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:

Source	Example
Solar photovoltaic	PV panels installed on rooftops
Wind	Small-scale wind turbines
Micro-generation	Other micro-generation technologies
Energy storage	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:

Concern	Detail
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.

Warning: A prosumer installation has at least two sources of energy. Even when the mains supply is disconnected, stored energy from batteries or live PV arrays may still be present.

Section 801 - Energy Storage Systems (ESS)

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

Key requirements:

Requirement	Detail
Means of isolation	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
Ventilation	Battery installations must be located in ventilated areas appropriate to the battery chemistry
Thermal management	Must be considered for the battery system
Accessible disconnection	The means of disconnection must be accessible and clearly identified

Battery Safety Considerations

Hazard	Detail
Stored energy, chemical exposure, thermal runaway	Batteries can present hazards from all three sources
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:

Location	Purpose
Main switchboard	Warn of multiple energy sources
Meter position	Warn of multiple energy sources
Consumer unit	Warn of multiple energy sources
Every point of isolation	Warn of multiple energy sources

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

Documentation Requirements

Documentation for prosumer installations must include:

Document	Detail
Type and rating	Of generation equipment
Capacity	Of energy storage systems
Interface protection	Arrangement of the interface protection system
Isolation points	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	Requirement
801.1	Establishes that Part 8 supplements the requirements of Parts 1 through 7
801.411	Requirements for protection against electric shock in prosumer installations
801.514	Labelling requirements for installations with local generation and storage
801.537	Requirements for isolation and switching of generation and storage sources
802.3	Requirements for the interface between the prosumer installation and the public network
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