Electricity for apartments and multi-storey buildings in Karnataka: transformer, load, CEIG

When a building counts as a "complex"

KERC's conditions of supply (clause 9) and its recovery-of-expenditure regulations apply special rules to commercial and residential buildings, complexes and multi-storey (MS) buildings where:

• the requisitioned load is 25 kW or more, or
• the built-up area is more than 500 sq m (about 5,380 sq ft), counting all floors including the cellar.

Then the owner or developer must provide space in the premises free of cost and, at their own cost, the electric line, distribution transformer and associated equipment. The transformer is dedicated to that building. KERC's 2023 amendment kept these thresholds. Buildings shown separately on the plan but attached, or sharing a passage or staircase, are clubbed together.

How the ESCOM assesses load

The ESCOM assesses load for the entire building area on all floors, as per plan or as built, whichever is higher. KERC's recovery-of-expenditure rules, as published on KPTCL's site, set minimum norms by area. Check the current amendment, because the figures have been revised before:

Worked example: 12 flats of about 1,100 sq ft plus common areas, roughly 1,500 sq m built-up in a city corporation, gives 1,500 × 50 W = 75 kW as a floor. The developer's own load list (flats at 3–5 kW each, plus lifts, pumps, STP, common lighting and EV points) is often higher, and the higher figure is used. One real BESCOM NOC published in a RERA filing (November 2024, 110 flats near Sarjapura) sanctioned 423.3 kW (498 kVA), about 3.8 kW per flat including common loads, with a 500 kVA transformer.

Transformer sizing: the transformer is chosen from the requisitioned load at unity diversity, and rounded up to the next standard rating. The regulation's own example is 75 kW ÷ 0.85 PF = 88 kVA, so a 100 kVA transformer. If supply is given from an existing ESCOM transformer, its total load must stay within 75% of capacity.

The sequence, from plan to handover

The detailed steps for HT supply and transformers are in our HT connection and transformer guide. For plotted layouts, see layout electrification and DTC.

Self-execution vs ESCOM execution

Most developers self-execute: they build the 11 kV extension, RMU, transformer centre and LT works themselves, through a licensed contractor of the right class, to the ESCOM's estimate and standard drawings. The rules:

• Supervision charge to the ESCOM of 10% of the estimated cost, excluding employee cost and meter deposits, capped at ₹15 lakh. A 2026 Karnataka High Court ruling said KPTCL could not raise supervision charges beyond the KERC ceiling on its own. KERC's August 2026 draft regulations propose 5% with the same ₹15 lakh cap; that is a proposal until notified.
• Materials to IS specifications; transformer and switchgear of an ESCOM-approved make, with the manufacturer's test reports approved.
• Joint inspection on completion. Defects are rectified, then the lines and transformer are taken over by the ESCOM free of charge for maintenance.
• A one-year guarantee on materials and workmanship from the date of takeover.
• Under KERC's duty-to-supply rules, once self-executed works are ready and statutory approvals are produced, supply is to be given within 15 days of your readiness notice.

Under ESCOM execution, you pay the estimate and the ESCOM does the work. It is less hassle, but it depends on the ESCOM's tender and material cycle, so it is usually slower.

For very large projects, a KERC notification dated 11 January 2023 requires the developer to provide space for, and bear the cost of, a substation where the load exceeds 7,500 kVA.

Electrical Inspectorate (CEIG), lifts and DG sets

• Buildings above 15 m: under the CEA safety regulations of 2023, and as repeated in KERC's conditions of supply, the owner must give the Electrical Inspector at least 30 days' written notice before supply begins. Supply cannot start without written approval. Plan this; it is a common cause of last-minute delay. See CEIG drawing approval and inspection.
• Lifts: under the Karnataka Lifts, Escalators and Passenger Conveyors Act, 2012, you need permission to erect each lift (Form A1) and then an operating licence (Form B1) from the Electrical Inspectorate. Licences have to be renewed.
• Safety on the building side: an isolator for the whole building at the point of supply, not more than 2.75 m above ground; no other service pipes in the power cable ducts; MCCB and ELCB for each flat.
• DG backup: needs its own approval and a changeover that cannot feed back into the ESCOM supply. See DG set approval.
• EV charging: KERC's 2019 amendment requires buildings with a requisitioned load of 250 kW or more and over 5,000 sq m built-up to provide charging points.

Mistakes that delay power for an apartment

• Transformer space left to the end. The architect fills the ground floor with parking, and the transformer room has to be squeezed in later, or the plan revised. Fix the space and the cable route to the road when the plan is drawn.
• Load assessed too low. The developer's load list leaves out lifts, the STP, pumps and EV points, and the ESCOM's assessment comes in higher. The transformer and the cables then have to be upsized during construction.
• Inspectorate notice sent late. For buildings above 15 m, the 30 days' notice to the Electrical Inspector is often sent after the flats are ready. Send it as soon as the installation is complete enough to inspect.
• Construction power not planned. The site runs for two or three years on temporary supply at the LT-7 rate. Size it properly and keep it renewed; see temporary connection for construction.
• No space on the roof plan for solar. Water tanks, lift rooms and dish antennas take the shadow-free area. If the association may add rooftop solar later, reserve the area and a conduit now. See solar for apartments.
• OC delays. Permanent supply to flats depends on the occupancy certificate or a valid exemption. Read electricity connection without an OC before you promise buyers a handover date.

Individual meters or a single point?

For purely residential apartments on LT supply, the ESCOM gives individual meters to each flat, tapped from a common bus bar through a master metering cubicle at the ground floor, plus meters for the common areas. The building also gets a bulk check meter for energy audit. Individual meters are what buyers expect, and they are what Gruha Jyothi needs.

A single point (bulk) supply with sub-meters run by the builder or the residents' association is also allowed. The association collects on a no-profit-no-loss basis, and this is not treated as resale. The central Electricity (Rights of Consumers) Amendment Rules, 2024 add that if more than 50% of owners vote for individual connections in a transparent ballot, the ESCOM must provide them. Under single-point supply, what the association charges a flat must not exceed the LT domestic tariff, and its total billing must not exceed what it pays the ESCOM.

Shops on the ground floor: a building with shops and flats is assessed on its total requisitioned load, and each shop gets its own commercial meter from the same bus bar. Under the conditions of supply, residential-plus-commercial buildings with a combined requisitioned load below 100 kW are given LT supply with individual meters, each billed at its own tariff. Above that, HT supply with sub-meters for the commercial portion is the usual route. Decide this at the design stage, because it changes the transformer, the metering cubicle and the cable sizes.

Handover: the connections usually start in the developer's name. Flats are transferred to buyers by name transfer once sale deeds are registered, and the common meters go to the association. Transfer the common-area meters before the developer leaves. Unpaid common bills follow the premises, and the new association inherits them. See electricity name transfer.

Questions

Sources

Rules and figures in this article were checked against these sources on 30 Sep 2026. Schemes and tariffs change, so confirm with the official office before you act.

• KERC Conditions of Supply (clause 9) and Recovery of Expenditure Regulations (GESCOM copy)
• KPTCL: KERC Recovery of Expenditure regulations as amended (load per sq m norms)
• BESCOM NOC for a 110-unit residential apartment, Nov 2024 (RERA filing)
• SCC Online: Electricity (Rights of Consumers) Amendment Rules, 2024
• CEA (Measures relating to Safety and Electric Supply) Regulations, 2023
• Karnataka Lifts, Escalators and Passenger Conveyors Act (PRS)
• Karnataka State Electrical Inspectorate: lifts
• Bar & Bench: KPTCL can't hike supervision charges on its own: Karnataka High Court
• SolarQuarter: KERC draft unified Electricity Supply Regulations 2026
• Mercom: KERC guidelines for EV charging points in buildings

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