What is an on-site substation?
An on-site substation contains equipment for switching, protection and often transforming the electricity supplied to your premises. Its location does not establish ownership [S1]. HSE's specialist switchgear guide covers equipment above 1 kV [S2]. Confirm the asset boundary and maintenance responsibilities before assessing additional charging demand with your electrical engineer. Checked October 2026.
What does an on-site substation mean for your site?
An on-site substation is an installation containing switching, protection and often transformer equipment serving your premises. The transformer changes voltage; switchgear controls and protects electrical circuits [S2].
For your site, its significance is the boundary between the network supply and equipment you must manage. A substation within your boundary is not automatically yours: UK Power Networks describes its own equipment on private land and inside buildings [S1].
Who owns and maintains the equipment?
Check the connection agreement, asset schedule and single-line electrical diagram. A customer substation includes equipment owned by the customer, while a network substation may serve premises under land and access rights. UK Power Networks describes leases or freehold interests with associated access and cable rights for its substations [S1]. Have your solicitor check those documents where property rights are involved.
For equipment you control, request a named maintenance organisation and current records. HSE’s specialist guide covers switchgear above 1 kilovolt (kV), a measure of voltage, and explains maintenance and operational safety arrangements [S2]. This needs relevant engineering competence.
Does a substation mean you can add more chargers?
No automatic capacity follows from its presence. Government guidance asks businesses to assess connection needs against charging power, timing and existing consumption [S3]. A site receiving a higher-voltage supply may use its own transformer; establish your actual arrangement before specifying extra load.
Request the measured demand, equipment ratings and agreed import limit together. Read when a site needs a new substation, supply capacity checks and single-phase versus three-phase supplies for the related basics.
Next step
Prepare your records for the site check and use the charging cost tool, then get matched with an installer that covers your area.
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Common questions
Is a transformer the whole substation?
No. Substation arrangements also include switching and protection equipment; HSE illustrates switchgear layouts [S2].
Can a network operator own equipment inside your building?
Yes. UK Power Networks describes substations on customers' land or within their buildings [S1].
Can you block access outside opening hours?
UK Power Networks requires unrestricted access to its substations at all times; check your access agreement [S1].
Does switchgear need routine inspection and maintenance?
Yes. HSE describes inspection, testing, maintenance planning and records for owners and users [S2].
Is distance to existing equipment the only connection-cost driver?
No. Government guidance also identifies the required connection size as a cost factor [S3].
Ask about your site
Sources
- Electricity equipment on your land, UK Power Networks,Last checked 19 October 2026
- Keeping electrical switchgear safe, Health and Safety Executive,Last checked 19 October 2026
- Connecting electric vehicle chargepoints to the electricity network, Office for Zero Emission Vehicles,Last checked 19 October 2026