Updated
Told Your Supply Will Not Take A 7kW Charge Point
The survey came back saying the incoming supply is too small, or that the charge point will have to be limited.
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What's happening?
Every house has one fuse it cannot exceed: the service cutout fuse the network operator installed where the supply enters, usually 60A, 80A or 100A. A charge point at 7.4kW draws around 32A of that on its own, for hours, at exactly the times a house is already busy — evening cooking, a shower, an immersion. The installer's job at survey is to work out whether your existing maximum demand plus 32A stays under the cutout, and there are three honest answers. It fits, in which case nothing more is needed. It fits only with load management, where a sensor clamped round the incoming tails tells the charge point to back off when the house draws more, which is now the normal way of fitting a full-power unit to a modest supply. Or it does not fit, in which case either the charge point is limited to a lower current or the supply itself has to be upgraded by the network operator. Being told any of the three is a survey doing its job, not an installer talking you out of a sale.
What usually causes it?
- A 60A service cutout, common in older housing, leaving little headroom once the house is in normal use
- Electric cooking, an electric shower and an immersion heater already accounting for much of the available current
- A second high-load addition such as a heat pump fitted since the supply was sized
- Meter tails or a consumer unit too small to take another 32A circuit without being uprated
- A shared or looped service, where one cutout feeds two properties and neither can have full capacity
- A flat or converted house on a sub-main from a landlord's supply rather than its own service head
Is it dangerous?
Fitting a charge point that the supply cannot carry is genuinely unsafe, which is why the assessment exists. Overload does not usually announce itself — the cutout fuse either blows, taking the whole house out, or the tails and cutout run hot for years first. Never let anyone fit a charge point without a maximum demand assessment, and never let anyone uprate a service fuse: that fuse belongs to the network operator and only they may change it.
Can I fix it myself?
You can gather the facts that make the survey quick. Look at the cutout beside your meter — the fuse carrier is usually marked 60, 80 or 100. Note whether cooking and hot water are electric or gas, whether there is an electric shower, and whether a heat pump or a second charge point already exists. If you do not know who your network operator is, call 105 and they will tell you. Do not open the cutout, remove the carrier or disturb the meter tails; the cutout is sealed and it is the network's equipment.
When should you call an EV charger installer?
Call an EV charge point installer before you order the unit. They carry out the maximum demand assessment and design around it, and they are the ones who notify the network operator, which is required for a charge point installation and is how load-managed connections are recorded. If the answer is a supply upgrade, they will tell you what the network operator needs from you to quote it.
What will the EV charger installer actually do?
- Read the service cutout rating and assess the property's maximum demand against it
- Check the meter tails, main switch and consumer unit have the capacity for another 32A circuit
- Specify load management with a current sensor on the incoming supply where headroom is tight
- Configure the charge point's maximum output to match what the supply can actually carry
- Notify the distribution network operator of the installation, including any load-managed arrangement
- Advise on a supply upgrade application where limiting the charge point is not acceptable to you
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