Part 7 - Special Installations or Locations

Overview

Part 7 of BS 7671 addresses locations and installations where the risk of electric shock or fire is increased beyond that encountered in ordinary installations. Each section identifies a specific type of location and sets out additional or modified requirements that must be applied on top of the general rules found in Parts 1 through 6.

The underlying principle is that certain environments present heightened hazards due to factors such as:

• The presence of water
• Reduced body resistance
• Contact with Earth potential
• The involvement of vulnerable people or animals

Key principle: Part 7 does not replace the general requirements — it supplements them. When designing or inspecting a special location, the electrician must first satisfy all relevant general rules and then apply the additional Part 7 requirements specific to that location.

This part carries a significant exam weighting because it spans many distinct sections, each with its own set of rules, zone definitions, IP ratings, and protective measures.

Key Sections

Section 701 - Locations Containing a Bath or Shower

Section 701 is one of the most frequently examined areas within Part 7. It divides the bathroom into three zones, each with specific requirements.

Zone Definitions

Zone	Description	IP Rating Required
Zone 0	Inside the bath tub or shower basin	IPX7 (immersion protection)
Zone 1	Above Zone 0, up to 2.25m from finished floor level	IPX4 (or IPX5 where water jets are used)
Zone 2	Extending 0.6m horizontally beyond Zone 1	IPX4

Key Requirements

• All circuits serving the location must be protected by a 30mA RCD
• Only SELV at a maximum of 12V AC or 30V DC is permitted in Zone 0
• Socket outlets are not permitted in Zones 0, 1, or 2 (except shaver sockets to BS EN 61558-2-5)
• Supplementary bonding may be omitted where all circuits comply with the conditions in Regulation 701.415.2

Section 702 - Swimming Pools and Other Basins

Swimming pools present extreme risk due to full body immersion and close contact with earthed surfaces.

Zone Definitions

Zone	Description
Zone 0	Interior of the pool basin
Zone 1	Up to 2m horizontally from the pool edge and 2.5m above the floor
Zone 2	A further 1.5m horizontally beyond Zone 1

Key Requirements

• Only SELV not exceeding 12V AC is permitted in Zone 0
• Electrical equipment in Zones 0 and 1 must meet stringent IP ratings
• Socket outlets are generally not permitted within Zone 1
• All metalwork must be connected to supplementary bonding

Section 704 - Construction and Demolition Site Installations

Construction sites require robust temporary supplies designed for harsh conditions.

Key requirements:

• Reduced low voltage (110V) centre-tapped to earth is the standard for portable hand tools, giving 55V to earth
• Socket outlets rated up to 32A must have 30mA RCD protection
• Socket outlets rated above 32A require 500mA RCD protection
• Supplies must withstand harsh mechanical and environmental conditions
• Periodic inspection recommended every 3 months

Section 705 - Agricultural and Horticultural Premises

Agricultural environments involve livestock, which are more susceptible to electric shock than humans.

Key requirements:

• Touch voltage limits are reduced compared to standard installations
• Supplementary bonding is required in locations accessible to livestock
• All socket outlet circuits up to 32A must have 30mA RCD protection
• Fire-risk locations (e.g., barns storing hay) require additional consideration of thermal effects
• Cables must be protected against rodent damage and mechanical impact

Section 712 - Solar Photovoltaic (PV) Supply Systems

Section 712 addresses the installation of PV arrays and their connection to the electrical installation.

Key requirements:

• Appropriate DC isolation must be provided
• Warning labels must be placed at:
  • The main distribution board
  • The meter position
  • Any point where the PV supply can be isolated
• String and array cables must be adequately protected against fault currents
• Cables must be suitable for the environmental conditions on rooftops (UV exposure, temperature extremes)

Important: PV arrays cannot be switched off while exposed to light. This creates unique hazards for installers and maintenance personnel.

Section 722 - Electric Vehicle Charging Installations

Section 722 covers the supply of electricity to electric vehicles.

Key requirements:

• Each charging point must be supplied by an individual circuit
• Minimum protection: 30mA Type A RCD
• A Type B RCD may be required where DC fault current could arise, unless the charger has built-in DC fault protection
• Load management must be considered where multiple charging points share a single distribution board
• The circuit must be rated for continuous duty (the load may be sustained for hours)

Other Notable Sections

• Section 709 (Marinas) — Requires specific arrangements for supplies to vessels, including individual RCD protection for each vessel connection
• Section 710 (Medical locations) — Classified into:
  • Group 0 — No applied parts (e.g., general hospital areas)
  • Group 1 — Applied parts but not vital (e.g., hospital wards)
  • Group 2 — Vital applied parts (e.g., operating theatres) — require IT systems for certain circuits and insulation monitoring devices

Important Regulation Numbers

• Regulation 701.411.3.3 - RCD protection not exceeding 30mA required for all circuits in locations containing a bath or shower
• Regulation 701.415.2 - Conditions under which supplementary bonding may be omitted in bathrooms
• Regulation 701.512.3 - Requirements for wiring systems in zones of bathrooms
• Regulation 702.410.3.4.1 - SELV voltage limits in swimming pool zones
• Regulation 704.410.3.10 - Reduced low voltage requirements for construction sites
• Regulation 705.422.6 - Fire protection measures in agricultural premises
• Regulation 712.411.3.2.1 - Requirements for isolation of PV arrays
• Regulation 722.531.3.101 - RCD requirements for EV charging circuits

Common Exam Topics

• Bathroom zone dimensions and the IP ratings required in each zone
• Maximum SELV voltage permitted in Zone 0 of a bathroom or swimming pool (12V AC)
• Construction site voltage requirements — 110V centre-tapped to earth (55V to earth)
• EV charging RCD type — Type A vs Type B and when each is required
• Which special locations require supplementary bonding and when it can be omitted
• PV labelling requirements and the inability to isolate a PV array from its energy source during daylight
• The principle that Part 7 supplements (not replaces) the general rules

Study Tips

• Memorise the zone dimensions for bathrooms (701) and swimming pools (702). Draw diagrams to reinforce the spatial relationships between zones.
• Learn the IP rating requirements for each zone. Remember that IPX7 applies to Zone 0 (immersion protection) and IPX4 applies to Zones 1 and 2 (splash protection).
• For construction sites, remember the key voltage: 110V centre-tapped to earth providing 55V to earth for portable tools.
• Understand the difference between Type A and Type B RCDs in the context of EV charging and when each is required.
• Do not try to memorise every regulation number across all special locations. Focus on the sections most frequently tested: 701, 702, 704, 712, and 722.
• Always remember that Part 7 requirements are additional to the general rules. The general requirements still apply in every special location.

Related Topics

• Part 4 - Protection for Safety
• Part 5 - Selection and Erection of Equipment
• Part 6 - Inspection and Testing
• Part 8 - Prosumers Installation