Diesel Generator Installation

Diesel Generator Installation

The purpose of this article is to provide a basic guide to the various facets that form the basis of installing a diesel generator in a building plant room. Any work conducted on a generator is to be done by a certified technician to the relevant local legislation’s and standards. The diesel generators operational manual must be referred too, ensuring that unit specific parameters are met.

Elements (not limited to) contributing to the installation of a generator are:

  • Layout
  • Ventilation
  • Noise attenuation
  • Foundations
  • Fuel supply
  • Exhaust system
  • Cabling 



The layout of a generator in a building will vary with each project. However, the basic principles remain the same.

Allowing for adequate space around the generator is an important consideration, to provide for common functions such as inspections, maintenance and repairs of the generator and or auxiliaries . Ideally 3 metres of space around the generator is to be provided.

A load bearing beam above the centre line of the engine is essential to allow for any repairs/replacement of major components.

If the building is in the design stage it may be wise to allow for future increased load requirements requiring larger generator(s) by proving larger space than initially required. This will avoid costly solutions/modifications in the future.



Diesel Generators require adequate air flow for:

  • Ventilation
  • Cooling
  • Combustion

Generators radiate heat hence it is essential to have the air supply renewed to avoid temperature rises in the plant room.

The most common design (based on radiator mounted on set) is to have the following:

  • Air drawn in via the alternator end via air inlet aperture wall
  • Air inlet aperture wall to be as close to ground level as possible to avoid pulling dust, water etc.… avoiding areas where there could be possible obstruction
  • The cooling fan to be the pressure type allowing air to flow via rear of alternator across generator
  • The radiators outside face as close to the air outlet aperture wall as possible
  • The air outlet aperture to be of equal area of the radiator
  • A flanged duct should be placed from between the wall and the radiator to avoid recirculation of hot air


Noise attenuation

The noise emitted by the diesel generator plant room to surrounding areas must meet local standards.

The sources of noise in a plant room are:

  • Engine (greatest contributor)
  • Exhaust
  • Radiator fan

The location of the plant room at design phase can assist in limiting the impact of noise. Offices and other noise sensitive areas relative to the plant room can (where possible) can be designed such that there are buffer zones separating them.

Noise control methods:

  • Barrier walls
  • Vibro – isolated inertia block
  • Residential multi step exhaust muffler
  • Acoustic lovres
  • Double glazed windows
  • Flexible sections for service items



It is critical that the diesel generator is supported by a suitable foundation. The structure and mass of the foundation must be able to absorb any vibrations created.  A structural engineer specialising in this area must be consulted. Together with the assigned plant consultant/contractor the design of the foundation is developed.

Design inputs:

  • Weight of diesel generator
  • Engine speed
  • Mounting/fixing of the engine and alternator
  • Static and dynamic traits of diesel generator
  • Operating temp of the plant room (heat transferred to concrete can create tensile stresses)
  • Subsoil composition


Fuel Supply

The basis of a typical fuel system is to have enough fuel to cater for the required operation of the generator without interruption.

A fuel system integrates the following equipment and specification

  • Storage tank
    • Manufactured from sheet metal
    • Eternal galvanised
    • Located close as possible to the plant room
      • Adjacent
      • Underground
      • Easy access for delivery tankers
    • Fuel level indicator
    • Filling connection
    • Service tank overflow connection
    • Manhole
    • Breather
    • Drain cock
    • Transfer pump connection
    • Piping steel tubes


  • Daily Service tank
    • Manufactured from sheet metal
    • Eternal galvanised
    • Located
      • Adjacent to the set
      • Base plate
    • Filling connection
    • Outlet connection
    • Overflow connection
    • Drain cock
    • Breather
    • Level indicator
    • Transfer pump switch
    • High level alarm


  • Pump to transfer fuel from storage tank to daily tank
    • Located by the service tank
    • Signal float level in the service tank


 Exhaust systems 

The diesel generators exhaust system performs the following:

  • Transfer of combustion gases to the atmosphere
  • Attenuates the noise generated by the pressure pulses of gases
  • Avoids large feedback pressure on the engine

The exhaust system pipes combusted gas from the engine exhaust manifold (or turbocharger) to a muffler (silencer) into the atmosphere.

Noise produced by the exhaust system must comply to local regulations. Attenuation is achieved using muffler(s).

Piping is made of steel. The diameter of pipe will depend on the length required and engine model. Engine manufactures provide tabulated data of diameter versus length of pipe run along with maximum back pressures allowed for their engines.

Best practice:

  • Short exhaust pipe runs with minimum bends
  • Stainless steel flexible section located close to the engine manifold to act as a vibration break
  • Flexible sections well sealed
  • Exhaust pipe terminated outside the building
  • Exhaust pipe passing through combustible areas are to be insulated
  • Horizontal pipe runs to slope down away from engine
  • Lag pipes and mufflers
  • Muffler(s) to be located outside building


Cabling (low voltage PVC insulated)


  • Load cables – heavy duty
  • Control cables – lighter duty

Cable size factors:

  • Load
  • Temperature
  • Protection type against overload
  • Fault level
  • Voltage drop

Cable installation methods:

  • Attached to structural surfaces
  • In trenches
  • On cable trays
  • In underground ducts
  • In plastic conduits

Cabling best practice:

  • Segregation – minimise interference
  • Grouping avoided/minimised – de-rates apply to cables grouped
  • Cable glanding using non-ferrous material
  • Cable termination:
    • Good electrical contact of cable conductor and equipment
    • Provide support and secure cable
    • Control electrical stresses produced on the cable



The content of this article is a brief guide of the main elements contributing to the diesel generator installation. Installing a diesel generator in a building plant room is complex requiring the analysis of many variables to produce the desired outcome. It is only to be conducted by professional organisations specialising in this field, who have the required experience and resources.


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