title: "NPS EN-5 - Electricity Networks Infrastructure" type: wiki source: nps-en-5 date: 2024-01-17 updated: 2026-04-12 tags: [nps, transmission, overhead-lines, substations, nsip, holford-rules, undergrounding]

NPS EN-5 - Electricity Networks Infrastructure

Canonical source: ~/knowledge/sources/desnz/nps-en-5.md

Primary URL: gov.uk - NPS EN-5

What EN-5 Covers

NPS EN-5 is the decision-making framework for nationally significant electricity networks infrastructure in England and Wales. It applies alongside the overarching EN-1 for all Development Consent Order (DCO) applications in scope.

EN-5 covers above-ground electricity lines (overhead lines) at 132kV nominal voltage or above, where the line is greater than 2km in length, plus associated substations, converter stations, and underground cable sections where these form part of the same project.

Below-threshold lines (under 132kV, or under 2km, or replacement lines) require Electricity Act 1989 s.37 consent, not a DCO. EN-5 does not govern s.37 applications.

NSIP Threshold

Planning Act 2008 s.16 sets the threshold. An above-ground electricity line is a Nationally Significant Infrastructure Project if:

• Nominal voltage 132kV or above
• Length greater than 2km
• Not a replacement line (s.16(3)(ab) exemption)
• Not otherwise exempted under s.16(3)(b)/(c), (3A), or (3B)

132kV lines associated with a devolved Welsh generating station are excluded. The Secretary of State can direct below-threshold projects into the NSIP regime under Planning Act 2008 s.35.

Designation History

• 2011: Original EN-5 designated as part of the first suite of energy NPSs.
• 2024: Revised EN-5 designated 17 January 2024. Key changes: CNP status conferred on all in-scope infrastructure, reversed undergrounding presumption in National Parks and National Landscapes formalised, CSNP/HND network planning references added, offshore-onshore transmission section expanded, SF6 minimisation introduced.
• 2026: 2025 revision designated 6 January 2026. Currently in force. Updated references to Electricity Transmission Design Principles (ETDP) and revised CSNP provisions.

The 2024 version governs applications accepted before 6 January 2026.

Need Case in the CP2030 Era

All electricity network infrastructure in scope of EN-5 is designated Critical National Priority (CNP) infrastructure. This is the highest planning priority tier under EN-1.

The policy basis is Clean Power 2030: a large volume of transmission reinforcement is required to connect contracted offshore wind and carry generation from coastal and rural landing points to demand centres. The CSNP (Centralised Strategic Network Plan), led by NESO, identifies and endorses the specific investment programme. EN-5 provides the consenting framework.

CNP status means: residual non-HRA impacts are unlikely in all but the most exceptional circumstances to outweigh the urgent need for this infrastructure. The planning balance is strongly weighted toward approval for in-scope applications.

Holford Rules and Overhead Line Routing

The Holford Rules are 1959-vintage routing principles for overhead lines, carrying material weight under EN-5. In summary:

• Avoid the highest-amenity areas by planning the route first, even at the cost of extra mileage
• Deviate to avoid smaller high-amenity areas, but minimise angle towers
• Choose the most direct line consistent with the above
• Use tree and hill backgrounds over sky backgrounds; cross ridges between tree belts or obliquely
• Prefer valleys with tree cover over flat open terrain
• In flat, sparse terrain, avoid wirescape by keeping high-voltage lines clear of distribution poles and other masts
• Approach urban areas through industrial zones; assess undergrounding costs carefully where residential or recreational land intervenes

The Holford Rules are routing and design discipline within the overhead line presumption. They do not reverse it outside nationally designated areas.

Undergrounding: Presumption and Exceptions

Default: Overhead lines are the strong starting presumption for electricity network infrastructure generally. Lower capital cost, lower lifetime maintenance cost, and easier upgrading support this presumption.

In National Parks, The Broads, and National Landscapes (formerly AONBs): The presumption is reversed. Where harm to scenery, visual amenity, and natural beauty cannot be avoided by re-routing, the strong starting presumption is that the applicant should underground the relevant section.

Undergrounding is not required in nationally designated areas where: - It is infeasible in engineering terms; or - The harm that undergrounding causes is not outweighed by its benefits to scenery, visual amenity, and natural beauty

Cost and feasibility test: The Secretary of State must weigh the cost and harm of undergrounding (including significantly higher lifetime cost of repair and later uprating) against the adverse implications of the overhead option, the cost of re-routing, and the cost of using proximate existing underground or subsea infrastructure.

The explicit inclusion of lifetime cost as an undergrounding burden means that even in nationally designated areas, very long high-voltage underground sections face a high bar. The presumption is reversed but the exception is not narrow.

Key Balance: Scenery vs. Network Need

The central tension in EN-5 applications is between protection of countryside character (Holford Rules, undergrounding presumption in nationally designated areas) and network delivery (CNP status, CP2030 urgency).

CNP status resolves this balance decisively for non-visual impacts. For visual and amenity impacts in nationally designated areas, the reversed undergrounding presumption adds weight on the protection side, but the cost exception and engineering feasibility test provide structural routes back to overhead line consent.

In practice: overhead lines in open countryside are straightforward under EN-5. Lines crossing National Parks or National Landscapes will face undergrounding presumption but can proceed overhead if cost and engineering evidence is presented. CNP status provides additional weight for applicants in all examinations.

Offshore Transmission

EN-5 s.2.12 covers onshore infrastructure associated with offshore transmission: converter stations, cable landfalls, bootstraps (HVDC subsea cables bypassing constrained onshore AC routes), and multi-purpose interconnectors (MPIs). The offshore-side infrastructure is addressed in EN-3 and EN-1.

Bootstraps are a growing category: HVDC subsea links that reinforce the onshore network by routing power around congested onshore corridors. The associated onshore converter stations are large industrial facilities governed by EN-5.

Cross-References

• EN-1: Overarching energy NPS; need case for networks at s.3.3; CNP assessment framework at Part 4
• EN-3: Offshore wind network connection at ss.2.8.34-2.8.43 and 2.8.59-2.8.73
• Planning Act 2008 s.16: NSIP threshold definition
• Electricity Act 1989 s.37: Consent regime for below-threshold lines
• Electricity Act 1989 Schedule 9: Environmental duties (natural beauty, conservation)
• Planning Act 2008 s.35: Secretary of State direction power

Related wiki pages: nps-en-1 | nps-en-3 | planning-act-2008