Electrical Work Guide for London Homes in 2025: Part P, Full Rewire, 18th Edition Consumer Unit Upgrade, RCBO, AFDD, EV Charger, Solar PV, Kitchen Circuits, and Electrical Costs

Part P Building Regulations notifiable work, full rewire specification, 18th Edition BS 7671 Amendment 3 consumer unit upgrade, RCBO versus RCD versus AFDD specification, and EV charger installation and OZEV grant for London homes in 2025: PART P BUILDING REGULATIONS — ELECTRICAL SAFETY IN DWELLINGS: WHAT PART P COVERS: Approved Document P (ELECTRICAL SAFETY — DWELLINGS) sets the Building Regulations requirements for electrical installation work in residential properties in England; PART P NOTIFIABLE WORK — REQUIRES NOTIFICATION TO BUILDING CONTROL OR SELF-CERTIFICATION BY AN APPROVED COMPETENT PERSON: NOTIFIABLE WORK (requires Building Control notification or competent person self-certification under Part P): a NEW ELECTRICAL CIRCUIT (any new circuit from the consumer unit, regardless of the room it serves); CONSUMER UNIT REPLACEMENT (replacing the consumer unit — known as the fuse board or distribution board — is notifiable); EV CHARGER INSTALLATION (notifiable under Part P from 2022); ELECTRICAL INSTALLATION IN A BATHROOM OR SHOWER ROOM (any new or replacement fixed electrical work in a bathroom is notifiable); SOLAR PV INSTALLATION (notifiable); NON-NOTIFIABLE WORK (can be done by a competent DIYer or non-Part P contractor without notification): like-for-like replacement of sockets, switches, or light fittings on existing circuits (provided they are not in a bathroom, kitchen, or special location); PART P COMPLIANCE — TWO ROUTES: ROUTE 1 — APPROVED COMPETENT PERSON SELF-CERTIFICATION: the electrician is registered with a GOVERNMENT-APPROVED COMPETENT PERSON SCHEME (NICEIC, NAPIT, Elecsa, SELECT in Scotland, or STROMA) and can SELF-CERTIFY the work without Building Control inspection; the scheme issues a CERTIFICATE (ELECTRICAL INSTALLATION CERTIFICATE for new circuits or consumer unit replacement, MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE for additions/alterations to existing circuits) which is sent to the Local Authority Building Control (LABC) and to the homeowner; ROUTE 2 — BUILDING CONTROL APPROVAL: work is notified to the Local Authority Building Control before it starts; Building Control inspects the completed work and issues a Completion Certificate; APPROVED COMPETENT PERSON SCHEME BRANDS IN LONDON RESIDENTIAL IN 2025: NICEIC (the most widely used in London residential — National Inspection Council for Electrical Installation Contracting); NAPIT (National Association of Professional Inspectors and Testers); ELECSA; always ask to see the contractor's SCHEME REGISTRATION CERTIFICATE before work starts and to receive the ELECTRICAL INSTALLATION CERTIFICATE upon completion; FULL REWIRE SPECIFICATION FOR A LONDON VICTORIAN TERRACE IN 2025: a FULL REWIRE involves replacing ALL the wiring, switches, sockets, light fittings, and the consumer unit throughout the property; TYPICAL WIRING SPECIFICATION FOR A FULL REWIRE OF A 3-4 BEDROOM LONDON VICTORIAN TERRACE IN 2025: CABLE TYPE: BS 6004 PVC TWIN AND EARTH CABLE (the standard cable type for fixed wiring in domestic installations — typically 1.0mm² for lighting circuits, 2.5mm² for ring main power circuits, 4.0mm² or 6.0mm² for cooker and shower circuits); ALUMINIUM WIRING ALERT: some London properties built in the 1960s-1970s were wired with ALUMINIUM SINGLE-CORE CONDUCTORS (instead of the standard copper) — aluminium wiring is now considered a fire risk (it oxidises at terminations, causing high resistance joints that can arc and ignite) and should be REPLACED IN FULL during a rewire; RUBBER-INSULATED WIRING (PRE-1966): should be REPLACED IN FULL (the rubber insulation is brittle and electrically unsafe); RING MAIN (RING FINAL CIRCUIT) FOR POWER SOCKETS: the RING MAIN (2.5mm² cable in a ring from the consumer unit, around the floor of each storey, and back to the consumer unit) is the standard method of wiring 13A socket outlets in UK dwellings; each ring main protects approximately 100m² of floor area (GN3 — IET Guidance Note 3); in a 3-4 bedroom London terrace, the ground floor ring main and the first floor ring main are separate circuits from the consumer unit; NUMBER OF SOCKET OUTLETS: modern London residential specifies approximately 8-12 double sockets per reception room, 6-8 per bedroom, and additional dedicated circuits for kitchen appliances (see kitchen circuits below); LIGHTING CIRCUITS: 1.0mm² cable on a 6A MCB; one lighting circuit per floor is standard in a London Victorian terrace (approximately 8-10 light points per circuit); USB SOCKET OUTLETS: INCREASINGLY SPECIFIED IN LONDON RESIDENTIAL BEDROOMS AND HOME OFFICES IN 2025 (e.g., USB-A + USB-C charging integrated into the socket faceplate — MK Logic Plus USB or Legrand Valena USB + Type-C, Screwless flatplate finish most specified in London premium residential in 2025); 18TH EDITION BS 7671 AMENDMENT 3 (2020) CONSUMER UNIT SPECIFICATION: THE CONSUMER UNIT (FUSE BOARD / DISTRIBUTION BOARD) IS THE HEART OF THE ELECTRICAL INSTALLATION — AND CONSUMER UNIT SPECIFICATION HAS CHANGED SIGNIFICANTLY IN RECENT EDITIONS OF BS 7671: AMENDMENT 3 2020 KEY REQUIREMENTS FOR NEW CONSUMER UNITS IN DWELLINGS: ALL CONSUMER UNITS IN DWELLINGS MUST BE ENCLOSED IN A NON-COMBUSTIBLE ENCLOSURE (steel consumer unit): this requirement (introduced to prevent the spread of fire from the consumer unit) means that the ALL-PLASTIC CONSUMER UNITS (which were the dominant product installed in UK dwellings in the 2000s and 2010s) are NO LONGER COMPLIANT FOR NEW INSTALLATIONS; the replacement STEEL CONSUMER UNITS (typically HAGER VML SERIES or WYLEX NHXS SERIES or SCHNEIDER ELECTRIC ACTI9) have become the standard installation in London residential in 2025; RCD PROTECTION (RESIDUAL CURRENT DEVICE): ALL CIRCUITS IN A DWELLING MUST HAVE RCD PROTECTION (30mA RCD — protects against electric shock); split-load consumer unit (half the circuits on one RCD, half on another RCD) is the minimum; RCBO (RESIDUAL CURRENT CIRCUIT BREAKER WITH OVERCURRENT PROTECTION): an RCBO combines the function of an MCB (overcurrent protection) and an RCD (earth fault/residual current protection) into a single device; installing RCBOs on EVERY CIRCUIT (rather than relying on a single split-load RCD for two banks of circuits) is now considered BEST PRACTICE for London residential in 2025 because: IF A CIRCUIT TRIPS AN RCD IN A SPLIT-LOAD BOARD, ALL CIRCUITS PROTECTED BY THAT RCD GO DEAD (loss of lighting or sockets on half the house); WITH RCBOs ON EVERY CIRCUIT: ONLY THE FAULTY CIRCUIT LOSES POWER — everything else stays on; RCBO BRANDS IN LONDON RESIDENTIAL IN 2025: HAGER (most widely installed in London premium residential in 2025); SCHNEIDER ELECTRIC ACTI9 RCBO; WYLEX RCBO; AFDD (ARC FAULT DETECTION DEVICE): an AFDD is a device that detects ARCING FAULTS in the wiring (damaged insulation creating an arc that can ignite a fire — arcing faults are a leading cause of domestic fires in the UK); AFDD REQUIREMENT (BS 7671 AMENDMENT 3): AFDDs are RECOMMENDED (not currently mandatory in England) for HIGHER RISK LOCATIONS: BEDROOM CIRCUITS, CIRCUITS IN OLDER PROPERTIES WITH A HIGHER LIKELIHOOD OF WIRING DAMAGE (i.e., London Victorian and Edwardian properties), and HIGH-VALUE PROPERTIES; RCB RECOMMENDS SPECIFYING AFDDs ON ALL BEDROOM AND LIVING ROOM CIRCUITS IN LONDON RESIDENTIAL RENOVATION PROJECTS — PARTICULARLY IN VICTORIAN AND EDWARDIAN PROPERTIES WHERE THE STRUCTURE AND HIDDEN WIRING ROUTES ARE OF UNCERTAIN CONDITION; AFDD BRANDS IN LONDON RESIDENTIAL IN 2025: HAGER AFDD+RCBO COMBINED UNIT; SIEMENS; EV CHARGER INSTALLATION FOR LONDON HOMES IN 2025: EV CHARGER INSTALLATION IS ONE OF THE FASTEST-GROWING SEGMENTS OF LONDON RESIDENTIAL ELECTRICAL WORK IN 2025 — driven by the rapid growth of ELECTRIC VEHICLE OWNERSHIP in London and the OZEV GRANT (OFFICE FOR ZERO EMISSION VEHICLES — formerly OLEV GRANT): OZEV GRANT IN 2025: the ELECTRIC VEHICLE HOMECHARGE SCHEME (EVHS — ENGLAND) provides a GRANT OF UP TO £350 towards the purchase and installation of a SMART EV CHARGER at a private residence; only OZEV-APPROVED EV CHARGER INSTALLERS (approved under the OLEV/OZEV scheme) and OZEV-APPROVED SMART CHARGERS can be used to claim the grant; SMART CHARGER REQUIREMENT: from 30 June 2022, ALL NEW EV CHARGERS INSTALLED IN THE UK MUST BE SMART CHARGERS (capable of off-peak charging scheduling, ability to communicate with the grid — complying with OZEV Smart Charging Standard); most popular OZEV-approved smart EV charger brands in London residential in 2025: OHME HOME PRO (the most widely installed smart EV charger in London residential in 2025 — integrates with energy tariffs including Octopus Agile for automatic off-peak charging); MYENERGI ZAPPI (the most widely installed solar-diversion smart charger — charges the EV preferentially from solar PV excess before drawing from the grid — important for London homes with solar PV); HYPERVOLT HOME 3 (most specified by approved EV charger installers in London residential in 2025); WALLBOX PULSAR PLUS; OHME EPOD; EV CHARGER CIRCUIT SPECIFICATION: the EV charger requires a DEDICATED 32A CIRCUIT from the consumer unit (2.5mm² or 6.0mm² cable depending on run length and volt-drop calculation); the circuit must be RCD protected (30mA RCD); TN-S EARTHING SYSTEM (the standard earthing system for new installations and for properties connected to a PME/TN-C-S supply where the DNO has confirmed the supply is suitable for EV charging); LOAD MANAGEMENT (IMPORTANT FOR LONDON TERRACE WITH OLD SINGLE-PHASE 60A OR 80A SERVICE FUSE): if the existing DNO CUT-OUT FUSE (main service fuse) is 60A or 80A, adding a 32A EV charger circuit can cause OVERLOAD of the main fuse if the EV is charging simultaneously with other high-demand appliances (electric shower, induction hob, electric oven); LOAD BALANCING DEVICES (such as the Myenergi Harvi or Ohme load balancing feature) monitor the whole-house load and reduce the EV charging rate when the total load approaches the fuse limit.

Solar PV installation, kitchen circuit specification, electrical installation testing and certification (EICR), and electrical costs for London homes in 2025: SOLAR PV INSTALLATION FOR LONDON HOMES IN 2025: SOLAR PV (PHOTOVOLTAIC) SYSTEM INSTALLATION IN LONDON: a SOLAR PV SYSTEM converts sunlight into electricity using solar panels (photovoltaic modules) mounted on the roof; in London, the typical PV SYSTEM FOR A 3-4 BEDROOM TERRACE: SYSTEM SIZE: 3-4 kWp (kilowatt-peak) — approximately 8-10 MONOCRYSTALLINE SILICON PANELS (each panel approximately 365-420 Wp); most popular brands in London residential in 2025: JINKO SOLAR (Tiger Neo N-Type 415-440 Wp — most widely installed panel in London residential in 2025); LONGI SOLAR (HIMO series — second most widely installed); REC GROUP (Alpha series — premium specification); SOLAR PANEL SPECIFICATION FOR LONDON: PANEL EFFICIENCY: 20-23% (for monocrystalline panels — higher efficiency = fewer panels needed for the same output); PANELS ON A SOUTH-FACING PITCHED ROOF AT 35° INCLINATION: optimal orientation for London (51.5°N latitude — optimal tilt angle 32-37°); PANELS ON AN EAST-WEST FACING FLAT ROOF (on a London rear extension): EAST-WEST mounting (split array on both east and west roof slopes of a flat roof with low ballasted tilt frames): lower peak output than south-facing (typically 80-85% of south-facing annual yield) but BETTER SELF-CONSUMPTION (the E-W split generates more evenly through the day, matching the household's morning and evening demand peaks better than a south-facing array that peaks at midday when the house may be empty); LONDON ANNUAL SOLAR IRRADIATION: approximately 900-1,000 kWh/m²/year (the lowest in England — London receives less sun than the South West, South East, or East Anglia; however, solar PV is still economically viable in London and is now the norm on new-build extensions and refurbishments in 2025); INVERTER: the DC output of the solar panels is converted to AC by the INVERTER; BRANDS: FRONIUS PRIMO (most widely installed premium inverter in London residential in 2025); SOLIS (most widely installed budget inverter in London residential in 2025); SMA SUNNYBOY; SOLAR EDGE (incorporates per-panel power optimisers — the most widely installed system for London terraces with shading issues — shading from neighbours' party wall parapets, chimneys, or trees is common in London and SolarEdge with optimisers mitigates shading losses much better than a standard string inverter alone); BATTERY STORAGE FOR SOLAR PV IN LONDON HOMES IN 2025: a SOLAR PV BATTERY STORAGE SYSTEM stores excess solar generation for use in the evening (when the solar panels are not generating but the household demand is highest); BRANDS: TESLA POWERWALL 3 (13.5 kWh — the most widely installed home battery system in London residential in 2025); MYENERGI LIBBI (5-20 kWh modular — integrates natively with the Myenergi Zappi EV charger and Eddi solar diverter); SUNGROW SBR (modular — good value); GIVENERGY (UK-based brand — popular for London residential solar + battery in 2025); BUS GRANT FOR SOLAR PV IN 2025: solar PV is NOT covered by the Boiler Upgrade Scheme — but solar PV + battery may be eligible for 0% VAT (in England, for residential properties — zero VAT rate applied to solar panels, battery storage, and associated equipment from February 2024 through at least 2027); PERMITTED DEVELOPMENT FOR SOLAR PV ON LONDON ROOFS: solar panels on a PITCHED ROOF of a house are PERMITTED DEVELOPMENT (no planning permission required) PROVIDED: panels do not protrude more than 200mm above the roof slope; panels are not installed on a LISTED BUILDING or in a LISTED BUILDING CURTILAGE; panels are not installed on a roof FACING A HIGHWAY (if in a CONSERVATION AREA); always check with the LPA for conservation area properties; PLANNING PERMISSION IS REQUIRED FOR: FLAT-ROOF SOLAR (above 1m of the roof surface); SOLAR ON A LISTED BUILDING; SOLAR IN A WORLD HERITAGE SITE; KITCHEN CIRCUIT SPECIFICATION FOR LONDON HOMES IN 2025: THE KITCHEN IS THE HIGHEST-ELECTRICAL-DEMAND ROOM IN A LONDON HOME AND REQUIRES CAREFULLY DESIGNED DEDICATED CIRCUITS — THIS IS FREQUENTLY UNDER-SPECIFIED IN LONDON RESIDENTIAL REFURBISHMENTS: REQUIRED DEDICATED KITCHEN CIRCUITS IN A LONDON RESIDENTIAL KITCHEN IN 2025 (BS 7671 MINIMUM): COOKER CIRCUIT: 6.0mm² cable on a 32A or 40A MCB/RCBO — for an ELECTRIC RANGE COOKER (7-12 kW) or INDUCTION HOB (5-7 kW) + SEPARATE ELECTRIC OVEN (2-3 kW); for a GAS HOB + ELECTRIC OVEN: a 3kW oven can be fed from a 32A cooker switch — 6.0mm² cable; DISHWASHER CIRCUIT: 2.5mm² on a 20A MCB/RCBO (dedicated circuit — washing machine and dishwasher should each have their own circuit as they contain heating elements running for long periods); WASHING MACHINE CIRCUIT: 2.5mm² on a 20A MCB/RCBO (dedicated); FRIDGE-FREEZER: can be on the kitchen ring main but ideally on a SEPARATE DEDICATED CIRCUIT (prevents food spoilage if the ring main trips for any reason); RING MAIN FOR GENERAL KITCHEN SOCKETS: 2.5mm² on a 32A RCD/RCBO (note: under BS 7671 18th Edition, the kitchen ring main must be RCD protected); UNDER-COUNTER AND COUNTER-TOP APPLIANCE SOCKETS (typically 6-10 double switched sockets in a modern London kitchen above the counter): on the kitchen ring main; REFRIGERATION (WINE COOLER, INTEGRATED FRIDGE): consider a separate dedicated circuit from the consumer unit (4mm² on 20A MCB); IMPORTANT NOTE ON KITCHEN CIRCUITS: INDUCTION HOB + ELECTRIC OVEN + DISHWASHER + WASHING MACHINE running simultaneously is a COMBINED LOAD OF APPROXIMATELY 15-25 kW — which is close to or above the CAPACITY OF A STANDARD DOMESTIC 63A OR 80A CUT-OUT FUSE; IN A LONDON KITCHEN REFURBISHMENT WITH FULL APPLIANCE FIT-OUT, THE ELECTRICAL DESIGN MUST INCLUDE A DIVERSITY CALCULATION TO CONFIRM THE SUPPLY FUSE IS NOT OVERLOADED; ELECTRICAL INSTALLATION CONDITION REPORT (EICR): a CONDITION REPORT (EICR) is the standard periodic inspection and testing report for an existing electrical installation; AN EICR IS REQUIRED: every 10 years for owner-occupiers; every 5 years or on change of tenancy for PRIVATE RENTED PROPERTIES (mandatory from 2020 under the ELECTRICAL SAFETY STANDARDS IN THE PRIVATE RENTED SECTOR REGULATIONS 2020); when buying or remortgaging a London property (mortgage lenders increasingly require a current EICR within 5 years); EICR OUTCOME CODES: C1: DANGER PRESENT — REQUIRES IMMEDIATE REMEDIAL ACTION; C2: POTENTIALLY DANGEROUS — URGENT REMEDIAL ACTION REQUIRED; C3: IMPROVEMENT RECOMMENDED (advisory — not a fail but a suggestion); FI: FURTHER INVESTIGATION REQUIRED; AN EICR THAT CONTAINS ANY C1 OR C2 CODE IS A FAIL — meaning the installation is UNSATISFACTORY and remedial work is required before a SATISFACTORY EICR CAN BE ISSUED; ELECTRICAL COSTS IN LONDON IN 2025: FULL REWIRE (3-4 BEDROOM VICTORIAN TERRACE — INCLUDING CONSUMER UNIT, ALL CABLE, SOCKETS, SWITCHES, AND EARTHING — NOT INCLUDING LIGHT FITTINGS OR DECORATION): approximately £6,000-£15,000 (depending on property size, access difficulty, and specification level — e.g., premium screwless flatplate finish increases cost significantly); CONSUMER UNIT UPGRADE (HAGER OR WYLEX STEEL CONSUMER UNIT + RCBO ON EVERY CIRCUIT — SUPPLY AND FIT — NOT INCLUDING REMEDIAL WORKS IDENTIFIED DURING INSTALLATION): approximately £600-£1,500; EV CHARGER INSTALLATION (32A OHME HOME PRO OR MYENERGI ZAPPI — SUPPLY AND INSTALL — INCLUDING CABLE RUN TO CONSUMER UNIT — BEFORE OZEV GRANT): approximately £800-£1,500 (net cost after £350 OZEV grant: approximately £450-£1,150); SOLAR PV SYSTEM (3-4 kWp — 8-10 JINKO TIGER NEO PANELS — SOLAREDE INVERTER WITH OPTIMISERS — SUPPLY AND INSTALL — INCLUDING DNO G99 APPLICATION IF REQUIRED — 0% VAT): approximately £5,000-£9,000; SOLAR PV + TESLA POWERWALL 3 BATTERY (13.5 kWh — ADD TO ABOVE): add approximately £8,500-£11,000; EICR (ELECTRICAL INSTALLATION CONDITION REPORT — 3-4 BED TERRACE): approximately £150-£400; ADDITIONAL SOCKET OUTLET (SURFACE-MOUNTED — EXISTING CIRCUIT — MINOR WORKS): approximately £80-£200 per socket; ADDITIONAL SOCKET OUTLET (CHASED-IN — NEW CIRCUIT — FULL DECORATION NOT INCLUDED): approximately £150-£350 per socket; FIRST FIX ELECTRICAL (NEW 3-4 BED EXTENSION OR REFURBISHMENT — SUPPLY AND FIT ALL CABLE — NOT INCLUDING SECOND FIX FITTINGS): approximately £1,500-£5,000.