Will my home electrics take a 7kW EV charger?

In most modern UK homes (post-2008) yes — a 7kW EV charger draws around 32A and fits comfortably alongside typical household loads on an 80-100A supply. Older homes (pre-2000) may need a consumer unit upgrade or supply assessment. Send the installer a photo of your consumer unit upfront to confirm.

How do I know what size my main supply fuse is?

Look at the sticker or label on your incoming service head (the box where the cable enters before the meter) or main switch on your consumer unit. It typically shows 60A, 80A, or 100A. Don't open the service head — it's sealed by the DNO.

What's a consumer unit upgrade and how much does it cost?

Replacing your fuse box with a modern enclosure with RCDs, RCBOs, and adequate ways for new circuits. Typically £300-£600 for a standard domestic upgrade. Sometimes required to fit a new EV charger circuit if your existing unit is full, old, or non-compliant.

What earthing arrangement does my house have?

Most modern UK homes have TN-C-S (PME) earthing — protective multiple earthing where the supplier provides the earth via the neutral conductor. Older homes may have TN-S (separate earth) or TT (local earth rod). The installer confirms on survey; it affects EV charger model choice.

Why does PME earthing matter for EV chargers?

Per BS 7671 Section 722, PME earthing is restricted for outdoor EV chargers because of a rare fault condition where a broken neutral conductor could energise the car body. Modern smart chargers (Zappi, Ohme, Easee, Hypervolt, Wallbox flagship models) include PEN-fault detection to handle this safely. Without it, an earth rod is fitted.

Can I install an EV charger on an old fuse box?

Usually not without upgrading. Pre-2008 fuse boxes typically lack adequate RCD protection or modern Type A/B RCBO capability required by BS 7671 Section 722. The installer will normally quote a CU upgrade (£300-£600) alongside the EV charger install.

Will Western Power upgrade my supply for free for an EV?

Often yes, if your existing supply is 60A or under. Western Power Distribution offers free upgrades to 100A single-phase for EV charger installations in many cases, subject to assessment. Upgrades to three-phase typically cost £3,000-£10,000 and aren't covered.

Do I need an EICR before fitting an EV charger?

Not strictly required, but recommended if your last electrical inspection was more than 5-10 years ago. An EICR (Electrical Installation Condition Report, around £150-£250) confirms your wiring is safe and identifies any underlying issues that should be fixed before adding a new EV circuit.

Can I add an EV charger to a flat?

Yes if you have an allocated off-street parking bay. The install routes from a sub-main supply (usually from the building's electrical riser to a meter box near your bay). Permission from the freeholder/managing agent is required — and you may qualify for the £500 OZEV grant for flat-owners.

Will My Electrics Take an EV Charger? Consumer Unit Guide

A common surprise on EV charger install day: the £900 quote becomes £1,400 because the installer discovers your consumer unit is full, your supply is 60A not 100A, or your earthing arrangement needs an extra rod. None of these are showstoppers — but they cost real money and time. This guide walks you through the checks you can do before booking, so you get accurate quotes upfront and no surprises on the day.

Why this matters

The installer's quote breaks down into three parts:

The charger hardware (typically £400-£900)
The standard installation labour (£400-£500)
Site-specific extras (can be £0 or can be £600+)

The "site-specific extras" are where homeowners get caught off-guard. Knowing what to check before survey day means accurate quotes and competitive comparison between installers.

The four things that drive site-specific extras

1. Consumer unit (CU) condition

Your CU needs to:

Have at least one spare way (slot for the EV charger's MCB or RCBO)
Have functioning RCDs (residual current devices, the Test-button switches) on the relevant circuits
Be modern enough to accept a Type A or Type B RCD/RCBO for the EV circuit (BS 7671 Section 722)
Not have any unresolved compliance issues from a recent EICR

If any of these fail, you need a CU upgrade (around £300-£600) or a split-board solution.

2. Main supply fuse rating

UK home supplies are typically 60A, 80A, or 100A single-phase. The fuse rating limits how much electricity the house can draw simultaneously.

100A: Standard since around 2008. Comfortably accommodates a 7kW EV charger (32A) plus typical home load.
80A: Common in 1990s-2000s housing. Usually fine for 7kW EV charger; depends on other loads.
60A: Older homes. May require DNO supply upgrade (free from Western Power if eligible) or load-management hardware.
Under 60A: Very old; needs DNO assessment.

3. Earthing arrangement (TN-S, TN-C-S/PME, TT)

Per BS 7671:2018+A2:2022 Section 722, EV chargers have specific requirements for each earthing system. Most Cornwall homes are on TN-C-S (PME) — which restricts outdoor EV chargers unless the charger has built-in PEN-fault detection (most modern smart chargers do — Zappi, Ohme, Easee, Hypervolt, Wallbox all have it on their flagship models). If not, an earth rod is fitted (+£150-£300).

TN-S and TT systems have their own requirements but are generally simpler.

4. Cable route length and routing complexity

Standard quotes typically include 5-10m of cable. Beyond that, each metre costs £15-£30 + labour. Routes through cavity walls, under suspended floors, across lofts, through paving, or around obstacles add labour time. Long routes can add £150-£400.

How to check your consumer unit

Step-by-step (covered in detail in the HowTo schema above):

Locate the CU (usually hallway, under stairs, garage, or external cupboard)
Open the front cover — don't touch wiring; just remove the plastic cover
Photograph the row of switches and labels
Count spare ways (blank slots with covers)
Identify if there's an RCD (large switch with Test button) or RCBOs (smaller individual combination units)
Note the age of the CU — modern (post-2008) usually has metal or plastic enclosure with rows of double-pole switches; older has black bakelite or single-pole switches

How to check your supply fuse

Look at the sticker or label near your incoming service head — the place where the National Grid/Western Power cable enters your house, before the meter. It usually shows the fuse rating (60A, 80A, 100A). If you can't find a sticker, it's usually a black box with the meter alongside.

Don't open the service head — that's sealed by the DNO. Just read any visible labels.

How to check your earthing

The sticker on the service head or near the main switch in the CU often shows the earthing type:

TN-S: Older system; separate earth conductor from supplier
TN-C-S (PME): Most common in modern UK homes; protective multiple earthing
TT: Less common; uses local earth rod

If unsure: leave it for the installer's survey. Most charger brands have PME-compatible models which don't need extra earthing modifications.

Cornwall-specific considerations

Granite cottages — Cable runs often longer than the standard quote allowance due to thick stone walls. Budget +£100-£300 for routing.
Older properties (pre-1980) — Higher chance of needing CU upgrade. Photograph everything early.
Rural properties on private supply — Some farms and remote properties have non-standard supply arrangements. Specialist install required.
Conservation areas — External cable runs may need to be in surface conduit rather than buried, depending on conservation officer requirements. Slight cost premium.

What costs what to fix

Issue	Cost to resolve
Full CU (no spare way)	£300-£600 CU upgrade OR £80-£200 split-board
Old CU with no RCD	£400-£700 CU upgrade
60A or lower supply fuse	Free DNO upgrade (if approved) OR £150-£300 load management hardware
PME earthing on outdoor charger	£0 if charger has PEN-fault detection; +£150-£300 for earth rod
Long cable run (over 10m)	£100-£400 depending on route
Detached garage / outbuilding	£300-£800 (trenching, ducting)

The pre-quote checklist

Before booking surveys with installers, gather:

Photo of consumer unit (cover open, all switches visible)
Photo of incoming service head and meter (with fuse rating sticker if visible)
Measured cable route distance from CU to charger location
Photo of intended charger location (with any obstacles in view)
Note of any recent electrical work (rewire, CU upgrade, EICR)

Send all of this with your quote request. Installers love it because it cuts their survey time; you love it because the quote is accurate.

Ready for an EV charger quote based on your actual site conditions? Submit your postcode with the photos above, and we'll match you with a vetted Cornwall OZEV-approved installer who'll quote properly upfront.

Disclosure

EV Charger Cornwall is a lead-gen service. The checks in this guide are visual only — any actual electrical work must be done by a competent person registered under Part P (NICEIC, NAPIT, ELECSA, Stroma).