, operating theatre lighting, and critical monitoring equipment), Category 2 (short-break supply, maximum 15 seconds, for emergency lighting, general theatre power, and ward nurse call systems), and Category 3 (delayed supply, maximum 60 seconds, for general essential services). Separate essential services distribution boards must be provided for each category.

What RCD requirements apply to hospital electrical installations?

Standard 30mA RCDs as used in domestic and commercial premises are generally not used in Group 2 medical locations because they would disconnect supply to life-critical equipment on a first earth fault. Instead, Group 2 locations use IT systems with insulation monitoring as described above. Where RCDs are used in Group 1 locations or non-patient areas, they must be 30mA Type A or Type B (for equipment with DC components) in accordance with Section 710 of BS 7671. Medical grade RCDs with lower nuisance tripping characteristics may be specified by the design engineer. RCDs are required on all socket outlet circuits in non-Group 2 areas per Regulation 411.3.3 of BS 7671.

Who is qualified to design and install hospital electrical systems in the UK?

Hospital electrical installations require a combination of BS 7671 competence and specialist knowledge of Section 710 and HTM 06-01. Designers should hold an IET membership or similar professional qualification and be familiar with Healthcare Premises Design guidance. Installers should be registered with NICEIC, NAPIT, or an equivalent scheme and have demonstrable experience in healthcare projects. All installations must be certified to BS 7671 on completion. Hospitals should also appoint a qualified Authorising Engineer (Electrical) as required by HTM 06-01 to manage the electrical safety of the estate.

What earthing arrangements are required in the patient environment?

In Group 1 and Group 2 medical locations, supplementary equipotential bonding must be applied within the patient environment (the area within 1.5 metres horizontally and 2.5 metres vertically of the patient's position). All simultaneously accessible conductive parts, including electrical equipment frames, bed frames, metallic pipework, radiators, and structural steelwork, must be connected to a patient environment equipotential bonding bar. The bonding conductors must meet the minimum cross-sectional area requirements of BS 7671 Regulation 544.1. This bonding reduces the risk of dangerous potential differences appearing across the patient during fault conditions.

HEALTHCARE ELECTRICAL GUIDE

Hospital Electrical Installation UK: Healthcare Systems Guide

The complete technical guide to hospital and healthcare electrical installation in the UK — covering IEC 60364-7-710, BS 7671 Section 710, Group 1 and 2 medical locations, isolated power supplies, insulation monitoring, essential services, HTM 06-01, and patient environment earthing.

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15 min readUpdated 2026-05-18Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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Key Takeaways

1Hospital electrical installations in the UK must comply with BS 7671:2018+A4:2026 Part 7 Section 710, which implements the requirements of IEC 60364-7-710 for special installations and locations — medical locations.
2Medical locations are classified as Group 0 (no medical electrical equipment applied to the patient), Group 1 (applied parts used externally), or Group 2 (applied parts used in life-critical applications such as operating theatres and cardiac care units).
3Group 2 locations require IT systems (Isolated Terra systems) with insulation monitoring devices (IMDs) to allow early warning of a first earth fault without interrupting supply to life-support equipment.
4NHS England's Health Technical Memorandum HTM 06-01 provides authoritative design and management guidance for healthcare electrical services, supplementing the statutory requirements of BS 7671 and the Electricity at Work Regulations 1989.
5Essential services in hospitals must be maintained by automatic changeover to generator power within 0.5 seconds for Category 1 circuits (life support) and 15 seconds for Category 2 circuits (emergency lighting, operating suites), in accordance with HTM 06-01.

01 · Healthcare Electrical Guide

Hospital Electrical Installation in the UK

Hospital and healthcare electrical installation is among the most technically demanding and safety-critical disciplines in the UK electrical industry. The combination of vulnerable patients, life-critical equipment, 24/7 operational requirements, and complex regulatory obligations makes healthcare electrical engineering a distinct specialism. Errors in design, installation, or maintenance can directly endanger patient lives.

The primary technical standard is Section 710 of BS 7671:2018+A4:2026, which implements IEC 60364-7-710 for medical locations. The primary management and design guidance is NHS England's Health Technical Memorandum HTM 06-01. These documents must be read together — BS 7671 provides the statutory minimum requirements, while HTM 06-01 provides the additional engineering guidance appropriate for NHS facilities.

Scope: Section 710 applies to hospitals, clinics, medical and dental practices, healthcare centres, and any location where medical electrical equipment is used in direct contact with patients, including private facilities and veterinary practices.
Statutory obligation: The Electricity at Work Regulations 1989 apply in full to all healthcare premises. NHS facilities also have obligations under the Health and Safety at Work etc. Act 1974 and the Care Quality Commission (CQC) registration requirements, which include electrical safety.
Professional roles: NHS Estates departments appoint an Authorising Engineer (Electrical) under HTM 06-01. This person holds overall technical authority for the electrical safety of the estate and authorises Appointed Persons and Competent Persons to carry out work on the electrical installation.

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02 · Healthcare Electrical Guide

Class 1 and Class 2 Medical Locations

IEC 60364-7-710 and BS 7671 Section 710 classify medical locations into groups based on the nature of the medical activity carried out and the consequence to patient safety of an electrical supply interruption or fault.

Group 0 locations: Medical electrical equipment is not used in contact with the patient, or only equipment not classified as an applied part is used. Examples: waiting rooms, hospital corridors, administrative areas. Standard BS 7671 requirements apply with no special Section 710 measures beyond general commercial requirements.
Group 1 locations: Applied parts are intended for external use only, or internal use in parts of the body other than the heart. Examples: examination rooms, physiotherapy rooms, radiology (X-ray), general wards, dental surgeries. 30mA RCDs are required on all socket circuits within the patient environment. IT systems are recommended but not mandatory.
Group 2 locations: Applied parts are intended for procedures where interruption of supply could be immediately life-threatening. Examples: operating theatres, cardiac catheter labs, ICUs, NICUs, anaesthetic rooms. IT systems with insulation monitoring are mandatory. Essential supply changeover within 0.5 seconds for life-critical circuits is required.

The group classification must be determined by the healthcare client and clinical team during the design stage, documented in a medical location schedule, and agreed with the Authorising Engineer before installation commences.

03 · Healthcare Electrical Guide

IEC 60364-7-710 and BS 7671 Section 710

Section 710 of BS 7671:2018+A4:2026 sets out specific requirements that supplement or modify the general requirements of the rest of the standard for medical locations. Key requirements include:

Regulation 710.312.2 — Essential supply: Final circuits for life support systems, operating theatre lighting, and surgical luminaires must be supplied by essential services with automatic changeover not exceeding 0.5 seconds (Category 1). Other essential circuits must change over within 15 seconds (Category 2) or 60 seconds (Category 3).
Regulation 710.413 — IT systems for Group 2: In Group 2 locations, each IT system must serve only one Group 2 room (or small group of rooms), must include an Insulation Monitoring Device, and must have a local alarm panel clearly visible to clinical staff. The IMD must raise an alarm at 50 kΩ insulation resistance for circuits up to 63A.
Regulation 710.514.1 — Documentation: A schedule of medical locations, including their group classification and the protective measures applied, must be prepared and kept at the main distribution point. This forms part of the as-built documentation for the installation.
Regulation 710.53 — Isolation and switching: A means of switching off the electrical supply to each Group 2 location in an emergency must be provided outside the room, clearly labelled, and accessible to authorised persons only. This must not interrupt the supply to essential circuits fed from the Category 1 essential supply.

04 · Healthcare Electrical Guide

Isolated Power Supplies (IT Systems) in Hospitals

The IT system is the defining electrical feature of Group 2 medical locations. Understanding how IT systems work, and how to install and test them correctly, is essential for electricians working in operating theatres and critical care environments.

Medical isolation transformer: A medical-grade isolation transformer (compliant with BS EN 61558-2-15) separates the Group 2 circuit from the earthed supply, creating an unearthed (isolated) secondary. The transformer is typically rated 0.5 kVA to 10 kVA and is specifically designed for medical use with reinforced insulation and a secondary leakage current not exceeding 0.5mA.
Insulation Monitoring Device (IMD): The IMD continuously measures the insulation resistance between each conductor of the IT system and earth. When the combined insulation resistance falls below the alarm threshold (typically 50 kΩ at 25V DC test voltage), a visual and audible alarm is activated at the local alarm panel in the medical location. The alarm does not interrupt supply — it signals the need for maintenance action.
Load line monitor (LIM): A load line monitor (also called a line isolation monitor in some standards) indicates the total hazard current that would flow in the event of a fault. In US-influenced specifications this device is prominent; in UK practice the IMD described in BS 7671 Section 710 serves the same function.
Testing: IT systems must be tested on commissioning and at regular intervals. Testing includes: verification of IMD alarm function, measurement of transformer secondary leakage current, insulation resistance measurement of all circuits, and verification of equipotential bonding continuity throughout the patient environment.

05 · Healthcare Electrical Guide

Essential Services and UPS Systems in Hospitals

The essential services electrical system ensures that power is maintained to life-critical equipment and safety systems when the normal mains supply fails. HTM 06-01 defines three categories of essential supply with different changeover time requirements.

Category 1 — No-break supply (0 to 0.5 seconds): Supplied by a UPS system. Covers life support equipment, cardiac monitors, critical alarm systems, and operating theatre lighting. The UPS must bridge the gap between mains failure and generator start without any interruption to supply.
Category 2 — Short-break supply (up to 15 seconds): Supplied via Automatic Transfer Switches (ATS) from the generator. Covers emergency lighting, general operating theatre power, endoscopy, and high-dependency ward circuits. The generator must start, reach stable voltage and frequency, and the ATS must transfer within 15 seconds of mains failure.
Category 3 — Delayed supply (up to 60 seconds): General essential services including ward lighting, general power outlets outside patient areas, catering, and administrative systems. Transferred to the generator after the Category 1 and 2 loads have been established.
Essential supply testing: HTM 06-01 requires regular full-load tests of the essential supply system, including simulated mains failure, generator start, and ATS changeover. Test results must be recorded and retained. The Electricity at Work Regulations 1989 require maintenance records to be kept.

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06 · Healthcare Electrical Guide

Health Technical Memorandum HTM 06-01

HTM 06-01 (Health Technical Memorandum 06-01: Electrical Services Supply and Distribution) is the NHS England guidance document for all aspects of healthcare electrical services. While not itself a statutory instrument, it is considered the authoritative technical guidance for NHS facilities and compliance with it is expected by NHS Estates teams and the CQC.

Authorising Engineer (Electrical): HTM 06-01 requires NHS trusts to appoint an Authorising Engineer (Electrical) — an independent, suitably qualified person who advises management on electrical safety policy and procedures, and who authorises the Appointed Persons responsible for the electrical installation.
Permit to Work system: All electrical maintenance and modification work in hospitals must be carried out under a formal Permit to Work system. The PTW defines the work scope, isolation points, testing requirements, and safe working conditions. No live electrical work should be undertaken without specific authorisation.
Periodic inspection: HTM 06-01 specifies inspection frequencies for all categories of electrical installation in healthcare premises. Group 2 medical locations require annual testing of the IT system and equipotential bonding. The main electrical installation should be inspected at intervals not exceeding those specified in BS 7671 for the installation type.
Asset register: HTM 06-01 requires a comprehensive asset register for all electrical plant, including switchgear, transformers, generators, UPS systems, and distribution boards. The register must record specifications, test dates, maintenance history, and condition ratings.

07 · Healthcare Electrical Guide

Medical Grade RCDs and Circuit Protection

Protective device selection in medical locations requires careful consideration of the conflicting requirements for patient safety (requiring disconnection of faulty circuits) and clinical safety (requiring continuity of supply to life-critical equipment).

Group 1 socket outlets: In Group 1 medical locations, all socket outlets within the patient environment must be protected by a 30mA RCD in accordance with Regulation 710.411.3.2.5 of BS 7671. Type A RCDs are suitable for most applications; Type B RCDs are required where equipment with DC residual current components (such as some MRI-compatible equipment) is connected.
Group 2 — no standard RCDs: In Group 2 locations, standard 30mA RCDs are not used on circuits within the patient environment because a nuisance trip during surgery could be fatal. Protection is provided by the IT system and IMD as described above, combined with supplementary equipotential bonding.
Overcurrent protection: Circuit breakers in medical locations must be selected to achieve correct discrimination between upstream and downstream devices. A fault on a single circuit must not cause an upstream device to operate and disconnect a larger section of the installation. Discrimination should be verified by calculation during the design stage.

08 · Healthcare Electrical Guide

Earthing and Equipotential Bonding in the Patient Environment

Earthing and bonding in medical locations is more extensive than in standard commercial premises. The patient environment contains multiple conductive surfaces and electrical devices, all of which must be maintained at the same electrical potential to prevent dangerous currents flowing through the patient.

Supplementary bonding: All simultaneously accessible conductive parts within the patient environment (1.5m horizontal, 2.5m vertical from the patient) must be connected by supplementary equipotential bonding conductors to a local equipotential bonding bar (patient zone bonding bar). This includes bed frames, medical equipment frames, metallic pipework, HVAC components, and structural steelwork.
Bonding conductor sizing: Supplementary bonding conductors must be sized in accordance with Regulation 544.2 of BS 7671, with a minimum cross-sectional area of 2.5 mm² if mechanically protected or 4 mm² if not mechanically protected.
Bonding verification: The resistance of each supplementary bonding connection must be measured on commissioning and periodically thereafter. BS 7671 Section 710 requires a maximum resistance of 0.2 ohm between any two simultaneously accessible conductive parts within the patient environment.

09 · Healthcare Electrical Guide

For Electricians: Working in Healthcare Environments

Hospital and healthcare electrical work offers excellent career development opportunities for UK electricians. The specialism commands higher rates than standard commercial work, and NHS frameworks provide steady pipeline of maintenance, refurbishment, and new build projects.

Infection Control and Site Rules

Working in clinical areas requires compliance with hospital infection control policies. Electricians may need to wear PPE, use designated tools, and follow strict procedures for working in sterile environments. Familiarise yourself with site-specific requirements before commencing work.

On-Site Certification

All electrical work in healthcare premises must be certified. Use the Elec-Mate certification app to complete Electrical Installation Certificates and test schedules on site, with immediate PDF delivery to the NHS Estates team.

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Frequently Asked Questions — Hospital Electrical Installation

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Hospital Electrical Installation UK: Healthcare Systems Guide

Key Takeaways

Hospital Electrical Installation in the UK

Get the BS 7671 A4:2026 Cheat Sheet — free

Class 1 and Class 2 Medical Locations

IEC 60364-7-710 and BS 7671 Section 710

Isolated Power Supplies (IT Systems) in Hospitals

Essential Services and UPS Systems in Hospitals

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Health Technical Memorandum HTM 06-01

Medical Grade RCDs and Circuit Protection

Earthing and Equipotential Bonding in the Patient Environment

For Electricians: Working in Healthcare Environments

Infection Control and Site Rules

On-Site Certification

Manage healthcare electrical projects with Elec-Mate

Frequently Asked Questions — Hospital Electrical Installation

What is IEC 60364-7-710 and how does it apply to UK hospital electrical installations?

What is a Group 2 medical location and what are the electrical requirements?

What is an IT system (isolated power supply) in a hospital context?

What does HTM 06-01 require for hospital essential services?

What RCD requirements apply to hospital electrical installations?

Who is qualified to design and install hospital electrical systems in the UK?

What earthing arrangements are required in the patient environment?

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