In short. Government buildings, emergency response operations and remote installations share one requirement: the generator must work on the day it is needed after months of idleness, and the paperwork must show it. Classify loads by public-service consequence rather than backing up the whole building, specify fuel autonomy in days where access is uncertain, insist on tested AMF transfer and remote monitoring, and document the installation to the standard a tender, audit or disaster review will demand.
Three different missions under one heading
A district collectorate, a flood relief camp and a forest check post have little in common except that each depends on a diesel generator and none has a plant engineer on site. Government and public buildings, such as offices, courts, police stations, fire stations and municipal facilities, usually have grid supply and need standby power for defined public-service functions. Emergency operations, such as disaster relief, cyclone shelters on the Andhra coast, field hospitals and election infrastructure, need power mobilised quickly to a site that had none, for an unknown period. Remote installations, such as telecom repeaters, border posts, tribal welfare facilities and irrigation lift schemes, need power where the grid is weak or absent and service visits are infrequent and expensive. The industry overview places these alongside the commercial and industrial sectors.
| Mission | Typical duty | Key design driver | Usual arrangement |
|---|---|---|---|
| Government and public buildings | Standby, under 200 hours a year | Starting reliability after long idle periods | Fixed set with AMF, UPS on records and IT, weekly test run |
| Emergency and disaster response | Prime for days or weeks | Speed of mobilisation and fuel supply | Mobile or containerised sets with temporary distribution |
| Remote installations | Prime or continuous, often with solar | Service distance and fuel logistics | Paired small sets or diesel-solar-battery hybrid with remote monitoring |
Classifying public-service loads
The temptation in a government tender is to specify a generator for the building’s full connected load. The result is a set three or four times larger than the essential load, which runs at 15 per cent load during outages, costs more to maintain and fails the low-load test of reliability. A better specification starts by asking which functions the public depends on during an outage. At a police station it is communication, lighting, custody areas and CCTV. At a fire station it is the bay doors, communication and the compressor for breathing apparatus. At a district office it is the records room, the server room, public counters and lifts for accessibility. At a school or hostel it is lighting, water pumps and the kitchen; comfort air conditioning in general offices is almost always shed. The load classification guide describes how to record the classification so that the tender, the generator sizing and the test plan all refer to the same list.
Fuel autonomy and starting reliability
A government generator may sit unused for months and then be asked to run through a 36-hour cyclone outage. Starting reliability comes first: batteries on a float charger with a monthly capacity check, a weekly automatic test run logged by the controller, and a fuel system kept free of water and microbial growth. Fuel autonomy comes second, and it should be stated in hours of running at the expected load, not in tank litres.
Autonomy (hours) = Usable tank volume (litres) ÷ Consumption at expected load (litres per hour)
Diesel generator calculator
Fuel use, runtime, tank size and cost
How this is calculated
Real power is kVA × power factor. Fuel use is estimated as L/h ≈ 0.04 × rated kW + 0.22 × load kW, which follows the usual shape of modern diesel gensets: about 0.26 L per kWh near full load, rising towards 0.38 L per kWh at a quarter load because the engine's fixed losses are spread over less output.
If you enter the full-load figure from your engine datasheet, the curve is scaled to match it. Runtime is usable fuel ÷ L/h. Tank size is L/h × hours, plus the reserve margin, divided by the usable fraction.
These are planning estimates, typically within 10 to 15 percent of a healthy engine. Actual use depends on the engine model, its condition, altitude, ambient temperature and how the load varies. For a figure you can rely on, use the manufacturer's fuel curve or a metered test.
Estimates only, worked out in your browser. For a checked selection, send us your load list and site details or call 098852 01608.
Usable volume is the tank capacity less the unusable portion below the suction and the ullage at the top, typically 85 to 90 per cent of nominal. A 62.5 kVA set carrying a 30 kW essential load consumes roughly 8 to 9 litres an hour, so a 990-litre base tank with 850 usable litres gives about four days of continuous running (illustrative). For a remote site with monthly fuel deliveries the same arithmetic points to bulk storage of several thousand litres, and above the Petroleum Rules exemption a PESO licence is needed. The fuel runtime guide works through the calculation.
Emergency mobilisation
Disaster power is logistics first and electrical engineering second, but both must be present. The equipment that moves fastest is a trailer or skid-mounted set between 30 and 250 kVA, a temporary distribution board with residual current protection, a drum of flexible armoured cable and a fuel bowser. What cannot be improvised on arrival is the earthing, the connection to an existing switchboard, and the decision about which circuits to feed. A relief shelter or field hospital should have a pre-planned connection point and a single-line diagram kept with the building, so the arriving crew does not trace circuits in the dark. No supplier should promise a mobilisation time without a contract that defines it, and the authority should plan on stated distances and road conditions rather than assurances. The emergency temporary power page covers what a rapid deployment includes, and the wider rental and temporary power section covers planned work.
Remote sites and hybrid generation
At a remote site the cost of a service visit and the cost of delivered fuel dominate everything else. Two small generators in duty and standby are usually better than one large set, because one can fail without loss of supply until the next visit. Where the site runs through the day, a solar array with battery storage and a generator in a controlled hybrid can cut diesel consumption sharply and allow the engine to run only a few hours a day at good load, which also extends service intervals. Remote monitoring through the controller over a cellular or satellite link lets a service engineer see run hours, alarms and fuel level without travelling, and turns a surprise breakdown into a planned visit. The solar-diesel-battery hybrid page explains how the controller decides which source runs.
Documentation for tenders, audits and handover
Public projects are judged on records. The specification should require, and the supplier should provide, the manufacturer’s test certificate, the CPCB IV+ type approval reference for new sets up to 800 kW, the installation single-line diagram, earth resistance results, the AMF transfer test record with measured transfer time, a load test record at 70 per cent or more of rated load, and an operation and maintenance manual with the service schedule. A maintenance contract should state visit frequency, breakdown response time and the items included; the generator AMC page describes a workable contract. Without these records an installation cannot be defended in an audit, however well it performed.
Common mistakes
- Specifying the generator for the building’s full connected load. The set runs at a fraction of its rating, costs more to buy and maintain, and wet-stacks during long outages.
- Accepting a generator installation without a logged transfer test and load test. The first real outage reveals a dead battery or a wrongly wired AMF panel.
- Stating fuel autonomy in litres instead of hours at the expected load. The tank that looked large runs dry on the second night of a cyclone outage.
- Choosing one large set for a remote site to save capital. A single failure leaves the site dark until a service crew can travel.
What to send us
Send the facility type and its essential load list, or the full load list if classification has not been done, together with the single-line diagram and photographs of the switchroom and proposed generator location. For emergency or remote work, state the location, road access, available fuel supply, expected duration and the communication link available for monitoring. Include any tender specification or departmental standard the installation must meet. Send your public-sector or remote power requirement.
Questions engineers ask
What size generator does a government office need?
Size it for the classified essential load, usually lighting, IT and records, lifts, pumps and selected areas, rather than the full building. For a typical district-level office this is often 25 to 40 per cent of the connected load, and the classification should be approved by the department before the tender is issued.
How much fuel should a public building generator hold?
Enough to run the essential load for the longest credible outage in the area, which in cyclone-prone districts may be 24 to 48 hours, with a refuelling plan beyond that. State the requirement in hours at expected load and convert it to tank size using the set’s consumption data.
Can a remote site run on solar instead of diesel?
Usually a combination works best. Solar with battery storage carries the daytime and part of the night, and a small generator runs a few hours a day at good load to cover the rest and recharge the batteries. The generator remains essential for cloudy periods and as a backup to the inverter.
What documents should a tender require for a generator installation?
The manufacturer’s test certificate, the CPCB IV+ approval reference for new sets up to 800 kW, the installation single-line diagram and earth resistance results. It should also require the AMF transfer test record, the load test record and an operation and maintenance manual with a service schedule.
Technical content reviewed by Srinivas Reddy, Managing Partner, Reddy Generators. Last updated 19 October 2026.