An unmetered electricity supply (UMS) is a connection where the consumption is calculated rather than measured. It is used for low-power, predictable-consumption equipment such as street lighting, traffic signals, CCTV cameras, and telephone kiosks, where fitting a meter would be impractical or uneconomic.
This guide explains how unmetered supplies work in the UK, which equipment qualifies, and what developers and local authorities need to know.
What Qualifies as Unmetered
Unmetered supplies are defined in the Balancing and Settlement Code. To qualify, the equipment typically needs to:
Have a low and relatively predictable consumption (usually under 500W per connection).
Operate on known schedules (daylight control, timer, or continuously).
Be numerous enough that metering each item individually would be disproportionate.
Typical qualifying equipment:
Street lighting (the largest category by volume).
Traffic signals and illuminated signs.
Bollards and feature lighting.
CCTV cameras.
Speed cameras and variable message signs.
Communications cabinets for broadband, telephone, and mobile backhaul.
Certain tram and rail signalling equipment.
Small EV charging posts in specific configurations.
How Billing Works
Instead of a meter, the supply’s consumption is calculated using a charge code. Each piece of equipment is assigned a code that encodes its wattage, hours of operation, and control mode.
The calculations are managed by Unmetered Supplies Operators (UMSOs), who aggregate the charge codes for a local authority or other client and produce monthly consumption figures for billing by the retail supplier.
Accuracy of the charge codes is important. An incorrectly coded piece of equipment either over-bills or under-bills, and systematic errors across thousands of items can amount to serious money.
Connection Design for Unmetered Supplies
Unmetered supplies typically connect at individual points (for example, at the base of each street lamp column) rather than at a single metered point for the whole network. This introduces a design challenge: the supply network needs to reach every piece of equipment efficiently.
For new developments with significant unmetered equipment (street lighting, CCTV), the design is usually integrated into the wider LV network on the site. A feeder pillar is installed to hand off from the main network to the lighting circuit, and columns are connected in a chain along the route.
Adoption
Street lighting and traffic signal networks are typically adopted by the local highway authority after the development is complete. The adoption requirements vary by authority but typically include:
Compliance with the local highway design standard.
Column types and lantern specifications approved in advance.
Testing and certification of circuits.
As-laid drawings for maintenance records.
Developers need to engage with the highway authority early to confirm adoption standards, because retrofitting to meet adoption requirements after installation is expensive.
Installation Considerations
Three points come up repeatedly on unmetered supply installation.
First, column foundations. Lighting columns require concrete foundations sized for the column height and wind loading. Foundation failures are common where the specification was not checked.
Second, cable sizing. Unmetered circuits are often long. Voltage drop needs to be calculated across the full run, not just at the feeder pillar.
Third, control gear. Photocell control, part-night dimming, and CMS (Central Management Systems) need to be specified at design stage. Retrofitting CMS is possible but expensive.
Timeline
Unmetered supplies usually follow the wider utility connection programme. Typical milestones:
Design: part of the broader LV connection design, approximately six to ten weeks.
Civils and cabling: installed alongside the LV distribution on site.
Lamp and column installation: typically late in the build, after the road surface is in.
Energisation: once the LV network is live.
Adoption: after snagging and commissioning, typically four to twelve weeks after energisation.
Cost
Unmetered supply installation costs sit within the wider civils cost for a development. For standalone lighting circuits in public realm projects:
Standard column, cabling and foundation: £1,800 to £3,500 per column.
CCTV post with feeder pillar: £2,500 to £5,000.
Traffic signal junction: £30,000 to £120,000 depending on complexity.
Common Problems
Mis-coded charge codes causing over or under-billing.
Adoption refusal due to non-compliant column specification or inadequate documentation.
Voltage drop issues on long circuits, causing lamps to underperform.
Uncoordinated installation with other utilities, leading to cable strikes or excavation clashes.
Each is avoidable with proper design and early engagement with the adopting authority.
The Bottom Line
Unmetered supplies are a specialist corner of the UK electricity connection world. The technical rules are well-established, the adoption requirements are predictable once you understand the local authority’s expectations, and the billing model is straightforward once the charge codes are set up correctly. Get design input from a specialist early and the whole installation runs smoothly as part of the wider utility programme, which we often deliver alongside infrastructure and transport projects.