In short. A generator rental enquiry should state where and when power is needed, for how long, why, and what it must run. Include the running load and largest motor, voltage and phase, daily operating hours, where the set will connect, who supplies cables and fuel, site access and what happens if power is interrupted. If the end date is uncertain, say so; duration is an engineering input as much as a billing one.
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Why rental enquiries need more than a kVA figure
A rental set must reach the site, connect safely, carry the real load including starts, and keep running for the whole hire. Each of those depends on information that a kVA figure does not carry. The same 250 kVA set may be right for a planned shutdown of a commercial building and wrong for a construction site with a tower crane, because the crane’s starting demand and the changing site layout drive a different arrangement. Describing the requirement lets the proposal cover the complete temporary system, not just the machine.
What to tell us
| Item | What to describe | Why it matters |
|---|---|---|
| Reason for hire | Planned outage, failure, bridging, construction, event | Sets urgency, duration and transfer method |
| Dates | Power required from, expected end, chance of extension | Availability and fuel and maintenance planning |
| Load | Running kW or list of equipment, largest motor and starter | Rating and starting capacity |
| Voltage and phase | 415 V three-phase or 230 V single-phase | Set selection and connection |
| Operating hours | Continuous, day only, outage only | Fuel, operator and service needs |
| Connection point | Busbar, panel, changeover, distance from set | Cable size, length and termination |
| Fuel | Who supplies, how often, storage on site | Runtime and reserve |
| Consequence of interruption | Inconvenience, production loss, safety | Whether a standby second set is justified |
Duration, extension and fuel
State the dates explicitly and say whether an extension is likely. Many bridging and construction hires run well past their original end date, and a plan made for two weeks may not suit three months, particularly for fuel, servicing and cable protection. Fuel is the item most often left vague.
Daily fuel (L) = consumption at expected load (L/h) x daily running hours
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.
Consumption comes from the set’s fuel curve at the load it will carry, and daily running hours from the site’s operating pattern. Worked example (illustrative): a 125 kVA set carrying about 70 kW may use around 19 to 20 L/h. Running 16 hours a day, that is about 310 litres a day, so a 300 litre base tank will not last a day and refuelling or an external tank must be planned. The fuel runtime calculator repeats this with your figures.
Connection, protection and site access
Tell us where the temporary supply will connect and send photographs. A busbar that looks suitable on a drawing may be impractical if heavy cables cannot be routed to it safely. Moving a site from DISCOM transformer supply to a generator reduces available fault current, so the existing protection may need review. Where the site will switch between grid and rental supply, an interlocked changeover or ATS is needed so the set cannot back-feed the network; see rental ATS. Check that a truck or crane can reach the placement area, that the ground is firm and above monsoon water, and that exhaust will discharge away from occupied spaces. Accessories such as cables and distribution panels are covered under rental cables.
Earthing and safety on a temporary site
A rental set needs a tested earth for its frame and, where it is the source, for its neutral, arranged consistently with the site’s existing earthing so that earth-fault protection still operates. Earth electrodes for a long hire should be tested before energising and again if the set is moved. Cables crossing roads or work areas need mechanical protection, and distribution boards on construction sites need residual current protection for hand-held tools. Tell us whether the site has an existing earth grid near the placement area, because it affects what we bring.
What happens after you send it
We review the load and site details, ask for anything that would change the rating or connection, and propose a set with the cables, distribution, earthing, fuel arrangement and service during the hire. The proposal states what the site provides and what the rental includes. Sending an enquiry does not reserve equipment; availability and mobilisation are confirmed for the actual dates in writing. For planned shutdowns, enquire early so the transfer sequence can be agreed with the site team; see planned-outage power.
Common mistakes
- Requesting the size of the permanent set; a far larger rental set runs lightly loaded and burns more fuel per kWh.
- Not mentioning a large motor; the set cannot start it and the shutdown overruns.
- Assuming the rental includes cables and connection; on the day the set arrives with nothing to connect it.
- Giving a fixed end date when it is uncertain; the set is booked elsewhere when the extension is needed.
What to send us
Send the site location, dates and expected duration, the reason for the hire, running load and largest motor nameplate, voltage and phase, daily hours, photographs of the connection point and the placement area, and your fuel arrangement. For urgent breakdowns, call or WhatsApp 098852 01608 as well. Or contact Reddy Generators through the form and attach the photographs.
Questions engineers ask
What is the minimum rental period?
Minimum terms depend on the size of the set and the location, because transport and installation are a large part of the cost for short hires. The current terms are stated in the quotation.
Can a rental set connect to my existing AMF panel?
Often yes, if the panel and cable terminations are suitable. Send a photograph of the panel and its rating so we can check.
Do you provide an operator?
Operator support can be included where the hire needs it, such as continuous running or critical loads. State your requirement in the enquiry.
What if the rental set breaks down?
The rental agreement should state the response and replacement arrangement. For critical loads, discuss a second set or a standby arrangement before mobilising.
Technical content reviewed by Srinivas Reddy, Managing Partner, Reddy Generators. Last updated 19 October 2026.