Safe EV charging depends on a correctly designed earthing arrangement, adequate protective bonding where required, and residual current protection suitable for the charger and circuit. Many UK homes need consumer unit upgrades before a wallbox is added because older boards lack appropriate devices. A survey that skips board condition is not a complete survey.
Why EV circuits stress weak boards
Chargepoints are high-load, regularly used outdoor circuits. They expose missing bonding, worn main switches and outdated RCD arrangements that a lightly used socket circuit might not reveal. Installers assess the intake, earthing type and board compatibility before promising a one-day fit.
If the quote rises after survey because the board must change, that is often responsible practice rather than bait pricing, provided the original caveats were clear.
- Photograph the consumer unit labels for early discussion.
- List any recent electrical fail notices from sales surveys.
- Expect functional testing, not only visual comments.
RCD types and manufacturer instructions
EV equipment can impose specific residual current device requirements. Using the wrong type can nuisance-trip or fail to provide the intended protection. Manufacturer instructions and BS 7671 guidance drive the selection; homeowners should ask which device type is proposed and why.
Double RCD problems and selectivity issues are technical design points. If an installer cannot explain the protective device strategy in plain English, press for clarity before authorising work.
Bonding and extraneous conductive parts
Main protective bonding of incoming metallic services may need verification or upgrading as part of making the installation safe. This is separate from the charger brand choice and can affect metal pipework areas far from the driveway.
Outdoor metal posts, fences and structural steel near the chargepoint may also influence design. The installer should assess what is present rather than applying a one-line template.
What good handover looks like
Certificates should identify circuit details, protective device ratings and test results. You should also receive guidance on isolation points and what to do if the RCD trips repeatedly.
Repeated unexplained trips after install deserve a return visit, not a suggestion to keep resetting forever.
- Keep before-and-after board photos.
- Confirm outdoor isolator location and labelling.
- Ask how open-PEN protection interacts with the earthing design where relevant.
Frequently asked questions
Why do installers often want to replace the consumer unit?
Older boards may lack suitable protective devices or spare ways for a dedicated EV circuit. Replacement can be the cleanest way to meet modern safety expectations.
Is an RCD the same as a circuit breaker?
No. Circuit breakers protect against overcurrent. RCDs detect residual current faults. EV circuits typically need coordinated protection, not one device doing every job by accident.
Can bonding work add unexpected cost?
Yes. If bonding is missing or inadequate, copper runs and access to stopcocks or service entries can add labour. It is still part of a safe installation.
Should the charger share an upstairs socket RCD?
Dedicated, correctly specified protection is the normal design approach. Sharing inappropriate existing devices is a common poor practice to refuse.
Core buying guides
Start with these high-intent guides, then dig into the rest of the library.
Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local EV Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.