HV Substation Services | Installation & Fit-Out | R&D Cable Jointing Ltd
Based in Kent — Working Nationwide
HV Substation Installation & Fit-Out

HV Substation Services

R&D Cable Jointing provides full HV substation installation and fit-out services for 11kV and 33kV networks. From earthing and small power through to LV STC panels, CT wiring and connection day management.

R&D Cable Jointing delivers turnkey substation solutions for DNOs, private networks and EV infrastructure across the UK. Whether it's a GRP or full brick-built fit-out, we handle every aspect of the installation from civil handover through to DNO adoption and energisation — with precision, compliance and a clean finish.

Complete Substation Installation Scope

We provide one contractor for the full HV and LV substation scope — reducing handover complexity, keeping accountability clear and simplifying programme management for the principal contractor or ICP.

  • 11kV substation installations — new build GRP and brick-built substations from civil handover to energisation
  • Complete internal fit-outs — SP&L, RTUs, CT metering, panels and wiring
  • Transformer and switchgear landing — positioning, setting and connecting HV equipment into the substation to DNO specification
  • Feeder pillar terminations and connections — LV feeder circuits to DNO and IDNO standard
  • Internal and external substation earthing — to DNO specification
  • Small power and lighting installation — internal substation fit-out
  • LV STC panel installation and commissioning
  • CT and VT wiring for COP3/5 metering box installation
  • Hot site readiness — pre-energisation checks and DNO audit-ready presentation
  • Testing and certification — sheath integrity, insulation resistance and pre-energisation testing
  • DNO/IDNO compliance, audit support and adoption attendance
  • Connection day management — taking control of the LV network on behalf of the IDNO at energisation

Turnkey delivery. We take the substation scope from civil handover through to DNO adoption and energisation. One contractor, clear accountability, no gaps in the programme. Send us the project details and we will confirm availability and a delivery plan.

Specialist Substation Installations

Beyond standard ICP and DNO connection substations, we support a growing range of specialist substation types where the installation requirements differ from a standard secondary substation:

EV Charging Substations

Commercial EV charging hubs — from kerb-side schemes to motorway service area rapid charging installations — require dedicated 11kV substations once the total charger load exceeds what the local LV network can supply. We deliver the full substation scope for EV charging infrastructure, integrating with the charge point operator's programme so the supply is ready when the CPO is on site. See our Commercial EV Charging Infrastructure page for more detail.

Solar and Battery Storage (BESS) Substations

Solar farms and battery energy storage systems require dedicated 11kV or 33kV substations for grid connection. Whether it's a ground-mounted BESS installation in a field or a rooftop solar connection on a commercial building, our approach is the same — systematic, safe and delivered to specification. See our Solar, BESS & Wind HV Jointing technical guide for more detail.

Industrial and Private HV Networks

Private HV networks serving industrial estates, data centres, commercial campuses and large facilities require the same standard of installation as DNO substations — often with tighter programme constraints and the additional complexity of working around live operations. We have experience delivering substation works in live industrial environments and understand the permit and outage coordination requirements.

Working Safely in HV Substation Environments

Substation environments demand strict controls, planning and clear communication. We align with your site safety rules, permits and working systems to deliver work efficiently without disruption to live operations.

  • Permit-to-Work and isolation coordination with the SAP — we can provide SAP in-house up to 33kV
  • Clean cable routing and organised substation fit-out — audit-ready presentation as standard
  • Support during planned outage windows and energisation day
  • Coordination with civils contractors, DNO representatives, ICPs and commissioning teams
  • RAMS aligned to your site rules, CDM requirements and programme

Why Choose R&D Cable Jointing

  • Fully qualified jointers and substation installers — EUSR registered, trained to UKPN standards at Citrus Training
  • Deep understanding of DNO and ICP standards — we know what DNO adoption teams and IDNO auditors are looking for
  • In-house SAP up to 33kV — no need to coordinate a separate SAP contractor
  • Focused on safety, neatness and reliability — audit-ready finishes on every installation
  • One contractor for HV and LV scope — from the cable jointing to the LV STC panel, under one contract
  • From ground prep to final commissioning — we stay engaged until the substation is energised and adopted

Based in Kent, working nationwide. We regularly support substation programmes across London, Kent, Essex, Hertfordshire, Surrey, Suffolk, Cambridgeshire and Bedfordshire — and travel nationally for the right scope. Contact us at info@rdjointing.co.uk or call 0330 043 6689.

Frequently Asked Questions

What areas do you cover?
Based in the South East (Kent), we work nationwide across the UK. We regularly support projects across Essex, London, Kent, Hertfordshire, Surrey, Suffolk, Cambridgeshire and Bedfordshire, and travel further for larger projects.
What voltages can you work with?
LV, 11kV and 33kV. Our SAP authorisations cover up to 33kV for switching, permits and live working supervision.
What types of cable do you joint?
PILC, XLPE, Waveform and other common LV/HV cable types. If you're unsure whether we can handle your cable type, just ask.
Can you handle full substation installations?
Yes. We handle everything from landing, earthing and fit-out through to testing, commissioning, DNO audit attendance and taking control of the LV network on connection day on behalf of the IDNO.
What's the difference between a jointer and a SAP?
A jointer physically installs and connects cables. A Senior Authorised Person (SAP) issues permits and ensures the system is safe to work on. We provide both in-house.
Can you supply materials or work labour-only?
Both. We're happy to supply jointing kits and accessories, or to work with your own supplied materials — whatever suits the job.
How do I get a quote?
Email info@rdjointing.co.uk with your scope, cable type, voltage and location. We'll come back quickly with availability and a clear plan.

Substation installation coming up?

Tell us about the project — cable type, substation spec, DNO/IDNO and programme — and we'll come back with availability.