In short. A generator placed on a plinth is not an installed power system. Installation is the work that turns equipment into infrastructure: positioning on a suitable foundation and mounts, connecting exhaust, fuel and ventilation without stressing the engine, terminating cables correctly, earthing body and neutral, interfacing the controller with the ATS or AMF panel, and verifying every connection before the first start. Each interface is recorded so that commissioning tests a known system.
Installation is where equipment becomes infrastructure
The same engine, alternator and controller can run reliably for fifteen years at one site and fail repeatedly at another. The difference is the installation: air path, exhaust restriction, fuel delivery, termination quality, earthing and the transfer interface. Installation follows the manufacturer’s instructions and the approved drawings at their current revision, and where the site differs from the drawings the difference is assessed and recorded rather than settled by an unrecorded field decision. The planning that should precede the work is described in installation planning.
On arrival, check the set against the order: model, engine and alternator serial numbers, voltage, frequency, rating and controller type on the nameplates, and the drawing revision the site was built to. Inspect for transport damage and leaks, confirm the loose-supplied items are present, and confirm plinth level, openings, sleeves, cable route and fuel system once more. A mismatch found now costs an hour; found after cabling it costs a week.
Foundation and mounting
A set needs a foundation that carries its static weight, resists the dynamic forces of a reciprocating engine and keeps the set level and above water. For sets on anti-vibration mounts between engine-alternator and base frame, the common arrangement, a reinforced concrete plinth 150 to 200 mm above floor is usually adequate, confirmed against the manufacturer’s foundation guidance. Where the set is rigidly mounted or vibration transmission matters, an inertia block of around one and a half to two times the set’s mass is the traditional rule, confirmed by a structural engineer for rooftops and suspended floors. The plinth extends beyond the base frame, has a drainage fall and carries the anchor bolts at the drawing positions. Mounts are levelled and left free to work; a mount bolted solid with packing underneath is no mount at all.
Connecting the mechanical interfaces
| Interface | Correct practice | Verification before start |
|---|---|---|
| Exhaust | Flexible bellows at the turbo outlet, pipe weight on building supports, expansion allowed, insulated inside the room, condensate drain, no load on the engine flange | Pipe free at supports when cold, joints sealed, route within backpressure budget |
| Ventilation | Radiator ducted to the discharge opening with a flexible connection, inlet unobstructed, no recirculation path | Duct sealed, louvres open, no obstruction within the stated clearance |
| Fuel | Flexible hoses at the engine, suction line rising to the engine with no high points, return to tank, isolation valves, day-tank level control wired and tested | Lines primed and bled, no leaks under transfer-pump pressure, tank vent clear |
| Batteries | Correct capacity and polarity, terminals clean and tight, charger connected and set to the battery type | Open-circuit voltage and charger output measured |
Detail is on the exhaust system and fuel system pages. Two faults recur on installations we are called to rescue: pipe weight hanging on the exhaust bellows, and a suction line with a high point that collects air and stops the engine after twenty minutes.
Cables and terminations
Generator output cables carry the full set current and are not ordinary building wiring. The size follows the approved design for current, voltage drop and short-circuit withstand, as set out in generator cable sizing; installation quality decides whether that design is realised. Single-core cables are grouped in trefoil and glanded through non-magnetic plates, bending radii are respected, lugs match the conductor and are crimped with the correct die and bolted at the correct torque onto clean busbar, and cable supports take the mechanical load rather than the alternator terminal box. After termination the installer records insulation resistance, continuity and phase sequence and photographs the terminations before covers go on. A good cable design defeated by a loose lug produces a hot joint that fails under the first long outage.
Earthing and neutral
Indian practice under IS 3043 and the CEA regulations provides two independent earth electrodes for the generator body and, where the generator neutral is earthed at the set, separate electrodes for the neutral, interconnected to the site earthing system as the design requires. The installer connects the body earth to the frame and the alternator, connects or does not connect the neutral according to the three-pole or four-pole transfer design, and measures electrode resistance before the set is energised. The neutral arrangement is a design decision, explained in earthing and neutral grounding; the installation must match it exactly, because an unearthed neutral on generator supply or a parallel neutral path on utility supply are both dangerous and both invisible until something fails.
Controller and transfer interface
The generator controller and the ATS or AMF panel exchange a handful of signals: mains-available sensing, remote start, generator-available, breaker status and alarms. These are wired to the panel drawings, labelled at both ends and checked for continuity and polarity before power is applied. Timers for start delay, warm-up, transfer, retransfer and cool-down are set to the design values and recorded. Interlocks that prevent the generator breaker and the utility breaker closing together are proven mechanically and electrically with the set stopped. Only then is the automatic sequence tested, and that test is part of commissioning rather than installation.
Installation completion versus commissioning
Installation is complete when every interface is connected, inspected and recorded: the as-installed drawings marked up, the cable test results, the earth resistance, the fuel and coolant fills, the torque record on terminations, and a list of any item left incomplete or changed from the drawing. Commissioning then tests the functions and performance of that recorded system under defined conditions, as described in generator commissioning. Mixing the two, by starting the engine to see if it works before the checks are done, is how installation defects become commissioning mysteries. A set moved to a new site keeps its nameplate but loses its installation, so every interface above is re-engineered and re-verified; see generator relocation.
Related photographs and videos
Common mistakes
- Supporting exhaust pipe from the engine bellows; the bellows tears or the turbocharger housing cracks within months of daily running.
- Running the fuel suction line with a high point or an unsupported loop; air collects, the engine starves and stops under load after a short run.
- Crimping lugs with the wrong die and skipping the torque check; a termination overheats under the first sustained load and the alternator terminal box burns.
- Earthing the neutral at the set when the design called for a three-pole transfer with a common neutral earth; circulating neutral currents and nuisance earth-fault trips follow.
What to send us
For a new installation send the set model and general arrangement drawing, the site survey report, the approved single-line diagram and transfer scheme, the foundation drawing, photos of the plinth, room and cable route as they stand, and the names of the civil and electrical contractors on site. For a relocation add photos of the existing installation and the controller settings pages. Use the generator sales enquiry and we will confirm scope, sequence and dates.
Questions engineers ask
What kind of foundation does a diesel generator need?
A level reinforced concrete plinth above floor and flood level, sized from the manufacturer’s foundation guidance for the set’s weight and anchor positions. Sets on internal anti-vibration mounts usually need only a plinth; rigidly mounted sets or sensitive structures need an inertia block, traditionally one and a half to two times the set’s mass, confirmed by a structural engineer.
How far can the generator be from the main switchboard?
As far as the cable design allows for voltage drop at running and motor-starting load, which in practice means a few tens of metres before cable size and cost rise sharply. Longer runs are possible with larger or parallel cables, but each extra metre is copper and voltage drop, so the position is chosen with the cable route in mind.
How many earth pits does a generator need?
Indian practice provides two independent electrodes for the body earth and, where the neutral is earthed at the set, two for the neutral, all bonded into the site earthing system as the design requires. The number is set by the design and the resistance achieved, not by a fixed rule, and the resistance is measured before energisation.
Can I start the generator as soon as it is connected?
Not before the pre-start checks: oil and coolant levels, fuel primed and leak-free, battery voltage, cable insulation resistance and phase sequence, earth connections, exhaust free of obstruction and the transfer interlocks proven. Starting first and checking later is how a wiring fault becomes a damaged alternator.
Technical content reviewed by Srinivas Reddy, Managing Partner, Reddy Generators. Last updated 19 October 2026.