The first question a good EV installer answers, before quoting. Phase, spare ways, main switch rating and RCD protection decide whether your board can carry a charger or needs an upgrade first, and why a missing load check leads to nuisance tripping or an unsafe install.
The first question a good installer answers is not which charger you want. It is whether your switchboard can carry one. An EV charger is a continuous high load, and the board has to be checked before a single product is quoted. This guide covers the four checks that decide the answer, and why skipping them causes tripping or an unsafe install.
The four checks before any quote
Each of these is a yes-or-no the installer should confirm at your board before talking price. A quote that names a charger without naming your board has skipped the part that matters.
Phase. Single phase or three phase. This decides whether you can run 7kW or 22kW at all.
Spare ways. Whether the board has room for the new dedicated circuit, or needs to be extended or upgraded.
Main switch rating. Whether your incoming supply can carry the charger on top of your existing peak load.
RCD protection. Whether the board has residual current protection, which a compliant charger circuit requires.
Why a missing load check bites later
A charger draws its full current for hours at a time. That is different from a kettle or an oven, which spike and stop. If the board cannot carry that sustained load on top of everything else, you get nuisance tripping when the air conditioner and the charger run together, or worse, an install that sits over capacity without tripping at all. The load check is a short calculation: add the charger to your measured peak demand and confirm the supply and board can take it. It costs the installer a little time and saves you a service call and a fire risk. A quote that skips it is cheaper for exactly that reason.
We check the phase, the spare ways, the main switch and the RCDs before we quote a charger. The cheap quote names a charger and never looks at your board.
When the board needs work first
If the check finds no spare way, no RCD protection, or a main switch too small for the added load, the board needs attention before the charger goes in. That is not an upsell; it is the difference between a safe install and a hazard. The honest version prices it as a line in the same quote. The cheap version installs onto an unsuitable board and the upgrade becomes a mid-job surprise, or never happens at all. See what triggers a switchboard upgrade for the signs your board is due.
Use the switchboard scorecard
Before you book, the switchboard scorecard on our /pricing page walks you through the four checks so you arrive at quotes already knowing your board's state. Once the board is confirmed, the next decision is the charging rate. Read 7kW versus 22kW EV charging to choose between single and three phase.
Your switchboard, not the charger, decides what is possible and what is safe. Answer the four checks first and the rest of the EV decision becomes simple. Skip them and you are buying a problem you will pay to fix.
Common questions
How do I know if my switchboard can take an EV charger?
A good installer checks four things before quoting: your supply phase, whether the board has a spare way, the main switch rating, and whether RCD protection is present. The reason all four matter is that a charger is a continuous high load, and a board that cannot carry it will either trip or be unsafe. Next step: ask for the switchboard scorecard on our /pricing page or book a board check before accepting any charger quote.
What happens if the installer skips the load check?
You get nuisance tripping, an overloaded board, or an install that is unsafe under continuous load. The reason is that the charger competes with the rest of your home for capacity the board may not have. Next step: insist the quote states your main switch rating and spare capacity, and walk away from any quote that does not mention your board at all.
Do I need three-phase power for an EV charger?
Not for a standard 7kW charger, which runs on single phase and charges most EVs overnight. Three-phase is only needed for 22kW charging. The reason single phase suits most homes is that overnight charging has hours to work with, so the higher rate is rarely necessary. Next step: read our 7kW versus 22kW guide before deciding which charger to buy.
Will I need a switchboard upgrade for the charger?
Sometimes, if your board has no spare way, no RCD protection or a main switch too small for the added load. The reason it comes up often is that older boards were never sized for a continuous EV load. Next step: get the board check done first so any upgrade is priced as a line in the quote, not sprung on you mid-install.