What is maximum demand on your electricity supply?
Maximum demand is the highest measured average power over a stated interval and reporting period. For half-hourly data, an assumed 20 kWh in 0.5 hours equals 40 kW average demand. Network capacity calculations also account for reactive energy [S1]. Compare like units before assessing space for chargers; measured demand is separate from your agreed import limit [S2]. Checked October 2026.
What does maximum demand mean for your site?
Maximum demand is the highest measured average electrical power within a defined interval over a stated reporting period. In half-hourly network billing, active and reactive energy records feed the capacity calculation [S1].
Why it matters for your site: the peak helps your designer assess whether new chargers could run alongside your existing operations. It is evidence of past use, rather than permission to draw more electricity.
Keep it separate from maximum import capacity: the limit agreed for your connection. UK Power Networks expresses that limit in kilovolt-amperes (kVA) [S2].
How do half-hourly readings become a demand figure?
A kilowatt (kW) measures active power; a kilowatt-hour (kWh) measures energy. For an assumed half-hour reading of 20 kWh, average active demand = 20 ÷ 0.5 = 40 kW. Repeat for each interval and find the highest result over your chosen period. This is an illustration, not a site measurement.
That average does not describe every brief peak inside the interval. Nor does doubling kWh give kVA: the network calculation includes reactive energy [S1]. Use kVA, kW and power factor for the distinction.
What should you check before adding chargers?
Request interval data with units, timestamps and actual or estimated flags. Mark shutdowns and changes in trading hours. Ask your designer to assess proposed charging against the building’s concurrent demand, rather than simply subtracting unrelated headline ratings.
Read half-hourly metering and network charges alongside the business electricity data. In the East Midlands statement, exceeded capacity is assessed for every half-hour and the billing-period maximum is applied [S1]. Your distribution network operator (DNO) runs the local network; confirm its own charging statement and your contract.
Next step
Explore cutting energy costs with your records in the site-power tool, then get matched with an installer that covers your area.
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Common questions
Is connected load the same as recorded demand?
Equipment ratings describe possible loads. The network's exceeded-capacity calculation instead uses measured half-hourly active and reactive energy. Request the interval records before comparing the two [S1].
What happens if demand exceeds the agreed capacity?
The East Midlands statement applies an exceeded-capacity charge to the excess for the billing period. Check your network's applicable tariff rather than assuming a universal penalty rate [S1].
Does a lower peak automatically reduce the import agreement?
No. UK Power Networks describes reducing maximum import capacity as a change to the agreed connection. Request confirmation of any amendment separately from your measured demand report [S2].
Can a kW figure be compared directly with a kVA limit?
Keep them separate. The network's apparent-demand calculation includes reactive energy as well as active import. Ask for the corresponding kVA figure or the relevant power factor [S1].
Can capacity released now always be recovered later?
No. The East Midlands statement warns that restoring reduced capacity may need reinforcement and associated charges. Include planned equipment before requesting a reduction [S1].
Ask about your site
Sources
- East Midlands use of system charging statement effective April 2026, National Grid Electricity Distribution,Last checked 19 October 2026
- Reduce your electricity supply, UK Power Networks,Last checked 19 October 2026