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Installation of a 7.4kW MyEnergi Zappi electric vehicle charge point at a property in Probus, complete with intelligent load monitoring technology and upgraded consumer unit to meet current electrical regulations.
The shift towards electric vehicles has created a growing demand for reliable home charging solutions across Cornwall, and this Probus installation demonstrates how modern EV infrastructure can be integrated safely into existing electrical systems. The project centred around installing a 7.4kW tethered MyEnergi Zappi charge point, whilst simultaneously addressing the broader electrical requirements needed to support this technology.
The charge point was mounted on the reveal wall at the front of an outbuilding entrance, providing convenient access for the vehicle owner whilst keeping the installation neat and weather-protected. Choosing a tethered unit meant the charging cable remains permanently attached to the charge point, removing the need for users to store or handle a separate cable each time they charge. This fixed cable approach offers practical benefits in terms of convenience and security, as there’s no loose cable that could be damaged or removed.
Powering an EV charge point demands careful consideration of the property’s existing electrical capacity. Unlike standard domestic circuits, an EV charger draws substantial current over extended periods, which can place significant strain on older electrical installations. The electrical supply to the Zappi was routed through a 40A bi-directional circuit breaker installed within the garage sub-main consumer unit. This specific type of protection device allows current to flow in both directions, which becomes relevant when considering future vehicle-to-grid or vehicle-to-home capabilities that some EV systems now support.
A critical aspect of this installation involved preventing the EV charger from overloading the property’s incoming electrical supply. When an electric vehicle charges at full power simultaneously with other high-demand appliances running in the home, the combined load can exceed the capacity of the main supply fuse. To manage this risk, a Harvi load monitoring device was installed within the main incoming meter cupboard. This clever piece of technology continuously monitors the total electrical consumption across the property, communicating wirelessly with the Zappi charge point to modulate its charging rate accordingly.
The Harvi system works by measuring the current flow through the property’s main tails using a clamp sensor. When it detects that household consumption is approaching the supply limit, it signals the charge point to reduce its charging current. Conversely, during periods of lower household demand, the charger can operate at full capacity. This dynamic load management happens automatically in the background, requiring no input from the user whilst protecting the electrical installation from overload conditions that could trip the main fuse or damage equipment.
Alongside the charge point installation, the existing garage consumer unit required replacement. The new 7-way RCBO consumer unit brought the garage installation in line with the current 18th Edition of the wiring regulations. Each circuit in the new board has its own residual current circuit breaker with overcurrent protection, providing both earth fault protection and overload protection on an individual circuit basis. This arrangement offers better fault discrimination than older split-load boards, where a fault on one circuit would potentially affect multiple circuits.
The new consumer unit incorporates an integrated surge protection device, which serves as the first line of defence against voltage spikes and transient overvoltages. These surges can originate from lightning strikes, grid switching operations, or faults in the wider electrical network. Modern electronic equipment, including the sophisticated control systems in EV charge points, contains sensitive components that can be damaged or degraded by such voltage fluctuations. The SPD diverts these dangerous voltage spikes safely to earth before they can travel further into the installation and cause harm.
Installing the new consumer unit involved careful planning of circuit arrangements to accommodate both existing garage circuits and the new EV charger circuit. The protective devices needed to be correctly rated for the cable sizes and load characteristics of each circuit, with particular attention paid to discrimination – the principle that a fault should be cleared by the protective device closest to it, without affecting other circuits. The bi-directional RCBO serving the charge point had to be specifically selected to handle the continuous high current draw that EV charging involves, whilst also providing the required earth fault protection.
The installation work required running new cabling from the consumer unit to the charge point location. The cables were selected to handle the full 7.4kW load with appropriate derating factors applied for installation method and ambient temperature. Proper cable management involved using cleats, glands, and bushes to secure and protect the cables throughout their route, preventing mechanical damage and maintaining the required fire integrity where cables passed through structural elements.
Testing formed a substantial part of the project, as with any electrical installation work. The completed circuits underwent a comprehensive series of tests to verify their safety and compliance with the wiring regulations. These tests included earth fault loop impedance measurements to confirm that protective devices would operate correctly in fault conditions, insulation resistance testing to verify there were no current leakage paths that could cause danger, and polarity checks to confirm all connections were made correctly. The results of these tests were documented in an Electrical Installation Certificate, which provides a permanent record of the installation’s condition at the time of completion.
The certification process also triggered the requirement for Building Control notification, which applies to most electrical installation work in domestic properties. This notification can be handled through registered competent person schemes, providing assurance to the property owner that the work meets regulatory requirements. For EV charge point installations, this documentation becomes particularly important if the property is later sold, as potential buyers increasingly expect to see proper certification for such significant electrical additions.
Beyond the technical installation, the project involved liaising with the Workplace Charging Scheme grant process. This government initiative provides financial support for the installation of electric vehicle charge points at domestic properties, helping to offset the installation costs and encourage the adoption of electric vehicles. The grant application requires specific technical documentation and installer credentials, which need to be coordinated alongside the physical installation work.
The completed installation provides the property owner with a reliable, intelligent charging solution that integrates seamlessly with their home’s electrical system. The load monitoring ensures they can charge their vehicle without worrying about overloading their supply, whilst the upgraded consumer unit and proper circuit protection deliver peace of mind regarding electrical safety. The tethered design offers daily convenience, and the quality of the Zappi unit means they benefit from features like scheduling, solar integration capabilities, and detailed energy monitoring through the MyEnergi app.
