Views: 0 Author: Site Editor Publish Time: 2026-06-09 Origin: Site
A diesel generator is not plug-and-play equipment. The quality of its installation determines how reliably it will start, how long it will last, and whether it is safe for the people who operate and maintain it. A generator installed with inadequate ventilation will overheat within minutes of full-load operation. A generator with an undersized exhaust system will back-pressure the turbocharger and reduce output. A generator without correct earthing is a shock hazard to anyone who touches its enclosure.
Most generator failures in the first year of operation are not caused by defective equipment -- they are caused by defective installation. This guide covers every stage of the installation process from site selection to commissioning, with the specific requirements and dimensions that distinguish a correct installation from a dangerous one.
Note: generator installation involves work on high-voltage electrical systems. The electrical connection work described in this guide must be performed by a qualified electrician. The mechanical installation and foundation work can be supervised by a competent project manager with this guide as a reference.
Site selection is the most consequential installation decision. A poor location creates problems that cannot be corrected after the generator is installed -- inadequate ventilation, noise violations, fuel spill risk, difficult maintenance access. Evaluate the following before committing to a location.
⚲ Distance from Load Centre
The generator should be located as close to the main distribution board (MDB) as practical. Every additional metre of cable run adds resistance (voltage drop) and cost. The maximum acceptable voltage drop in the generator supply cable is typically 1.5-2.5% of nominal voltage at full rated current. For a 100kW generator at 380V three-phase, calculate cable size based on this voltage drop limit. Cable runs above 50m typically require upsizing the cable cross-section significantly.
⚲ Noise-Sensitive Receptors
Identify all noise-sensitive locations within 100m of the proposed site: residential properties, hotel guest rooms, offices, schools, hospitals. Map the distance and direction to each. Use the generator's specified noise level at 1m (from the datasheet) and calculate the expected noise level at each receptor using the inverse square law (noise falls 6 dB(A) for every doubling of distance in open air). If calculated noise at any receptor exceeds local planning limits, either relocate the generator, specify a quieter canopy type, or provide acoustic screening.
⚲ Fuel Delivery Access
The generator site must be accessible to a fuel tanker. A diesel delivery tanker typically requires a turning radius of 12-15m and overhead clearance of 4.5m. The maximum fuel hose reach from tanker to tank is typically 30-40m. If the site is not directly accessible to a tanker, you will need an above-ground bulk storage tank at road level with a pump and underground line to the generator -- a significantly more expensive and complex fuel system.
⚲ Maintenance Access Clearances
Leave minimum clearance around the generator for maintenance: 1.0m on all sides for a canopy unit (minimum -- 1.5m preferred); 1.5m at the engine end for injector and filter access; 2.0m overhead clearance above the generator for crane or hoist access if required for major service. A generator installed with 200mm clearance to a wall cannot be serviced correctly -- the first service call will confirm this expensively.
⚠ The most common site selection mistake: the basement plant room with no exhaust route
Buildings frequently allocate basement space for the generator as an afterthought. The generator arrives on site and there is no practical route for the exhaust to exit the building. Exhaust must exit to outside atmosphere -- it cannot vent into the building interior or into an enclosed plant room without full extract ventilation. Plan the exhaust route before the generator is ordered. Routing a 150mm diameter flexible exhaust pipe through a building structure after construction is expensive, disruptive, and sometimes impossible.
The generator must be supported on a surface capable of carrying its wet weight (engine oil, coolant, and full fuel tank) without deflection or vibration amplification. An inadequate foundation is the most common cause of vibration-related fatigue failures in generator installations.
Concrete plinth (recommended for all permanent installations): A reinforced concrete plinth isolates the generator from the building floor slab, provides a level mounting surface, and prevents oil spills reaching the main floor. Minimum plinth specification: 150mm deep concrete (C20/25 grade minimum); reinforced with 10mm steel bar at 200mm centres both ways; plinth dimensions = generator base frame + 150mm each side. The plinth surface must be level within 5mm across the full length.
Anti-vibration mounts: Anti-vibration mounts are fitted between the generator base frame and the plinth surface. They isolate structural-borne vibration from the building fabric. Mounts are specified by the generator manufacturer based on set weight and running speed. Never substitute a different mount type without manufacturer approval -- incorrect mounts allow resonance at engine firing frequency, causing fatigue cracks in the generator base frame and building structure. For canopy-mounted generators, mounts are typically factory-fitted.
Generator Size | Typical Wet Weight | Plinth Minimum Size | Anti-Vibration Mount Type |
20-30 kW | 400-600 kg | 1,800 x 700 x 150mm | Rubber sandwich mounts |
60-100 kW | 900-1,500 kg | 2,800 x 1,000 x 150mm | Rubber sandwich or |
150-200 kW | 1,800-2,800 kg | 3,500 x 1,200 x 150mm | Level-adjusting rubber |
300-500 kW | 3,500-6,000 kg | 5,000 x 1,600 x 200mm | Spring mounts |
750-1,000 kW | 7,000-12,000 kg | 6,500 x 2,200 x 250mm | Spring mounts; |
Engine overheating is the most common installation-related failure. It is caused by inadequate ventilation in the generator plant room -- the room heats up, effective ambient temperature rises above the generator's rated ambient, and the engine shuts down on high temperature protection.
A diesel generator radiates heat from two sources: the radiator (cooling system heat rejection) and the engine block surface (convective heat). The plant room must remove this heat continuously at rated load.
Airflow requirement calculation: The required airflow through the plant room can be estimated from the generator's heat rejection figure (published in the engine datasheet as 'radiator air flow' in m3/min or cfm). As a rule of thumb, size the ventilation opening to limit the plant room temperature rise to maximum 5 deg C above inlet air temperature. For a 100kW generator: typical required airflow = 15-25 m3/min. For a 500kW generator: 60-100 m3/min.
☀ Inlet Air Opening
The air inlet opening must be sized to supply the required airflow without excessive velocity (high velocity creates back-pressure that reduces cooling airflow through the radiator). Maximum air velocity at the inlet louvre face: 2.5-3.5 m/s. For a 100kW generator requiring 20 m3/min, the required inlet area = 20 / (3.0 x 60) = 0.11 m2 = approximately 330mm x 330mm clear opening. For canopy generators, the inlet and outlet openings on the canopy are pre-sized by the manufacturer -- do not block or restrict them.
☀ Outlet Air Opening
The outlet opening should be at least 1.2x the area of the inlet opening to ensure air flows from inlet to outlet without recirculation. The outlet must be positioned so that hot air exhausted from the plant room cannot re-enter through the inlet. Inlet low on the cool side of the room; outlet high on the hot side -- this creates a natural convection assist that supplements forced radiator airflow.
⚠ The recirculation trap -- hot air re-entering the inlet
If the plant room outlet is positioned on the same wall or adjacent wall to the inlet, hot exhaust air can be drawn back into the inlet by the radiator fan's suction. This raises the effective ambient temperature progressively until the generator shuts down on overheating -- often within 20-30 minutes of full load operation. Position inlet and outlet on opposite sides of the plant room, or use baffled duct arrangements to ensure complete separation of supply and exhaust air paths.
The exhaust system carries hot combustion gases (typically 450-600 deg C) from the engine turbocharger outlet to the atmosphere outside the building. Incorrect exhaust design reduces generator output, damages the turbocharger, and creates carbon monoxide hazard.
Step 4a: Flexible Bellows Connection
The first component of the exhaust system must be a flexible stainless steel bellows coupling between the engine exhaust outlet and the rigid exhaust pipe. The flexible coupling absorbs engine vibration and thermal expansion movement -- without it, rigid pipe connected directly to the engine will crack at the flanged joint within months. Minimum flexible coupling length: 300mm for generators up to 200kW; 500mm for generators above 200kW.
Step 4b: Pipe Sizing
The exhaust pipe diameter must match the engine outlet size. Do not reduce the pipe diameter below the engine outlet -- restriction increases exhaust back-pressure, reduces turbocharger efficiency, and causes black smoke under load. Maximum allowable exhaust back-pressure is specified by the engine manufacturer -- typically 5-10 kPa. For long exhaust runs or multiple bends, calculate actual back-pressure. As a guide: maximum exhaust pipe length without upsizing = 6m for 100kW generator; 4m for 200kW; 3m for 400kW (at standard pipe diameter). Each 90-degree bend adds approximately 1m equivalent length.
Step 4c: Silencer Selection and Positioning
The silencer (muffler) reduces exhaust noise from the engine's natural level (typically 105-115 dB(A) at exhaust outlet) to an acceptable level. Three grades: industrial silencer (15-20 dB(A) attenuation); residential silencer (25-30 dB(A) attenuation); critical silencer (35-40 dB(A) attenuation). For generators within 50m of residential areas, specify a residential or critical silencer. Position the silencer outside the plant room where possible -- a hot silencer inside a plant room adds to the room heat load.
Step 4d: Exhaust Outlet Location and Safety
The exhaust outlet must be: minimum 3m above ground level or minimum 1m above any building opening (window, door, air inlet) within 5m; directed away from public walkways and building entrances; fitted with a rain cap or turn-down to prevent water entry; 500mm minimum clearance from any combustible material. Exhaust gas contains carbon monoxide -- the outlet must discharge to open atmosphere, not into enclosed spaces, car parks, or areas where people may be present.
Exhaust pipe thermal insulation: Exhaust pipe surfaces reach 300-500 deg C in operation. All exhaust pipe surfaces within 2m of head height or within reach of maintenance personnel must be insulated with mineral wool or ceramic fibre insulation wrapped in stainless steel cladding. This is a safety requirement -- bare exhaust pipe at operating temperature causes severe contact burns instantly.
Sub-base tank to day tank connection: Most generators have an integral sub-base fuel tank. For installations with a separate bulk storage tank, a day tank (small header tank adjacent to the generator) is filled by gravity or a transfer pump from the bulk storage. The day tank fuel supply line to the generator must use flexible connections at the generator -- rigid pipe connected directly to the engine will fatigue from vibration. Specify fuel-rated flexible stainless steel hose for the final 500mm connection to the engine.
Fuel return line: Diesel injection systems return unused fuel to the tank. Ensure the return line from the engine connects to the top of the day tank or sub-base tank -- not to the bottom. A return line connected to the tank bottom will aerate the fuel if the return line outlet is above fuel level.
Spill containment: All fuel connections must be within a bunded area capable of containing 110% of the tank volume. Every fuel-carrying connection point must have a drip tray or be within the bunded area. A single fuel leak at an uncontained connection point can cause a fire or significant environmental contamination.
⚠ Electrical work must be performed by a qualified electrician
The following describes what must be done -- not how to do it safely without electrical training. All connections to the generator output terminals, ATS, and distribution board must be made by a competent electrician with appropriate safety equipment (insulated tools, voltage tester, appropriate PPE). Never work on live electrical circuits.
Cable sizing: The supply cable from generator to ATS or distribution board must be sized for: (1) rated current at full load; (2) voltage drop not exceeding 2.5% at rated current; (3) short circuit fault current withstand for the protection relay coordination design. For a 100kW generator at 380V three-phase: rated current = 100,000 / (1.732 x 380 x 0.8) = 190A. Minimum cable size for 190A at 25 deg C buried: 95mm2 copper. Adjust for ambient temperature, grouping, and cable length.
ATS wiring: The Automatic Transfer Switch connects the generator output, the grid supply, and the load. It must be rated for the full generator fault level, not just the normal operating current. The ATS wiring sequence: generator output terminals to ATS generator input; ATS load output to main distribution board; grid supply to ATS mains input. The ATS control wiring connects to the generator control panel's remote start output and mains sensing input.
Earthing (grounding): The generator frame, alternator frame, and neutral point must all be correctly earthed. The earth electrode (earth rod or earth plate buried in the ground) must achieve an earth resistance of 1 ohm or less for most commercial applications. The main protective earth conductor from generator frame to earth electrode must be sized at minimum 50% of the phase conductor cross-section (minimum 16mm2 copper for any installation). Earthing must be verified by an earth resistance test before commissioning.
Commissioning is the systematic verification that every aspect of the installation is complete and correct before the generator enters service. Do not skip commissioning steps -- each one catches a specific category of installation error.
Commissioning Check | What to Verify | Method |
Pre-start inspection | All mechanical connections secure; | Visual walkround; |
Earthing verification | Earth resistance <=1 ohm; | Earth resistance tester (Megger or equivalent); |
Insulation resistance | All wiring insulation resistance | Insulation resistance tester |
No-load first start | Engine starts cleanly; | Start engine; observe control panel; |
Load test (step loading) | Voltage and frequency stable at | Apply load bank or actual facility load; |
ATS function test | Simulate mains failure; | Disconnect mains supply at ATS; |
Protection system test | Confirm all alarms and shutdowns | Simulate each protection input |
Documentation | Complete installation record: | Written record filed with |
✔ The commissioning certificate: what it must contain
A commissioning certificate should be issued for every generator installation by the commissioning engineer. It must record: installation date and location; generator make, model, and serial number; earth resistance test result; insulation resistance test result; no-load voltage and frequency; full-load voltage, frequency, and current on all three phases; ATS transfer time measured; protection system tests completed and results; any deficiencies noted and corrective actions taken; commissioning engineer signature and qualification. This document is essential for warranty claims and insurance purposes.
Every Leading Power generator is supplied with a complete installation manual covering the mechanical and electrical installation requirements specific to that model. We also provide pre-delivery technical consultation to help customers plan their installation correctly before the generator arrives on site.
· Installation manual: supplied with every generator -- covers foundation requirements, ventilation calculation, exhaust sizing, electrical connection diagrams, and earthing requirements for the specific model
· Pre-delivery consultation: send us your plant room dimensions, proposed exhaust route, and electrical single-line diagram -- our engineering team will review and confirm the design is correct before generator dispatch
· Exhaust system specification: we provide a detailed exhaust system specification (pipe diameter, silencer grade, flexible coupling size) matched to each generator output and site conditions
· Commissioning support: Leading Power or authorised service partner commissioning engineers available in Nigeria, Kenya, Ghana, Tanzania, Saudi Arabia, UAE, and Indonesia
· Installation checklist: printable installation checklist for site contractors available on request -- ensures no installation step is overlooked
· 24-hour technical support: installation questions answered within 24 hours during the installation and commissioning period
Leading Power is a CE-certified diesel generator manufacturer based in Fu'an, Fujian, China. Established in 2008. 5kW-3,000kW generator sets supplied to 60+ countries. Complete installation documentation, pre-delivery technical review, and commissioning support available for all Leading Power generators.
