EV charger on a looped supply: what installers need to know

A looped supply is one of the most common reasons a straightforward EV charger job stalls. This guide explains what a looped service is, why it matters for a charger, who decides what happens next, and what the customer can do in the meantime.

What a looped supply is

In a looped (or shared) service, two or more properties are fed from one service cable from the street, instead of each having its own. It's common in older terraced and semi-detached housing. Sometimes each property has its own cut-out on the shared cable, and sometimes a cable runs from one property's cut-out to feed next door.

Signs that a supply may be looped include two service cables at the cut-out, or a cable leaving the cut-out towards the neighbouring property. Photos help, but they don't settle it. Only the distribution network operator (DNO) can confirm whether a supply is looped. Never open or tamper with the sealed cut-out.

Why it matters for an EV charger

A shared service cable was sized for ordinary household loads across all the properties on it. A 7 kW charger adds up to 32 A for hours at a time, usually overnight, when the neighbours may be charging or heating too. The DNO needs to know that the shared cable and fuses can carry that.

For that reason, a looped service usually takes a charger out of the ENA's "connect and notify" route (fit first, then notify the DNO within 28 days). Expect to apply to the DNO first and wait for their answer.

Unlooping: cost and timelines

If the DNO decides the supply needs unlooping, they run a new, separate service cable to the property. For low-carbon technology like EV chargers and heat pumps, DNOs usually do this at no charge to the customer, but check with the DNO for the specific job.

Timelines vary a lot. A simple unloop can take a few weeks. It can take many months where the work needs access to a neighbour's land, crosses a private road or driveway, or needs a wayleave. It's worth the customer talking to their neighbours early, so access isn't a surprise if the DNO needs it.

Can a charger go in before the unloop?

Sometimes. Some DNOs will accept a load-managed charger before the unloop is finished, and others insist on unlooping first. It's the DNO's decision, so ask them directly and get the answer in writing.

With load management, a current clamp on the property's meter tails makes the charger turn itself down so the whole property stays under a limit the DNO agrees. The clamp only sees that one property, not the neighbours on the loop, which is why the DNO decides whether a limit on one side is enough for the shared cable. If the DNO accepts it, expect them to set the limit, and to want the charger to drop to a safe level if it loses the clamp signal. EREC G100 sets out these requirements for customer load management schemes.

A useful one-line question to the DNO is: "Will you accept a load-managed charger limited to [X] A before the unloop, and if not, roughly how long will the unloop take?"

Charging while the customer waits

A granny lead on a 13 A socket draws around 10 A, which is a normal household-sized load. DNOs don't usually ask to be notified about a plain socket in the way they do for a wallbox. A socket installed for charging a car still counts as EV charging equipment under Section 722 of BS 7671. That means a dedicated circuit, suitable RCD protection, an outdoor-rated socket and, on a PME supply, the extra earthing measures for charging outdoors. It's notifiable work and should be certified.

A 32 A commando socket isn't a way round the loop question. At 32 A it's the same 7 kW load as a wallbox, usually without load management, so it needs the same DNO notification and Section 722 protection.

What Gridcap can and can't tell you

Gridcap checks the headroom on the incoming supply, phase by phase, from the main fuse rating and the property's peak demand, with and without G100 load management. It can't tell whether a service is looped, and it doesn't assess the shared cable or your neighbours' load. If you suspect a loop, get the DNO's answer on that first. A Gridcap report can then support the application with the property's own figures, but the DNO still makes its own assessment.

Installer checklist

1. Check for signs of a looped service at the survey, and photograph the cut-out without opening it.
2. Ask the DNO to confirm whether the supply is looped and what the main fuse rating is.
3. If it's looped, apply to the DNO before installing, and ask whether a load-managed charger is acceptable before any unloop, and at what limit.
4. If unlooping is needed, ask for a rough programme, and suggest the customer speaks to their neighbours early.
5. If the customer needs to charge in the meantime, install and certify a dedicated socket to Section 722.