WhattheInstallationInvolves
Most people buying an electric vehicle think about range, charging speed, and monthly fuel savings — not about whether their consumer unit has a spare 32A way or what earthing arrangement the distribution network uses at their property. That gap between purchasing an EV and understanding what the home electrical system actually needs first is where installations stall, surveys reveal unexpected costs, and OZEV grant eligibility is sometimes lost before a cable is run.
The starting point is your consumer unit. An EV charger draws a continuous 32A load — the equivalent of a large electric shower running for however many hours your vehicle charges. A modern consumer unit with a spare way is the ideal scenario, and the new circuit drops in cleanly. An older unit without spare capacity, or one that uses rewirable fuses rather than MCBs, will need upgrading before the charger can be installed.
Smart charging is mandatory for all new residential EV chargepoints — any installer offering a non-smart unit is offering non-compliant equipment. The OZEV EVHS grant of up to £350 is applied by the installer on your behalf, but only OZEV-approved installers using OZEV-approved charger models can do this. Confirm both before you book.
Consumer Unit Readiness
A home EV charger needs a dedicated 32A radial circuit. A modern consumer unit with RCBO protection and a spare way installs cleanly; older units with rewirable fuses or no spare capacity require upgrade work first.
Earthing Arrangement
TN-C-S, TN-S, and TT earthing systems each have different implications for EV charger selection and protective device requirements. The installer confirms this at survey — before installation day.
OZEV Grant Eligibility
Up to £350 off installation via the EVHS grant — applied by OZEV-approved installers only. Confirm the installer's OZEV approval number and check the chosen charger appears on the approved equipment list before booking.
Part P Certification
EV charger installation is notifiable under Part P Building Regulations. An Electrical Installation Certificate at handover is the legal certification document — without it, the installation is not properly certified.
Consumer Unit, Earthing, and Grant Eligibility
Your home's earthing arrangement matters more for EV charging than for most domestic additions. TN-C-S (PME) is the most common UK domestic arrangement, but some properties — typically older homes in rural areas — are on a TT system where the earth is provided via an electrode at the property rather than a metallic return from the distributor. For PME supplies, there are specific considerations around voltage rise on the earthed conductor under fault conditions; for TT properties, the charger must have built-in protection appropriate to the earthing arrangement. Your installer should identify the earthing system at survey. If they don't mention it, ask.
Each circuit on a modern consumer unit is typically protected by an RCBO — a combined MCB and RCD in a single device — which gives individual fault protection without tripping the whole board. Older boards may use a single RCD covering multiple circuits, meaning a fault on the EV circuit could trip other loads. If your consumer unit is more than 15–20 years old or lacks individual RCBO protection, the EV installation is a good moment to address the whole board. For landlords, the OZEV landlord scheme covers up to £350 per socket for up to 200 sockets per application — a separate route from the homeowner EVHS grant, and worth confirming eligibility before committing to an installation programme.
Consumer Unit and Grant Specifications
Consumer Unit Requirements
- RCD/RCBO standard
- RCBO per circuit preferred; dual RCD acceptable on modern boards
- Spare ways required
- Minimum 1 spare 32A way for dedicated EV circuit
- Age/condition threshold
- Units with rewirable fuses or no spare capacity require replacement or upgrade before installation
- EV circuit type
- Dedicated 32A radial circuit from consumer unit to charger location
OZEV Grant & Smart Charger Rules
- EVHS grant (homeowner)
- Up to £350 off a home charger installation
- Landlord scheme
- Up to £350 per socket, up to 200 sockets per application
- Smart charger mandate
- EV Smart Charge Points Regulations 2021 — mandatory for all new domestic installations in England, Wales, and Scotland
- Tethered vs untethered
- Both types eligible; must meet smart charger specification and appear on OZEV-approved equipment list
- Grant application route
- Applied by OZEV-approved installer — no separate homeowner application
What the Installation Survey Covers
- 01Consumer unit condition and spare circuit capacity assessment
- 02Earthing arrangement identification (TN-S, TN-C-S/PME, or TT) and protective device requirements
- 03Existing cable route survey from consumer unit to intended charger location
- 04Smart charger compliance and OZEV-approved equipment confirmation
- 05Part P Building Regulations notification and Electrical Installation Certificate at completion
Common Installation Complications
TN-C-S earthing upgrade required
Challenge
Properties supplied via PME (TN-C-S) earthing sometimes present conductor imbalance risks at the charger location that require additional earthing measures.
Solution
Installer confirms earthing arrangement at survey; where required, a supplementary earth electrode or charger with integral protection is specified before installation proceeds.
Consumer unit too old or no spare capacity
Challenge
Older consumer units with rewirable fuses, no spare MCB ways, or inadequate RCD protection cannot accept a new 32A EV circuit without prior upgrade work.
Solution
Consumer unit replacement or upgrade is scoped and costed at survey — not discovered on installation day. Combining the upgrade with the EV installation brings the whole board to current standards.
Grant eligibility lost due to non-approved installer or equipment
Challenge
Only OZEV-approved installers using OZEV-approved charger models can apply the EVHS grant. Non-approved installers or equipment choices made before checking eligibility can forfeit the £350.
Solution
Confirm installer OZEV approval number and verify the chosen charger model on the OZEV-approved equipment list before booking installation — retrospective grant applications are not possible.
Six Steps Before You Book
Step 01
Check your consumer unit before booking an installation survey. Count the spare ways
if the unit is full, or uses rewirable fuses, flag this to the installer before the survey so they can cost the full scope. Modern consumer units with spare ways mean the charger circuit installs cleanly; older units may need work first.
Step 02
Identify your earthing system. Look for the main earthing terminal near your consumer unit and check whether there is a green-and-yellow earth cable running to an earth rod at the property (TT system) or whether the earth is connected to the supply cable sheath or meter tails (TN-S or TN-C-S). If you cannot identify it, tell the installer
they should confirm it during the survey.
Step 03
Choose a smart charger model before booking installation
not after. OZEV-approved charger models are listed on the OZEV website. Selecting an approved model before the survey ensures the grant application runs smoothly and there are no equipment compatibility issues on the day.
Step 04
Confirm the installer is OZEV-approved before booking. Only OZEV-approved installers can apply the EVHS grant on your behalf. Ask for their OZEV installer number and check it against the OZEV approved installer list. If they can't provide it, the grant won't be applied at installation
and retrospective applications are not possible.
Step 05
Ask about cable routing during the survey, not on installation day. The 32A cable route from consumer unit to charger location
through the house, into the garage, or across an external wall — involves decisions about containment, drilling, and finish that are worth agreeing in advance. Unexpected routes add cost and time on the day.
Step 06
Request the Electrical Installation Certificate at handover. This is the Part P certification document
it confirms the installation is compliant, certified through an approved scheme, and notified correctly. File it with your property documents alongside any other electrical certificates.
Key Takeaways
- 01A home EV charger needs a dedicated 32A radial circuit — check your consumer unit has a spare way before booking; if not, unit work may be needed first
- 02Smart chargers are mandatory for new residential installations — any installer offering a non-smart unit for a new installation is offering non-compliant equipment
- 03OZEV EVHS grant is up to £350 off installation; landlords use a separate scheme covering up to 200 sockets — confirm with an OZEV-approved installer before booking
- 04Your earthing arrangement (TN-S, TN-C-S/PME, or TT) affects charger selection and protective device requirements — the installer should identify it during the survey
- 05EV charger installation is notifiable under Part P — you must receive an Electrical Installation Certificate at handover; no certificate means the work is not properly certified
- 06OZEV-approved installer status matters: only approved installers can apply the grant on your behalf — check the OZEV approved installer list before booking
Client Testimonial
Most home EV charger installations are straightforward — a spare way in the consumer unit, a clean cable route, a smart charger on the approved list. The survey is where edge cases surface. Book the survey before you book the installation date.
Book Early, Not After
A home EV charger installation is not the most technically demanding electrical project, but it involves more than the marketing suggests. Consumer unit capacity, earthing arrangements, smart charger compliance, and Part P certification all need to be in order for the installation to be correct, compliant, and covered by the OZEV grant. None of these are barriers — they are engineering checks that a competent, OZEV-approved installer carries out as part of a proper installation.
The pre-installation survey is where the specifics of your property's electrical system are assessed. A thorough survey covers consumer unit capacity and condition, earthing system identification, cable route planning, and confirmation of OZEV grant eligibility. It should take 30–45 minutes and produce a written scope and quotation that reflects the actual work required, not a generic charger price that later attracts add-on charges for the consumer unit work that was always going to be needed.
If you are buying an EV in the near future, the practical step is to book a survey with an OZEV-approved, NICEIC-registered installer before your vehicle arrives — not after. Installation lead times vary, and having the charger ready when the car arrives is significantly more convenient than using public charging while you wait for a slot.
