National Highway Sector Scheme 8 (NHSS 8, or simply “Scheme 8”)

In the domain of highway works and infrastructure, electrical systems play a vital role: street lighting, traffic signals, variable message signs (VMS), communications equipment, sensors, CCTV, and more. Ensuring those systems are installed, maintained, and managed properly is critical not just for functionality but for safety, reliability, and compliance with standards.

To bring rigor, consistency, and quality assurance into this domain, the UK highways sector uses National Highway Sector Scheme 8 (NHSS 8, or simply “Scheme 8”), which is the document that defines the standard requirements for overseeing, installing, or maintaining highway electrical equipment and associated works. It acts as a sector-specific overlay to ISO 9001, specifying additional obligations relevant to the highway electrical environment.

In this blog I’ll walk through:

1. The background and rationale for Scheme 8

2. The scope and key elements of the document

3. How the structure of Scheme 8 maps onto quality management and technical requirements

4. The processes for certification, auditing, and compliance

5. Practical challenges in implementation

6. Best practices for organisations working under Scheme 8

7. Recent updates, trends, and future directions

8. A summary and conclusions

1. Background and Rationale

1.1 National Highway Sector Schemes (NHSS)

Scheme 8 is part of a family of National Highway Sector Schemes, each of which applies to a particular class of highway works (e.g. road marking, barriers, traffic signs). These sector schemes are overlaid on ISO 9001 (Quality Management Systems) to give additional, sector-specific requirements.

The purpose of the sector schemes is to ensure consistent quality, safety, compliance, and best practices across highway works, especially when multiple contractors and subcontractors are involved. The highways authority (e.g. Highways England or successors) often mandates that contracting entities are compliant with relevant sector schemes, including Scheme 8 for electrical works.

1.2 Why a specific Scheme for electrical works?

Electrical and electronic systems in the highway environment come with particular challenges:

• They must deal with power, earthing, fault protection, signaling, and more under roadside, harsh environmental, and traffic conditions.

• Some installations (e.g. lighting columns, signal heads, communications masts) are in proximity to live traffic or over/near carriageways.

• Access, maintenance, faults, civil works (ducting, trenching, reinstatement) and interface with other highway works make them complex.

• The safety implications of electrical failure are high (risk of electric shock, fire, system failure).

Because generic ISO 9001 does not cover the domain-specific risks and controls, Scheme 8 was developed to incorporate the necessary technical, safety, and procedural requirements tailored to the highway electrical sector.2. Scope and Definitions of Scheme 8

2.1 Scope

Scheme 8 covers the “overseeing and/or installation and/or maintenance of highway electrical equipment and supporting works.”

Appendix K of the Scheme provides more detail: the scope includes but is not limited to:

• Traffic control equipment and associated apparatus

• Variable message signs (VMS)

• Communications equipment and associated apparatus

• Environmental and monitoring equipment

• Cameras and associated apparatus

• Ramp metering equipment

• Highway lighting columns, posts, other street furniture

• Cables in trenches or ducts (and the excavation and reinstatement works)

• Inductive loops, power cable slots, etc.

• Highway lighting and illuminated traffic signs

• Non‑illuminated traffic signs and associated apparatus

• Electrically powered bus shelters or advertising structures

• Equipment in tunnels or tunnel bores and access areas

• Electric vehicle charging points or on-street highway electrical equipment

Hence, the scope is broad and spans typical installations, ongoing maintenance, upgrades, and oversight functions.

Note that pure civil works (excavation, reinstatement) when unrelated to electrical systems are excluded; the “supporting works” always relate to the electrical equipment.

2.2 Definitions – “Overseeing,” “Maintenance,” “Installation”

• Installation: the act of placing, wiring, connecting, and commissioning the electrical equipment and structural supports, cables, etc.

• Maintenance: periodic inspection, preventive or corrective maintenance, repair or replacement of faulty parts or systems.

• Overseeing: functions of investigation, direction, or checking of works on behalf of the client (not just a contractor managing their own works). Overseeing covers independent monitoring or supervision roles (but not necessarily routine contractor oversight).

Also, the term “highway electrical equipment and supporting works” is defined broadly to include both electrical and non-electrical components (e.g. mounting posts) insofar as they relate to the systems under the Scheme.

2.3 Normative References

Scheme 8 is intended to work in conjunction with:

• ISO 9001 (Quality Management System standard)

• Contract specifications (e.g. Specification for Highway Works)

• National or European standards for electrical installations, construction, and safety

It also references compliance with regulations such as the Construction Products Regulation, health & safety regulations, and CDM (Construction Design and Management) as appropriate.

3. Structure and Key Provisions of Scheme 8

Scheme 8 is structured to overlay additional sector-specific requirements on top of ISO 9001, particularly in these areas:

• Interpretation and adaptation of QMS clauses

• Quality plans and project-specific planning

• Training, competence, and safety

• Technical controls and inspection regimes

• Auditing, nonconformities, corrective actions

• Scope and certificates

• Appendices (A, B, C, K, etc.)

Below is an outline of how Scheme 8 addresses these.

3.1 Quality Management System Requirements (Sections 4–8)

The document begins by aligning with ISO 9001’s structure (clauses 4–8), but adds sector-specific obligations. For example:

• The organisation must have documented processes, but also show how they are adapted to highway electrical works (e.g. down to cable installation, looping, signal heads, etc.).

• The certification body must assess that the organisation’s processes incorporate safety, traffic management, competence, and highway constraints.

• The organisation must maintain up-to-date references to the latest Scheme version.

3.2 Quality Plans (Appendix A)

Project-specific quality plans are central in detailing how the generic QMS will be applied to a particular highway electrical contract. The requirements include:

• Identification of responsibility, interfaces, and authority

• Risk assessments and safety measures specific to the site

• Inspection and test schedules for components, cabling, joints, commissioning

• Acceptance criteria for each stage

• Records and traceability requirements

The quality plan ensures that the high-level QMS is concretely implemented in each contract or site.

3.3 Training, Competence, Health & Safety (Appendix C)

Scheme 8 emphasises that all personnel must be competent and appropriately trained, especially for highway electrical works which involve both electrical risk and traffic risk. Key points:

• The organisation must assess and maintain records of employee competence

• There must be training programs, refresher courses, and assessment

• Authorised Persons (APs), Authorising Officers (AOs), and Qualified Supervisors (QS) play critical roles

• Health & safety training must address CDM, working near live traffic, excavation hazards, electrical hazards

In the highway electrical sector, one of the practical mechanisms is through HERS (Highway Electrical Registration Scheme), administered by the Highway Electrical Association (HEA). Under HERS, individuals are assessed and certificated (ECS/HERS card) to demonstrate compliance with NHSS 8 requirements.

The HEA runs courses for AOs and QSs as part of this scheme.

3.4 Technical and Operational Controls

These are imbedded throughout with references to detailed inspections, testing, and acceptance criteria. Some of the technical controls include:

• Inspection of structural supports, mechanical and electrical components

• Verification of cable continuity, insulation resistance, earthing

• Site environmental resilience (weatherproofing, ingress protection)

• Protection against overload, fault conditions, surge protection

• Inspection of joints, terminations, and connectors

• Commissioning tests and acceptance tests

• Periodic maintenance inspections  preventive and reactive

• Fault reporting and corrective actions

 must plan appropriate inspection frequencies, maintain records, and respond to nonconformities.

3.5 Audits, Nonconformities, Corrective Actions

Scheme 8 requires that the organisation:

• Conduct internal audits specific to the highway electrical scope

• Provide processes for nonconformity management and corrective / preventive actions

• Maintain records of corrective actions, lessons learned, trend analysis

• Support external audits by certification bodies who evaluate not only the QMS but the sector-specific obligations

3.6 Certification, Certificates, and Scope (Appendix K)

Appendix K is especially important. It provides:

• The detailed scope of works that may be included in the certificate (i.e. which categories of electrical highway works the organization is authorized for)

• The validity period and renewal requirements

• The format and content required on certificates

• Clarifications of the boundaries: e.g. which items can be included, which are excluded, etc.

An organisation’s certificate will state which elements of the scheme scope they cover, e.g. lighting, VMS, communications, etc.

3.7 Implementation and Transition

When a new version of Scheme 8 is published, organisations must transition to the new version by their next audit or surveillance visit.

The certification body must ensure assessors are knowledgeable in the new requirements. Certification, Registration & Compliance

4.1 Certification Bodies & Assessors

To be certified under Scheme 8, an organization must go through an accredited Certification Body (CB) which is approved to assess compliance with ISO 9001 plus the additional sector scheme clauses. The assessors must have:

• IRCA (or equivalent) lead auditor qualification or equivalent

• Sufficient technical knowledge of highway electrical works

• Adequate health & safety competence, including CDM / traffic works context

The CB conducts:

• Initial assessment

• Surveillance audits (typically annually)

• Reassessment every three years

• Spot checks across the full scope

They verify that the organisation adheres to both generic and sector-specific requirements.

4.2 Highway Electrical Registration Scheme (HERS)

Beyond organisational certification, HERS is the personnel/competence registration scheme for individuals working under NHSS 8. It ensures that employees are assessed as Authorised Persons, Qualified Supervisors, etc. and issued a registration card (ECS / HERS card) validating that they meet the competence requirements.

Employers must ensure their staff hold the appropriate registrations. HERS also conducts technical audits of registered organizations to maintain compliance.

4.3 Contractual Mandates

Highways authorities frequently require, in their contracts, that all firms doing highway electrical works must hold Scheme 8 certification and that employees be HERS-registered. This makes compliance a practical necessity in public-sector highway work.

4.4 Maintaining Compliance

To maintain compliance, organizations must:

• Keep their QMS aligned with scheme updates

• Renew certificates and undergo audits

• Ensure personnel maintain competence and registration

• Demonstrate implementation of quality plans and technical compliance in contracts

• Respond promptly to nonconformities

• Monitor performance and continuously improve

5. Challenges and Practical Considerations

Implementing Scheme 8 in real-world operations is not trivial. Some of the common challenges include:

5.1 Integration with Existing QMS

Many contractors already have ISO 9001 QMS; overlaying Scheme 8 requires tailoring processes for the highway electrical context. Ensuring the documentation, procedures, and records properly reflect the added controls (electrical testing, traffic safety, inspection) can be time-consuming.

5.2 Technical Complexity and Variety

The diversity of electrical works (lighting, signals, communications, tunnels, EV chargers, etc.) means the organization needs expertise across many subdomains. Ensuring competence across all these is demanding.

5.3 Coordination with Civil Works

Electrical works often have dependencies with excavation, ducting, reinstatement, structural works, etc. Coordination with civil contractors is essential. Ensuring that quality plans account for interface points is challenging.

5.4 Traffic Management and Safety

Working adjacent to live traffic presents additional hazards. Organisations must ensure that staff are trained in traffic management, signage, work zone safety, and risk mitigation. Mistakes can have serious safety consequences and liability.

5.5 Version Updates and Transition

When Scheme 8 is revised, organisations must transition by the next audit. If updates are substantial, this may require reworking many procedures, retraining staff, and preparing for new audit criteria.

5.6 Audit Scope and Depth

Certification bodies must ensure that assessments reach down to the “shop floor” and field-level activities (e.g. cable splicing, jointing, field testing). If audits stay too high-level, gaps may persist.

5.7 Cost and Resource Commitment

Achieving and maintaining certification incurs cost: audit fees, internal resource time, staff training, process improvement. Smaller firms may struggle with overhead.

5.8 Competence and Personnel Turnover

Ensuring that all staff remain competent and registered (through HERS) is a constant administrative burden, especially when people leave or join.

6. Best Practices for Organisations under Scheme 8

To succeed under Scheme 8, here are some recommended practices:

6.1 Gap Analysis & Planning

When starting, conduct a detailed gap analysis comparing current systems to Scheme 8 requirements. Develop a roadmap and resource plan for closing gaps.

6.2 Strong Quality Plans

Use robust, detailed project quality plans that translate generic procedures into site-specific controls, inspection schedules, interface management, risk mitigation, and acceptance criteria.

6.3 Embed Processes into Daily Work

Don’t treat Scheme 8 compliance as an add-on; integrate technical checks, test records, safety checks, and quality controls into everyday operations and site workflows.

6.4 Training & Competence Management

• Conduct regular training and refresher courses

• Use assessments and audits of personnel competence

• Keep records up to date

• Ensure succession and redundancy planning

6.5 Close Interface Management

When working alongside civil, structural, or highway contractors, coordinate interfaces, communication, handovers, and inspection checkpoints clearly in contracts and quality plans.

6.6 Proactive Audits and Internal Checks

Perform internal audits (site walk-throughs, toolbox talks, witness inspection) targeted at scheme requirements. Use findings as improvement opportunities.

6.7 Liaise with Certification Body

Maintain good communication with the CB to clarify expectations, audit approach, and assure assessors understand the specific highway electrical environment.

6.8 Continuous Improvement

Use metrics (defect rates, nonconformity trends, audit findings) and lessons learned to refine procedures, training, and quality controls over time.

6.9 Change Control & Version Management

When scheme revisions occur, plan early for procedural updates, training, and documentation changes to avoid noncompliance at the time of audit.

6.10 Visibility & Culture

Promote organisational awareness of Scheme 8, embed accountability, ensure that site supervisors and staff understand why compliance matters (safety, reputation, contract eligibility).

7. Recent Updates, Trends, and Future Directions

7.1 Version Updates

The formal update to Scheme 8’s “Particular Requirements for the Application of ISO 9001:2015” was published in November 2018 (Edition 2) to supersede the older ISO 9001:2008 version.

This update introduced amendments in several appendices and clauses (e.g. Appendix K expansions, training and competence, feedback mechanisms) to reflect evolving technologies and practices.

7.2 Inclusion of New Technologies

As highway electrification and smart infrastructure expand, Scheme 8’s scope is evolving to include:

• Tunnel electrical systems

• Electric vehicle (EV) charging infrastructure on-street

• Communications and sensor networks

• More advanced environmental monitoring equipment

• Enhanced resilience (e.g. surge protection, remote diagnostics)

These developments demand greater integration between electrical, electronic, and civil systems, putting pressure on scheme requirements and competence. Scheme 8 already anticipates some of these in Appendix K. 7

7.3 Emphasis on Digital & Remote Monitoring

With smarter highways, remote monitoring, diagnostic systems, and digital asset management are becoming more common. Scheme 8 may in the future emphasize requirements around cybersecurity, remote failure detection, predictive maintenance, and data logging.

7.4 Integration with Sustainability and Resilience

Increasingly, highway authorities are requiring energy efficiency (LED lighting, dimming control), resilience to climate change, low-carbon systems, and circular economy practices. Scheme 8 may in future incorporate references to sustainability standards.

7.5 Greater Emphasis on Safety and Risk

As systems get more complex and interdependent, the importance of risk assessment, hazard analysis, and safety in design and maintenance becomes even more pronounced.

8.

Scheme 8 is the essential sector-specific standard for any organisation involved in the overseeing, installation, or maintenance of highway electrical systems in the UK. By combining ISO 9001’s quality management framework with domain-specific obligations (technical controls, testing, safety, competence), it provides a robust governance for highway electrical works.

Key takeaways:

• Scheme 8 clarifies scope, roles, responsibilities, and technical requirements for highway electrical infrastructure.

• Certification via a recognised body and complementary personnel registration via HERS are required for compliance.

• Practical implementation demands detailed quality planning, strong interface coordination, competent personnel, and continuous auditing and improvement.

• Challenges include integration with existing systems, keeping up with updates, and balancing overhead cost with operational needs.

• The future likely sees stronger emphasis on smart technologies, environmental concerns, resilience, and digital monitoring.