DG set approval in Karnataka: Inspectorate, changeover switch, CPCB IV+ and KSPCB rules

Which rules apply

Three sets of rules meet at a DG set:

• Electrical safety: the CEA (Measures relating to Safety and Electric Supply) Regulations, 2023, and the Karnataka Electrical Inspectorate (Powers, Functions and Levy of Fees) Rules, 2018, last amended in January 2025. These cover drawing approval, inspection, earthing and protection.
• Emission and noise: central norms under the Environment (Protection) Rules, enforced by CPCB. New diesel gensets up to 800 kW must meet CPCB IV+ from July 2023.
• State pollution control: the Karnataka State Pollution Control Board (KSPCB), which has ordered emission control devices on sets of 125 kVA and above.

When the Electrical Inspectorate is involved

Regulation 34 of the CEA 2023 regulations leaves it to each State to notify the generating capacity above which a set must be inspected by the Electrical Inspector before commissioning. Regulation 45 says installations above the State's notified voltage, and generating units above that capacity, must be inspected and approved before supply starts. Below those limits, the owner self-certifies and sends the report to the Inspector.

In Karnataka, DG set installations are submitted to the jurisdictional Electrical Inspectorate office for drawing approval and then inspection, along with LT and HT consumer installations and buildings of 15 m and above. The Inspectorate's fee rules, as amended in January 2025, list drawing fees for generating sets starting from the "up to 100 kVA" band, so even modest commercial sets are expected to come in. An approval issued by the Electrical Inspector, Bangalore South in August 2025 for a 125 kVA, 415 V set used on a construction site cites Regulation 32 of the CEA 2023 regulations and was valid for six months.

The changeover switch: non-negotiable

When the grid fails and your generator runs, the generator must be physically disconnected from the ESCOM supply. If it is not, the generator's output flows back through your service cable into the distribution transformer, which steps it up to 11 kV on the line. A lineman who has opened the line at the substation and is working on it can be electrocuted. This is called back-feeding.

• Use a changeover switch (manual) or an automatic transfer switch or AMF panel, rated for the full load current, that breaks one source before making the other. It must switch phase and neutral as per the design.
• For installations above 650 V, Regulation 47 of the CEA 2023 regulations specifically requires supplies not meant to run in parallel to be interlocked so that inadvertent paralleling or back-feed is not possible. On LT, the changeover is what achieves the same thing.
• Never connect a portable generator by a "suicide plug" into a wall socket, and never wire it into the DB without a changeover. Inverter and solar hybrid systems need the same thinking; see our rooftop solar guide.

Earthing and protection

Regulation 43 of the CEA 2023 regulations requires the neutral of every generator to be earthed by not less than two separate and distinct connections, and the frame of every generator above 250 V to be earthed by two separate connections as well. Regulation 47 requires earth fault or leakage protection on all generators of 100 kVA and above.

• Plan dedicated earth pits for the DG neutral and body, tested and recorded before inspection. See the earthing and pre-inspection checklist.
• Size the cable from DG to changeover for the full rating and the run length, and provide an MCCB or ACB on the DG output.
• Keep fuel storage, battery and exhaust away from the panel. Fire extinguishers suitable for electrical and oil fires should be at hand.

CPCB IV+, noise and stack height

New diesel generator sets up to 800 kW sold from July 2023 must meet the CPCB IV+ emission standard, which sharply reduces particulate matter and NOx compared with the older CPCB II sets. Buy only a set with a valid type-approval certificate and the CPCB IV+ marking on its nameplate.

The noise rules require a set to come with an acoustic enclosure, with a sound pressure level not exceeding 75 dB(A) at 1 metre from the enclosure surface and an enclosure insertion loss of at least 25 dB(A). Keep the enclosure doors shut while running and maintain the seals, or the set stops complying.

The exhaust stack height for sets below 1,000 kVA follows the formula H = h + 0.2 × √kVA, where H is total stack height in metres and h is the height of the building where the set is installed. For example, for a 100 kVA set next to a 6 m building: √100 = 10, so H = 6 + 2 = 8 m.

Sizing and placing the set

Most DG problems we are called for are sizing and placement mistakes, not approvals:

• Size for what must run, not the whole sanctioned load. List the essential loads: lifts, pumps, lighting, server, cold room. Add starting current for motors; a borewell or lift motor can draw several times its running current at start. The DG supplier should check the motor starting against the alternator.
• Balance the phases. A three-phase set with all single-phase loads on one phase runs unbalanced and overheats the alternator.
• Ventilation and access. Do not box a set into a basement corner or a closed room without planned air inlet, outlet and exhaust routing. Leave space around the enclosure for maintenance.
• Plinth and drainage. Mount on a level concrete plinth above flood level with anti-vibration mounts, and keep diesel spills away from drains.
• Neighbours. Point the exhaust and the radiator air away from windows and the neighbour's wall. Noise complaints are the most common reason a working set gets stopped.
• Homes with small portable sets. The same back-feed danger applies. Run selected appliances by a proper cable from the set, or have a changeover fitted in the DB by a licensed contractor.

Common mistakes we find at DG installations

• Installed first, approved later. The set is placed and wired, and only then are drawings sent to the Inspectorate. If the layout, earthing or changeover does not meet the regulations, the work is redone. Get the drawing approved before you build the plinth.
• One earth pit for everything. The DG neutral and frame tied to the building's existing earth, or one new pit shared by both. The regulations call for two separate connections for each, and the pits should be tested and recorded.
• Changeover rated below the incomer. A changeover smaller than the supply it switches runs hot and can weld its contacts, which defeats the whole point of break-before-make.
• A set far bigger than the load. Diesel engines run for long hours at very light load build up carbon and unburnt fuel in the exhaust. Size the set to the essential load and starting currents, not to the full sanctioned load.
• Stack cut short. The exhaust pipe stops at the roof edge to save cost or for looks, below the height the formula requires, and smoke enters the floors above.
• No log book. Keep a record of running hours, fuel, servicing and test results. It helps at inspection, at KSPCB checks and when a fault has to be traced.

In apartments, the DG usually backs up lifts, pumps and common lighting, and the lift is often the load that decides the size; see power for apartments and multi-storey buildings. Factories should plan the DG together with the main connection; our industrial connection guide for MSMEs covers that process.

KSPCB consent and emission control devices

On 25 May 2023 the KSPCB issued a notification requiring DG sets of 125 kVA and above across Karnataka, at industries, buildings, projects and other establishments, to be retrofitted with type-approved emission control devices or moved to gas-based generation, within six months. Non-compliance can lead to action under the Air Act, 1981. An earlier 2021 order on the same subject drew criticism because certified devices were not yet available, so check the current position with KSPCB before you buy a device.

Whether you also need separate KSPCB consent depends on the activity of your establishment rather than the DG set alone. A factory that already holds consent should show the DG set in its consent application; apartments and commercial buildings should ask the regional KSPCB office.

Documents and steps

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.

• CEA (Measures relating to Safety and Electric Supply) Regulations, 2023 - Gazette
• Karnataka Electrical Inspectorates (Powers, Functions and Levy of Fees) (Amendment) Rules, 2025
• Electrical Inspectorate - Approval of drawings
• Sample DG approval, Electrical Inspector Bangalore South (Aug 2025)
• CPCB IV+ emission norms and gensets (Jakson)
• CPCB system and procedure for compliance with noise limits for gensets
• Diesel generator sets: stack height (HSPCB environmental standards)
• KSPCB notification on retrofitting emission control devices to DG sets 125 kVA and above (TeamLease RegTech)
• Karnataka mandates retrofitting of diesel generators (Citizen Matters, Nov 2021)

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