Do I need a new fuse board for an EV charger? Looped supplies, earthing and the DNO
Before installation. 6 minute read
Most of an installer's survey is about the supply, not the charger: the main fuse, whether the cable is shared with next door, the earth, and the state of the consumer unit. What each check can turn up, who fixes it and who pays.
A 7kW charger draws around 32 amps and keeps drawing it for hours at a stretch. Before fitting one, an installer works through the supply from the street to your consumer unit. Which? sets the expectation plainly: the installer "should assess the maximum load of your property" (Which?, February 2026).
What the survey can turn up
| Finding | What happens next | Who usually pays |
|---|---|---|
| Maximum demand stays at or under 60A | Install, then notify the network operator within 28 days | Nothing extra |
| Maximum demand would be 60A to 100A | Installer applies to the network operator before fitting | Depends on the operator's answer |
| Main fuse too small | Network operator upgrades it, or the charger gets load limiting | Varies by operator |
| Looped supply | Network operator separates it | Free at several operators |
| PME earth | Extra protection at the charger | Part of the installer's quote |
| Consumer unit with no room | A separate small unit, or a replacement | Added to the installation price |
Maximum demand and the 60 amp line
The Energy Networks Association runs the process every installer follows, called Connect and Notify. Where the maximum demand of the whole property, including the new charger, is 60A per phase or less and the connection is known to be adequate, the charger goes in first and the network operator is told within 28 days. UK Power Networks puts it as "all they need to do is simply notify us of the installation within 28 days", at no cost to you.
Between 60A and 100A, the installer applies before fitting and the operator confirms within 10 working days whether the charger can go on. The ENA says operators "will never refuse a connection", though work may be needed first. Applications now go through the ENA Connect Direct online form, which the installer fills in.
Load limiting. A charger with a current clamp on the incoming supply can turn itself down when the oven, shower and kettle are all on. The ENA allows a Connect and Notify installation where such a device keeps the maximum demand at 60A or less, provided it monitors the whole property and fails safe. This can make a fuse upgrade unnecessary.
The main fuse
The main fuse sits in the sealed cut out where the cable enters the house, and it belongs to the network operator. Your electrician must not open it. Older houses can have a 30A or 60A fuse. UKPN upgrades them to 80A or 100A, offers a free site visit and expects your meter tails and consumer unit to be correctly sized first. SP Energy Networks says its upgrades are free of charge; UKPN and National Grid do not say the same, so ask your own operator before assuming.
Looped supplies
A looped service is one cable from the street feeding two houses. National Grid Electricity Distribution says they are "typically found in semi-detached or terraced houses", and the ENA adds estates built in the 1970s and 1980s and rural areas. A looped supply is one of the cases where the installer has to contact the operator before fitting.
Several operators separate them free. National Grid says the work "will be funded by us", SSEN says it "can unloop your supply free of charge" for a typical household supply, and SP Energy Networks says "nothing will be owed by you or the installer". UKPN says that where a supply is shared with a neighbour "there may be a charge involved".
Waits come from here. SP Energy Networks gives five to ten days for the work at the property, but says a council permit to dig the pavement can delay the start by up to 90 days. SSEN warns the power is usually off for half a day or more.
The earth
Some homes have a PME earth, where the supply's neutral and earth share one conductor. If that conductor breaks in the street, metal parts connected to the earth, including a car on charge, can rise to a dangerous voltage. Regulation 722.411.4.1 of the wiring regulations says a PME earth "shall not be used when charging outdoors unless one of the five methods are used", the IET explains. In practice that means a charger with open PEN protection built in, a separate device that does the same job, or an earth electrode. The IET notes a separate TT earth may not suit every site, because it has to be kept away from buried metalwork.
The consumer unit
An old fuse box is not automatically condemned. Electrical Safety First's best practice guide, revised September 2026, says a consumer unit "need not be replaced simply because it has rewireable fuses, cartridge fuses or older type circuit-breakers". The same guide suggests a replacement with spare capacity where practical, for later additions such as solar or a charger.
What the charger does need is the right protection. The wiring regulations require an RCD of at least Type A on each charging point plus protection against DC fault currents above 6mA, according to BEAMA's guide. That can be a Type B RCD in the consumer unit, or a Type A with DC detection; the IET says this protection is likely to be inside the charger, but the charger's supplier has to confirm it. Any replacement consumer unit in a home must have a non combustible enclosure or sit inside a non combustible cabinet, a rule in force since 1 January 2016.
Paperwork you should end up with
- An Electrical Installation Certificate to BS 7671. The current version is BS 7671:2018+A4:2026, the only version in force from 15 October 2026 according to NICEIC.
- A Building Regulations compliance certificate, because a new circuit is notifiable work under Part P in England. An installer registered with a competent person scheme self certifies, and the certificate should arrive within 30 days.
- Confirmation that the network operator was notified, or its approval if an application was needed.
Put a photo of the cut out and meter in your quote request, alongside the consumer unit. An installer who can see the cut out may spot a small fuse or a shared supply before the visit rather than on the day.
The part nobody controls
When the survey finds a looped supply or a fuse that needs upgrading, the date of your installation stops being the installer's to set. It depends on the network operator's diary and, if the pavement has to be dug, on the council. Book the survey early if you need the charger by a particular date, such as a new car's delivery.
Installers listed for home charger installation carry out these checks as part of the survey, and those under charger repair deal with chargers that trip the RCD after fitting. Get quotes asks how old your fuse box is, so the first replies can flag it.