11 kV Substation for a Factory: Components, Cost Drivers and the Approval Sequence

An 11 kV factory substation is the incoming HT switchgear, DISCOM metering, transformers, LT panels and earthing, built to the DISCOM's metering rules and the Electrical Inspector's approval. Its cost depends on transformer rating and type, breaker panel count, protection and metering scheme, civil works and cable lengths, not kVA alone, so price it only after the single-line diagram is frozen.

What is inside a factory substation?

The same eight blocks appear in almost every 11 kV scheme, and each one has its own cost driver. Ask any contractor to price them as separate lines, because a single lump sum hides what moved.

Two items sit outside the contractor's price. The DISCOM's own charges for the connection, line and bay are set by the state supply code and paid to the DISCOM. Testing and inspection fees depend on the state. Keep both in the project budget, separate from the substation contract.

What decides the size and the voltage?

The substation follows your contract demand, and the state supply code decides the voltage at which that demand is served. Under the Punjab State Electricity Regulatory Commission's 2024 Supply Code, Regulation 5(2) specifies 11 kV for large-supply industrial demand up to 5,000 kVA, with 33/66 kV above that up to 20 MVA. Haryana's code, as reproduced in the DHBVN compendium, specifies 11 kV for contracted load above 50 kW and up to 5,000 kVA, and 33 kV for loads above 2,000 kVA and up to 25,000 kVA. Other states, including Uttar Pradesh, publish their own bands in their supply codes. These bands overlap or move with amendments, so confirm with your DISCOM which applies; our note on LT versus HT connections covers the lower end.

Within an 11 kV scheme, transformer sizing follows the load list, the diversity you can justify, motor starting and growth. Undersized transformers are a common growth bottleneck (see why substations get undersized), while oversized ones waste no-load loss and capital. The transformer sizing calculator gives a first kVA from connected load and demand factor, and a second transformer or space for one is far cheaper to plan than to retrofit. Fault level matters too: a larger or additional transformer raises the fault level that breakers, busbars and cables must withstand.

Cost drivers, without a price

We do not quote a rupee figure for a substation, because any such figure would be wrong for your site. These are the drivers, roughly in the order they surprise owners:

• Transformer losses and type. Ask for guaranteed no-load and load losses. A cheaper transformer with higher losses costs more over years of running.
• Panel count. Every outgoing feeder and every future spare way is a panel. Decide the single-line diagram before you price.
• Metering and protection specification. The DISCOM's required meter class, CT and PT arrangement, and any telemetry can add or remove cubicles.
• Site conditions. Soil resistivity drives the earthing design, and long cable routes, rock, high water table or crane access add civil and installation cost.
• Layout. An outdoor yard, an indoor room and a packaged unit differ in civil cost, fire separation and inspection steps.
• DG and solar interfaces. Changeover or synchronisation with a DG set, and any solar export, add protection and panel scope. See our notes on connecting solar at 11 kV and solar with DG sets.
• Testing and commissioning. Relay testing, insulation and earth resistance tests, and the inspection visit are part of the price; make sure they are in it.

The approval sequence

The order matters, because each step depends on the previous one. A typical sequence is:

1. Load assessment and single-line diagram. The foundation for every later document.
2. DISCOM application and feasibility. The DISCOM confirms the supply point, voltage and charges. Under Punjab's 2024 code, the demand notice is due within 10 days of receipt of the application for supply at 11 kV; read the regulation for the other time limits.
3. Drawing approval where your state requires it. Some Electrical Inspectorates review substation drawings before construction. Ask early.
4. Construction and testing. Build to the approved drawing and test before you ask for inspection.
5. Electrical Inspector approval. Under regulation 45(6) of the CEA (Measures relating to Safety and Electric Supply) Regulations, 2023, an owner who adds to or alters an installation must not connect the additions to supply until they are approved in writing by the Electrical Inspector or self-certified, depending on the voltage your state has notified. In West Bengal, WBSEDCL's guidelines say its commercial clearance for 11 kV and above follows the Inspector's approval.
6. Meter sealing and energisation. The DISCOM seals the meter and releases supply.
7. Safety officer. Regulation 5(3) requires a factory with more than 250 kW connected load to designate an Electrical Safety Officer.

Our CEIG approval guide and notes on HT connection delays explain where files usually stall: inconsistent drawings, missing test certificates, or a load figure that differs between the DISCOM application and the inspection file.

How Secured Engineers helps

We design substations in-house and file CEIG and DISCOM applications in-house, so the single-line diagram, the DISCOM file and the inspection file come from the same set of drawings. HT and LT electrical work can sit under one contract with the rest of the MEPF scope and solar, from our Noida (Delhi NCR) and Ludhiana offices. The company has delivered 535+ projects across 18+ states, with 89.77% repeat clients. We also review another contractor's single-line diagram, panel schedule and quotation before you order.

The electrical infrastructure page describes the scope. To have your file reviewed, send the load list, single-line diagram and any DISCOM estimate on WhatsApp, call +91 70099 85817, or ask for a free proposal that starts with a review of your file.