Generator Site Planning Checklist: Clearances, Access, Fuel Delivery and Exhaust Direction

In short. A good generator location is fixed by six things you can measure with a tape and a level, before anything is bought. They are: clear space around the set for service and airflow, a tanker route to a safe fill point, an exhaust outlet well away from windows and intakes at the right height, room for earth pits and short cable routes, a plinth above flood level with drainage, and, on roofs or in basements, structure, access and ventilation. This page gives the dimensions to check and a site-survey sheet to record them.

Who this page is for: architects, MEP consultants, builders, facility managers and site engineers choosing or checking a DG location. The delivery sequence, crane survey, permits and coordination with other trades are covered on our installation planning page; this page is about the space itself.

Key facts

Keep at least 1.0 m clear on the non-service sides of a canopy set, and 1.5 m on the door and control-panel sides. Door swing must open fully, to 90° or more.
Keep the radiator discharge free for at least 2–3 m, or about twice the radiator height, unless it is ducted. Never discharge against a wall closer than this.
Indoor rooms need an air inlet of about 1.5 times the radiator core area and an outlet of about 1.25 times the core area. Confirm against the maker’s cooling-air figure.
Keep the exhaust outlet at least 3 m from any openable window, door or fresh-air intake, at the stack height H = h + 0.2 × √kVA, pointing away from the building.
Earth electrodes should be spaced at least about twice their driven length apart: for 3 m electrodes, about 6 m. Body and neutral pits are separate.
Set the plinth top at least 300 mm above the highest flood level recorded at the site, with a drainage fall away from the set.

1. Clearances around the set

Outdoor canopy sets

Side	Minimum clear space	Why
Control-panel and service-door side	1.5 m, plus full door swing	Room to stand, open the doors fully, withdraw filters and work on the panel safely
Opposite service side	1.0 m	Access to the far side for inspection, cleaning and leak checks
Radiator discharge end	2–3 m clear, or about twice the radiator height	Hot air must leave and not recirculate to the intake
Air intake end or sides	1.0–1.5 m	Free inflow of cool air; louvres must not face a wall closely
Above the canopy	Nothing overhead within about 1 m; clear lifting path	Exhaust heat, rain cap, lifting for future replacement
Between two sets	At least 1.5 m, and more if both service sides face each other	Service access and no hot-air exchange between sets

Indoor generator rooms

Width: set width + 1.0 m on one side + 1.5 m on the panel side, as a minimum.
Length: set length + 1.0 m at the alternator end + the radiator-to-outlet air path. Allow at least 1.0 m to the outlet louvre or attenuator, or a duct flange fitted directly to the radiator.
Height: top of the set + exhaust run, lagging and silencer + about 1 m for lifting gear. A lifting beam or hook point over the engine helps future overhauls.
Doors: outward-opening, wide enough to bring the largest single component in, and in practice for the whole set if it may ever be replaced.
Cooling air: inlet opening about 1.5 times the radiator core area, outlet about 1.25 times. Low inlet, high outlet. Inlet and outlet on different walls, so air sweeps across the set, not from one hole straight to the next.

2. Fuel: tanker route and fill point

Tanker route: a firm road at least 3.5 m wide, with headroom of about 4 m and a turning space. A tanker should not reverse along a public road or through a crowded car park.
Hose reach: place the fill point within the tanker’s hose reach, typically 15–30 m. Measure the actual hose route, not the straight line.
Fill point: outside the building, at a lockable fill box with spill containment, a level gauge visible to the person filling, and an overfill alarm or vent whistle.
Day tank: sized within what the fire NOC and storage limits allow, with a bund or tray that can hold at least the tank’s full contents.
Fuel lines: short and supported, with an isolation valve at the tank. Keep them clear of the exhaust and hot surfaces.
Security: a lockable cap and a log of every delivery against the gauge. See fuel theft and refuelling control.

3. Exhaust: direction, height and neighbours

Height: stack outlet at H = h + 0.2 × √kVA metres, where h is the building height. Use the figure in your consent if it is higher.
Distance: at least 3 m from openable windows, doors and intakes, measured from the outlet, not from the pipe.
Direction: vertical discharge with a rain cap that does not deflect the gas downward. Do not discharge horizontally towards a building, a walkway or a neighbour’s façade.
Intakes: keep the outlet well clear of air-handling unit and ventilation intakes, including your own generator’s cooling-air intake. Hot exhaust drawn into the radiator air path raises coolant temperature.
Wind: in Telangana and Andhra Pradesh the prevailing wind is broadly south-westerly during the monsoon and north-easterly in the cooler months. Where you have a choice, place the outlet downwind of occupied areas for the longest-running season.
Route: short runs with few bends, flexible connector at the engine, lagging inside rooms, and a condensate drain at the low point. Long runs need a back-pressure check.

4. Earth pits and cable routes

Pits: separate pits for neutral and body earthing, each with a test point. Keep them away from foundations and from lightning-protection electrodes, with electrodes spaced about twice their driven length apart.
Location: in soil that can be kept moist and can be reached for testing. A pit under a paved car park that nobody can open will not be tested.
Cable route: measure the actual route from the alternator terminals to the changeover. Longer routes increase voltage drop and reduce fault current at the far end, which affects breaker tripping. Check them with the cable size chart.
Trenches: buried LV cables at about 750 mm depth with protection, crossing water and drainage lines at right angles, and with marker tape and route markers.
Entry: sealed cable entries to the canopy and the room, so neither water nor rodents follow the cable in.

5. Flood level and drainage

Ask the building owner or neighbours for the highest water level seen, and look for marks on walls. Plinth top should be at least 300 mm above it.
Electrical equipment must be installed above the highest flood level. In low-lying parts of Hyderabad and in coastal districts, that often rules out basements.
Give the plinth a fall away from the set, and keep surrounding drains clear. An oil interceptor or a bunded drain stops spills reaching the storm drain.
Keep the fill point, the day tank vent and cable pits above flood level as well, not just the set.

6. Rooftops and basements

Location	Must check	Common problem
Rooftop or terrace	Slab capacity for the set’s wet weight, fuel and plinth, confirmed by the structural engineer. Spring or rubber mounts suited to the slab. Crane access and lift plan. Fuel supply height. Exhaust clearance from the building’s own intakes.	Vibration and hum in the rooms below; fuel pump unable to lift from a ground tank
Basement	Flood level and pumping. Ducted cooling air in and out. Exhaust route to the required height. Fire separation and fire NOC. Access for replacement.	Hot-air recirculation, overheating, flooding; set cannot be removed without breaking a wall
Podium or car-park level	Headroom for the exhaust and lifting. Vehicle impact protection. Ventilation to open air.	Exhaust discharging into the parking area; no tanker access
Open ground beside the building	Distance from windows. Noise towards neighbours. Plinth and drainage.	Discharge facing a neighbour’s house; set too close to a bedroom window

Worked example (illustrative): surveying a car-park site for a 320 kVA canopy set

The site. A five-storey commercial building, 15 m high, wants a 320 kVA canopy set in a ground-level car-park corner. The canopy is about 4.2 m long, 1.4 m wide and 2.0 m high.

Footprint with clearances. Length 4.2 + 1.0 (alternator and intake end) + 2.5 (radiator discharge) = 7.7 m. Width 1.4 + 1.5 (panel side) + 1.0 (far side) = 3.9 m. The corner measures 8.5 m × 4.5 m, so it passes, with 0.8 m and 0.6 m to spare.
Radiator discharge. The first layout pointed the discharge at a wall 1.2 m away. Rotating the set 180° sends hot air towards the open car-park aisle, and the intake end now faces the wall, 1.2 m away, which is above the 1.0 m minimum.
Exhaust. H = 15 + 0.2 × √320 = 15 + 0.2 × 17.89 = 15 + 3.58 = 18.6 m. The stack is carried up the building’s rear face to 18.6 m. Its outlet is 4.5 m from the nearest openable window on the top floor, so the 3 m minimum is met. It is also well clear of the rooftop air-handling intake.
Fuel. The tanker parks at the service gate. The measured hose route to the proposed fill box is 22 m, within a typical 30 m hose. The fill box goes on the outer face of the car-park wall, with a bund under the day tank.
Earth pits. Four pits — two body, two neutral — are planned in the landscaped strip beside the car park, using 3 m electrodes spaced 6 m apart, 2 m from the building foundation and clear of the lightning pits.
Flood level. A water mark 0.45 m high is found on the car-park wall from a past downpour. Plinth top = 0.45 + 0.30 = 0.75 m above car-park floor, with a fall to the drain. The cable trench and fill box are raised to match.
Cable. The measured route to the changeover in the ground-floor electrical room is 38 m. That figure goes to the cable sizing and breaker check before the single-line diagram is drawn.

Result: one change, rotating the set, avoided a recirculation problem that would have caused summer overheating trips. Everything else was confirmed with a tape measure in under two hours.

Generator site-survey checklist (dimensioned)

Site	Proposed set kVA	Set L × W × H (m)	Building height h (m)	Surveyed by / date

Item	Target	Measured	OK (✓/✗)	Action
Clearance: panel / door side	≥ 1.5 m + full door swing
Clearance: opposite side	≥ 1.0 m
Clearance: radiator discharge	≥ 2–3 m clear, or ducted
Clearance: intake side	≥ 1.0–1.5 m
Overhead clearance and lifting path	≥ 1 m; clear lift
Indoor: inlet opening area	≈ 1.5 × radiator core area
Indoor: outlet opening area	≈ 1.25 × radiator core area
Tanker road width / headroom	≥ 3.5 m / ≈ 4 m
Hose route to fill point	Within hose length (15–30 m)
Fill point: lockable, contained, gauge visible	Yes
Stack height required H = h + 0.2√kVA	H = ____ m
Exhaust outlet to nearest window / door / intake	≥ 3 m
Exhaust direction away from building and neighbours	Yes
Earth pits: number, electrode length, spacing	Separate body / neutral; spacing ≈ 2 × length
Earth pits: distance from foundation and lightning pits	Clear; testable
Cable route length to changeover	Record actual (m)
Highest flood level observed	Record (m)
Plinth top above flood level	≥ 0.3 m
Drainage fall and oil interception	Yes
Rooftop: slab capacity confirmed by structural engineer	Yes (if applicable)
Basement: ducted air, pumping, removal route	Yes (if applicable)
Distance to nearest neighbour’s window	Record (m)

Attach: a sketch with north arrow and dimensions, and photographs of the location, the access route, the fill point position, the exhaust route and the earth pit area.

Exceptions and cautions

The dimensions here are good-practice minimums for typical sets. The maker’s installation manual, your fire NOC and your consent conditions can require more; follow the largest figure.
Large sets and multi-set plants need a full airflow and acoustic design, not rules of thumb. Ducted radiator systems change the clearance rules entirely.
Never reduce the radiator discharge clearance by adding a deflector without checking airflow. A badly placed deflector can be worse than the wall.
Rooftop installations always need the structural engineer’s written confirmation. A slab that looks thick may not be designed for a concentrated, vibrating load.

Common mistakes

Radiator discharge facing a wall 1 m away, causing summer high-temperature trips.
Exhaust outlet just above roof level, beside a stairwell window or an air-handling intake.
A fill point inside the building, reached by dragging a hose through a corridor.
Earth pits paved over and impossible to test.
Basement sets with no realistic way to bring a replacement set in or out.
Plinths built to “normal” height in a car park that floods every monsoon.

What to send us

Send the proposed set rating, a sketch of the location with dimensions, the building height, and photographs of the space, the access road and the proposed exhaust route. Our service engineers can carry out a site survey, mark out the clearances and fill in this checklist with you. Use the generator sales enquiry, or WhatsApp 98852 01608. We work across Telangana, Andhra Pradesh and every district within about 300 km of Hyderabad, with project support across India.

Questions engineers ask

How much space is needed around a generator?

As a minimum for a canopy set: 1.5 m on the control-panel and door side with full door swing, 1.0 m on the opposite side, 1.0 to 1.5 m at the intake, and 2 to 3 m clear in front of the radiator discharge unless it is ducted.

How far should a generator exhaust be from windows?

At least 3 m from any openable window, door or ventilation intake, measured from the outlet, at a height of at least H = h + 0.2 × √kVA metres, and discharging upward and away from the building.

How big should the ventilation openings be in a generator room?

As a starting point, an inlet of about 1.5 times the radiator core area and an outlet of about 1.25 times, placed so air sweeps across the set. Confirm against the maker’s cooling-air flow for your model.

Where should the fuel fill point be?

Outside the building, within the tanker’s hose reach (typically 15 to 30 m along the actual route), at a lockable fill box with spill containment, a visible level gauge and an overfill warning.

How far apart should earth pits be?

Electrodes should be spaced at least about twice their driven length apart, so about 6 m for 3 m electrodes. Keep neutral and body pits separate, clear of foundations and lightning electrodes, and accessible for testing.

How high should the generator plinth be?

At least 300 mm above the highest flood level recorded at the site, with a drainage fall away from the set. Fill points, vents and cable pits should also be above that level.

Can a generator be installed on a rooftop?

Yes, if the structural engineer confirms the slab for the set’s wet weight and dynamic load, suitable anti-vibration mounts are used, crane access is planned, and fuel supply and exhaust clearances work at that height.

Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer. Last updated 5 November 2026.