BS 5266-1:2025 Explained: Essential Guide for UK Electricians
- Docs Store
- Nov 17
- 7 min read
What Electricians Need To Know About The New Emergency Lighting Standard
Emergency lighting plays a vital role in keeping people safe during any loss of mains power. With the release of BS 5266-1:2025, the UK now has a major update to the code of practice that governs the design, installation and maintenance of these life safety systems.
This new edition replaces BS 5266-1:2016 and updates references to the latest European standards BS EN 50172:2024 and BS EN 1838:2024, incorporating practical lessons learned across the building industry. For electricians, designers and installers, understanding what has changed is essential for safe and compliant work.
In this guide, you'll learn:
Key changes in BS 5266-1:2025
New wiring and circuit requirements
Updated testing and verification rules
Practical compliance steps for electricians
Why BS 5266-1:2025 Matters for Emergency Lighting
The 2025 edition is a full revision of the UK code of practice for emergency lighting. It gives clearer guidance for modern buildings, where evacuation is not always the only emergency strategy. It strengthens the rules around performance, wiring and verification so that emergency lighting systems remain reliable throughout their life.
For electricians, this standard is the foundation for safe design and compliant installation. It supports duties under the Regulatory Reform (Fire Safety) Order 2005 and gives building owners stronger assurance that their lighting systems will work when needed.
Key Changes Electricians Must Know
1. Expanded Scope
The 2025 edition now formally covers three categories of emergency lighting:
Emergency escape lighting – for safe evacuation
Emergency local area lighting – for situations where people may remain in the building during a supply failure
Standby lighting – where normal operations must continue
2. Emergency Lighting Terminology Updates
The standard now formally defines "emergency local area lighting" (Clause 3.9) for situations where occupants are allowed to remain temporarily in premises during a mains supply failure, provided activities are risk-assessed.
Important: The standard explicitly states that borrowed light cannot be relied upon to meet emergency lighting requirements (Clause 3.3 and Scope).
3. New Wiring Requirements for Emergency Lighting Systems
BS 5266-1:2025 introduces clearer rules that improve system resilience:
Maximum 20 luminaires affected by a single fault on centrally supplied final circuits (Clause 8.2.1.g)
High-risk task areas must have dual circuit supply from at least two separate circuits (Clause 8.2.1.f)
Cable routing through low fire-risk areas wherever practicable (Clause 8.2.1.b)
Fire-resistant cables required for central power supply systems:
"Standard 60" – 60-minute fire resistance
"Enhanced 120" – 120-minute fire resistance (Clause 8.2.2)
Self-contained luminaires follow normal lighting circuit standards – no fire-protected cables required (Clause 8.1)
4. Emergency Lighting System Integrity Rules
To prevent total darkness if a single luminaire fails:
Minimum two luminaires (or emergency exit signs with downward light) must illuminate each room and escape route (Clause 6.3)
Verification performed with all doors shut
Ensures backup illumination always available
5. Five-Year Photometric Verification
One of the biggest practical changes: photometric verification required every 5 years (Clauses 11.2 and 12).
Every five years, actual light output and distribution must be:
Measured with calibrated equipment
Recorded in the logbook
Confirmed to meet design requirements
This goes beyond functional testing – it's a proper illuminance survey.
6. Emergency Lighting Performance Standards Updated
BS 5266-1:2025 references the latest EN lighting performance standards. Important values include:
Escape routes: minimum 1 lux across the full route width (excluding borders)
Open areas: minimum 0.5 lux at floor level
High-risk task areas: minimum 15 lux or 10% of normal lighting, whichever is higher, with full illuminance achieved within 0.5 seconds (Clause 5.2.7)
Points of emphasis (fire alarm call points, exit doors, firefighting equipment, first aid posts): minimum 5 lux vertical illuminance
These requirements ensure buildings receive consistent and predictable illumination during an emergency.
7. Emergency Lighting Duration Requirements Clarified
The standard provides clear guidance on system duration (Clause 6.7.3):
3-hour minimum duration required for:
Sleeping accommodation (hotels, care homes, hospitals)
Entertainment venues (theatres, cinemas)
Premises with phased evacuation
Buildings reoccupied before batteries fully recharge
1-hour minimum duration acceptable only when:
Premises evacuate immediately on supply failure
No reoccupation until full battery capacity is restored
8. Emergency Exit Sign Requirements Updated
Escape route signs must use graphical symbols E001 and E002 from BS EN ISO 7010:2020+A8 with appropriate directional arrows (Clause 5.2.9.1).
9. Emergency Lighting Battery Life Standards
Minimum declared battery life expectancy (Clause 7.2):
Self-contained luminaires: 4 years minimum
Central safety power supply (high power): 10 years at 20°C
Central low power supply systems: 5 years at 20°C
10. Competent Person Definition and Record Keeping
Competent person (Clause 3.5) applies to individuals and organisations – defined as "suitably trained and qualified by knowledge and practical experience" with necessary instructions.
Detailed record keeping now mandatory:
Commissioning and verification (Clause 11)
Monthly functional tests (Clause 12)
Annual full duration tests and visual inspections (Clause 12)
Five-yearly photometric verification (Clause 12)
All maintenance and repair activities (Clause 13)
Emergency lighting logbook required (Annex J) containing:
Contractual and legal details
Risk analysis
Equipment specifications
Design calculations and drawings
Commissioning data
Maintenance schedules
Agreed variations
11. Automatic Test Systems Emphasised
BS 5266-1:2025 places increased emphasis on automatic test systems (Clause 12, Note 1), particularly for premises where occupants remain during supply failures.
Emergency Lighting Standards Quick Reference
Standard | What It Covers | When You Use It |
BS 5266-1:2025 | Code of practice for emergency lighting design, installation, commissioning and maintenance | Use for all planning, design and installation work |
BS EN 50172:2024 | Testing, inspection, maintenance and procedure | Use for ongoing building management and system care |
BS EN 1838:2024 | Lighting performance requirements, including illuminance and response times | Use for photometric design and verification |
BS EN IEC 60598-2-22 2022 | Requirements for emergency luminaires | Use when selecting luminaires |
BS EN 50171 2021 | Central battery and emergency power supply systems | Use for central supply design |
BS 7671:2018 + A3 2024 | Wiring regulations | Use for all electrical installation work |
BS EN ISO 7010:2020+A8:2024 | Safety signs and exit signage | Use when specifying and installing signage |
What BS 5266-1:2025 Means For Electricians
The changes in BS 5266-1:2025 are designed to improve safety and resilience. For day-to-day practice this means:
✓ Design considerations: Full width of escape routes, not just centre-line spacing
✓ System selection: Assess need for local area and standby lighting
✓ Wiring standards: Robust cable routes with appropriate fire protection
✓ Circuit separation: Limit impact of any single fault
✓ System integrity: Multiple luminaires covering each area
✓ Testing regime: Monthly, annual, and five-yearly verification
✓ Documentation: Comprehensive logbook and audit trail
✓ Duration planning: Based on evacuation strategy
✓ Battery specifications: Correct life expectancy for system type
These expectations raise the standard of installation work but also improve confidence in the system when it is needed most.
How to Comply with BS 5266-1:2025: Practical Steps
Update your templates and design tools
Ensure drawings reflect 2025 illuminance requirements
Update calculation spreadsheets
Revise specification templates
Include new performance values
2. Review Emergency Lighting Wiring Strategies.
Implement circuit separation requirements
Specify fire-resistant cables for central systems
Route circuits through low fire-risk areas
Limit 20 luminaires per circuit
3. Carry Out Thorough Commissioning
Use calibrated illuminance meters
Verify performance at key locations
Complete comprehensive handover documentation
Provide detailed logbook
4. Plan Emergency Lighting Testing Schedule
Create maintenance schedule including:
Monthly: Functional tests
Annual: Full duration tests and visual inspections
Every 5 years: Photometric verification
Consider automatic test systems for reliability.
5. Provide Training
Train responsible persons on new requirements
Explain testing procedures
Demonstrate record-keeping systems
Cover maintenance responsibilities
6. Maintain Detailed Records
Keep logbook updated with:
All test results
Repair actions
Battery replacements
System modifications
Agreed variations from the standard
Emergency Lighting Compliance Checklist
Use this checklist to ensure BS 5266-1:2025 compliance:
Design Phase:
✓ Risk assessment completed
✓ Escape routes identified
✓ Open areas assessed
✓ High-risk task areas identified
✓ Illuminance calculations performed
✓ System duration determined (1h or 3h)
✓ Equipment specifications documented
Installation Phase:
✓ Fire-resistant cables specified (central systems)
✓Circuit separation implemented
✓ Maximum 20 luminaires per circuit
✓ System integrity verified (minimum 2 luminaires)
✓Correct signs installed (E001/E002)
✓Wiring through low fire-risk routes
Commissioning Phase:
✓ Illuminance verification completed
✓Duration testing performed
✓Automatic test systems configured
✓Logbook created and populated
✓Handover documentation provided
✓Responsible person trained
Maintenance Phase:
✓ Monthly functional tests scheduled
✓ Annual duration tests planned
✓ Five-yearly photometric verification scheduled
✓ Record-keeping system established
✓ Competent person appointed
Common BS 5266-1:2025 Questions Answered
Q: Do all emergency lighting systems need 3-hour duration?
A: No. 1-hour duration acceptable if premises evacuate immediately and aren't reoccupied until batteries recharged. 3 hours required for sleeping accommodation, entertainment venues, or where reoccupation happens quickly.
Q: Can I use borrowed light for emergency lighting?
A: No. BS 5266-1:2025 explicitly states borrowed light cannot meet emergency lighting requirements.
Q: Do self-contained luminaires need fire-resistant cables?
A: No. Self-contained luminaires follow normal lighting circuit standards under BS 7671. Only central supply systems require fire-resistant cables.
Q: How often must photometric verification occur?
A: Every 5 years maximum. This measures actual light output and confirms design requirements still met.
Q: What's the maximum luminaires on one circuit?
A: 20 luminaires maximum on centrally supplied final circuits to limit impact of single faults.
Q: Are automatic test systems mandatory?
A: Not mandatory, but strongly recommended, especially where occupants remain during supply failures.
Resources for Emergency Lighting Professionals
Essential standards:
Further guidance:
CIBSE/SLL LG12 Emergency Lighting
HSE Lighting at Work (HSG38)
Final Thoughts: BS 5266-1:2025 Implementation
BS 5266-1:2025 brings the UK code of practice in line with modern building needs and the latest European standards. It introduces clearer performance targets and stronger requirements for resilience, verification and documentation.
For electricians, this means:
More detailed design work
Enhanced circuit protection
Greater emphasis on competence
Comprehensive record-keeping
Regular photometric verification
The result is improved safety and more reliable emergency lighting throughout operational life.
Whether designing new installations or maintaining existing systems, understanding these changes helps deliver compliant, reliable emergency lighting that protects building occupants when they need it most.
About Emergency Lighting Standards
Emergency lighting standards protect lives by ensuring adequate illumination during power failures. BS 5266-1:2025 represents the latest UK guidance for electricians, installers, and building managers responsible for emergency lighting system design, installation, and maintenance.
Related Articles:
Understanding BS EN 50172:2024 Requirements
Emergency Lighting Testing Procedures Explained
Fire-Resistant Cable Selection Guide
BS 7671 Emergency Lighting Circuits
Tags: BS 5266-1:2025, emergency lighting, electrician guide, UK building regulations, BS EN 50172, emergency lighting testing, fire safety, electrical standards, BS 7671, emergency lighting installation