Senior Primary Design Engineer

Location: Ruislip | Contract Type: Permanent | Working Pattern: Full-Time | Office & Site Based Pay / Benefits: Remuneration for this role is benchmarked competitively within our sector. The Opportunity We are seeking an experienced Senior Electrical Design Engineer (Primary) to take technical ownership of safety-critical primary plant designs for HV and EHV electricity network infrastructure projects across the UK.

Working within a regulated Distribution Network Operator (DNO) environment, you will lead the development, review and assurance of compliant, safe and cost-effective primary electrical designs. Working closely with the Design Manager and multidisciplinary engineering teams, you will oversee primary design delivery from feasibility through to detailed design, coordinating with civil, protection and control, earthing and cable engineering disciplines.

You will also act as a key technical interface with DNO design authorities, clients and construction teams, supporting technical approvals and successful project delivery. With projects spanning 11kV to 132kV, including new substations, refurbishments and network reinforcements, this is an excellent opportunity for a technically strong engineer to lead complex designs, influence engineering standards and provide technical guidance to the wider team.

Lead the development, review and assurance of HV and EHV primary electrical designs, ensuring compliance with DNO standards, ENA specifications, BS EN / IEC standards and industry best practice. Take technical ownership of primary layouts, single-line diagrams, general arrangements, equipment schedules and interface drawings.

Deliver safe, compliant and buildable designs, applying safety-by-design principles and addressing operational, maintenance and fault-condition requirements. Undertake and review primary design assessments, including fault levels, equipment ratings, insulation coordination, electrical clearances and system configuration.

Liaise with DNO design authorities, clients and project teams to secure technical approvals, respond to design comments and support design submissions and departures. Coordinate with civil, protection and control, earthing and cable engineering teams to ensure designs are fully integrated across all disciplines. Provide technical support during procurement and construction, including reviewing manufacturer information, resolving technical queries and attending site when required.

Maintain technical governance and compliance with statutory regulations, DNO specifications and CDM requirements, while contributing to continuous improvement and mentoring less experienced engineers. Essential Skills Degree qualified in Electrical Engineering or a related discipline, with Chartered Engineer (CEng) status or actively working towards chartership.

Significant experience delivering HV and EHV primary electrical designs for UK electricity network projects, ideally within a DNO environment. Strong technical knowledge of primary plant design, including GIS and AIS switchgear, power transformers, circuit breakers, disconnectors, busbar systems, equipment ratings, clearances and insulation coordination.

Proven ability to produce and review primary layouts, single-line diagrams, design reports and technical schedules, with a strong understanding of ENA, BS EN, IEC and DNO-specific standards. Excellent technical communication and stakeholder management skills, with a safety-first mindset and the ability to take ownership of complex designs, coordinate multidisciplinary teams and manage competing project priorities.

Desirable Skills Experience delivering substation new-build, refurbishment and network reinforcement projects across 11kV to 132kV. Knowledge of primary design system studies, including load flow, fault level assessments and operational flexibility. Experience engaging with DNO design authorities, securing technical approvals, managing design departures and supporting client design reviews.

Strong understanding of UK electrical safety legislation, CDM requirements and safety-by-design principles. Experience supporting procurement and construction activities, reviewing manufacturer documentation, resolving site design issues and mentoring junior engineers.

What we offer

At OCU, we believe that meaningful work should come with meaningful support. That's the principle behind Careers with Purpose, our commitment to ensuring every person at OCU feels supported, developed, and valued, not just in their role today, but throughout their career with us. Alongside the opportunity to work on some of the UK's most significant infrastructure projects, we offer a benefits package that we are continuing to develop as we grow, and the kind of career acceleration that only comes from being inside a business moving at this pace.

As a rapidly growing organisation, there are genuine opportunities to progress, broaden your experience, and build a long-term career within OCU Group. For a confidential conversation about this opportunity, please contact Nicola Brooke at Nicola.Brooke@ocugroup.com. Our vacancies are typically advertised for two weeks; however, we reserve the right to close applications early should we receive a sufficient number of suitable candidates.

We therefore encourage early applications. About OCU Group At OCU Group, we don’t just deliver infrastructure - we help power modern life. As one of the UK’s fastest-growing utility and infrastructure businesses, we deliver complex, nationally critical projects across power, energy transition, water, telecoms, and digital infrastructure.

Over the last five years, OCU has grown five-fold to a £1.1bn organisation, expanding both organically and through strategic acquisitions across the UK, Australia, New Zealand and India. Our growth is driven by ambitious people, operational excellence, and a commitment to doing things properly. We work on projects that genuinely matter by supporting the UK’s energy transition, strengthening essential infrastructure, and helping build more sustainable communities for the future.

Whether you’re an experienced professional looking to take ownership of major projects and influence delivery at scale, or someone starting your career through an apprenticeship, graduate programme, or placement route, OCU offers real opportunity to grow, develop, and make an impact. We are building a business where high performance, collaboration, innovation, and accountability sit at the centre of our culture.

Our people are trusted to lead, encouraged to challenge thinking, and supported to continuously develop their skills and careers. At OCU, you won’t just join a growing business, you’ll help shape it. Our Culture & Values At OCU, our values are at the heart of everything we do. We care about safety, lead with integrity, strive to be better every day, make a positive impact, and deliver to grow, together, as One Company United.

Our Commitment to Inclusion At OCU Group, we believe diversity, inclusion, and belonging are fundamental to building stronger teams, better ideas, and a more successful business. We welcome applications from people of all backgrounds and are committed to creating an environment where everyone feels valued and supported.

As part of our commitment to fairness and equality, candidates may be asked to complete an equal opportunities monitoring form during the recruitment process. This information is used for monitoring purposes only and plays no part in hiring decisions. We are proud to be a Disability Confident employer and are committed to offering interviews to candidates with disabilities or long-term health conditions who meet the essential criteria for the role.