Part 8 - Prosumers Installation

Overview

Part 8 is one of the newest additions to BS 7671, introduced as part of Amendment 2 to the 18th Edition. It addresses the growing prevalence of prosumer electrical installations, where the end user both consumes electricity from the public supply network and produces electricity through local generation sources.

The term “prosumer” combines “producer” and “consumer,” reflecting this dual role. Common generation sources include:

• Solar photovoltaic (PV) panels
• Wind turbines
• Other micro-generation technologies
• Battery energy storage systems

The need for Part 8 arose from the rapid increase in installations that incorporate local energy generation and battery storage. These installations introduce hazards and design considerations that go beyond the scope of a conventional consumer installation.

Key principle: Part 8 establishes requirements to ensure that such installations remain safe for the user, for maintenance personnel, and for the operatives of the electricity distribution network.

Key Sections

Section 801 - General Requirements for Prosumer Installations

Section 801 sets out the general safety principles that apply to any installation where on-site generation is connected alongside a supply from the public distribution network.

Key concerns addressed:

• Safe disconnection — The installation must be arranged so that it can be safely isolated for maintenance work
• Network safety — Local generation must not export energy into a network that has been de-energised for work purposes (critical for the safety of distribution network operatives)
• Supplementary nature — Part 8 applies in addition to the requirements of Parts 1 through 7, following the same supplementary principle used by Part 7 for special locations (Regulation 801.1)

The Core Hazard

A prosumer installation has at least two sources of energy (the grid supply and local generation/storage). This dual-source arrangement creates additional hazards that do not exist in a conventional single-source installation.

Section 801 - Energy Storage Systems (ESS)

Energy storage systems, predominantly battery installations, are integral to many prosumer setups.

Key requirements:

• Appropriate means of isolation must be provided and clearly identified
• Clear labelling must warn that stored energy may be present even when the main supply is disconnected
• Battery installations must be located in ventilated areas appropriate to the battery chemistry
• Thermal management must be considered for the battery system
• The means of disconnection must be accessible and clearly identified

Battery Safety Considerations

• Batteries can present hazards from stored energy, chemical exposure, and thermal runaway
• Ventilation requirements vary by battery chemistry (e.g., lead-acid vs lithium-ion)
• Fire suppression considerations may be needed for larger installations

Section 802 - Requirements for Connection to the Public Supply Network

Section 802 focuses on the interface between the prosumer installation and the public electricity supply.

Anti-Islanding Protection (Regulation 802.4)

Islanding occurs when a local generator continues to feed into the network during a power cut. This is extremely dangerous because:

• Network operatives may be working on what they believe to be a de-energised supply
• They could receive a fatal electric shock from an unexpected energy source

The installation must include an interface protection system that automatically disconnects the generation source when loss of mains supply is detected.

Labelling Requirements (Regulation 801.514)

Part 8 places strong emphasis on labelling. Durable warning labels must be placed at:

• The main switchboard
• The meter position
• The consumer unit
• Every point of isolation

All labels must advise that the installation has more than one source of energy.

Documentation Requirements

Documentation for prosumer installations must include:

• The type and rating of generation equipment
• The capacity of energy storage systems
• The arrangement of the interface protection system
• Details of isolation points for all energy sources

This information is essential for anyone carrying out future inspection, testing, or maintenance.

Important Regulation Numbers

• Regulation 801.1 - Establishes that Part 8 supplements the requirements of Parts 1 through 7
• Regulation 801.411 - Requirements for protection against electric shock in prosumer installations
• Regulation 801.514 - Labelling requirements for installations with local generation and storage
• Regulation 801.537 - Requirements for isolation and switching of generation and storage sources
• Regulation 802.3 - Requirements for the interface between the prosumer installation and the public network
• Regulation 802.4 - Anti-islanding provisions to prevent energisation of the network during outages

Common Exam Topics

• The definition of a prosumer and why Part 8 exists
• Labelling requirements — where warning notices must be placed and what they must convey
• The concept of islanding and why anti-islanding protection is required
• Isolation requirements for energy storage systems, including accessible means of disconnection
• The relationship between Part 8 and Section 712 (solar PV) — both apply to grid-connected PV installations
• The principle that Part 8 supplements rather than replaces the general rules
• Ventilation and safety requirements for battery installations

Study Tips

• Start by understanding the core concept: a prosumer installation has at least two sources of energy, and this dual-source arrangement is what creates additional hazards.
• Focus on labelling requirements. Know where warning labels must be placed and what information they must convey. This is a straightforward area where marks are easily gained.
• Understand the concept of islanding and why it is dangerous. If a local generator continues to feed into the network during a power cut, operatives working on the network could receive a fatal shock from what they expect to be a dead supply.
• Remember that Part 8 works alongside Section 712 for solar PV installations. If a PV system is grid-connected with battery storage, both Section 712 and Part 8 apply.
• Do not overlook energy storage systems. Battery installations require proper ventilation, isolation, and labelling, and these requirements are testable.
• Part 8 is relatively short compared to other parts of the standard. Reading it in full is achievable and recommended.

Related Topics

• Part 7 - Special Installations or Locations
• Part 1 - Scope, Object and Fundamental Principles
• Part 4 - Protection for Safety
• Part 5 - Selection and Erection of Equipment