What is maximum import capacity for a business site?

Maximum import capacity is the electricity import limit agreed for your connection, measured in kVA. Maximum demand describes the highest measured demand over the relevant period, rather than that agreed limit. National Grid Electricity Distribution calculates exceeded capacity using half-hourly data [S3]. An assumed 100 kVA agreement is capacity reserved, not consumption of 100 kWh. Checked October 2026.

Last checked 18 October 2026

What does maximum import capacity mean?

Maximum import capacity, or MIC, is your agreed connection limit for drawing power from the network. National Grid Electricity Distribution records it in kilovolt-amperes, or kVA, within the connection agreement where applicable [S1]. Your paperwork may describe the agreed limit as agreed supply capacity or authorised supply capacity; ask the network to confirm which value applies to your connection.

Your distribution network operator, or DNO, runs that local network. It is the organisation to involve when changing the agreed capacity. The limit concerns power available at a time, rather than the total electricity used during a month. For the full billing explanation, read agreed supply capacity charges.

How does it differ from maximum demand and kWh?

Maximum demand is the highest measured demand for the relevant reporting window. The East Midlands charging statement calculates demand exceeded capacity for every half-hour and applies the maximum from the billing period [S3]. The agreed capacity is the contractual reference against which demand is assessed.

A kilowatt, or kW, measures active power; a kilowatt-hour, or kWh, measures energy. The network’s charging statement distinguishes active energy from apparent demand in its calculation [S3]. Do not compare a kWh consumption total directly with a kVA limit. Read kVA, kW and power factor before converting measurements for a capacity assessment.

Where should you look on the bill?

Start with your connection agreement. The network says MIC may also appear in your electricity supply contract [S1]. If it is unclear on the bill, ask for the capacity used in billing and the applicable charging basis. Capacity charges may appear under Distribution Use of System, or DUoS [S2].

For a purely assumed illustration, not a quote, take an agreed capacity of 100 kVA, a capacity charge of £0.10 per kVA per day and a 30-day billing period. The capacity element is 100 × £0.10 × 30 = £300, before other charges and tax. A lower measured demand does not itself change the assumed contracted quantity. This is bill arithmetic, rather than a published rate or a forecast saving.

Use business electricity price data for context, then obtain the actual charge schedule for your site. The half-hourly metering guide covers the shared metering and DUoS basics.

Keep residual fixed charges separate: a change to MIC does not automatically change the residual charging band [S4]. Ask for each affected line to be identified before estimating a financial effect.

How can new equipment affect charges?

Check the combined site demand before adding chargers, machinery or battery charging. For applicable tariffs, the East Midlands statement includes charges for capacity exceeding the agreed limit [S3]. Ask your designer to test coincident loads and controls, including busy operating periods, rather than relying on annual energy alone.

If you are considering a lower limit, keep future needs in the assessment. National Grid Electricity Distribution warns that reducing capacity releases it back to the network [S2]. Ask for the proposed agreement and bill impact in writing. For contractual interpretation, check with your solicitor.

What should you do next?

Bring your bill, connection agreement and demand records to the site-power tool. Continue through the cut energy costs hub and site check, then get matched with an installer that covers your area.

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