Step 1 · Build a real connected-load list
Start with the actual equipment scheduled to run at the same time — welding sets, mixers, tower cranes, hoists, MEP tools, site-office HVAC and night-shift lighting. Nameplate ratings (kW) are the starting point, but the running load is what dictates capacity.
For a mid-rise superstructure site in Pune, this usually means separate lists for the day-shift civil crew and the night-shift MEP crew — the two rarely peak together, so the same DG set can serve both if the list is honest about simultaneity.
Step 2 · Add starting current for inductive loads
Motors, welding sets and compressors draw a heavy inrush at start-up — typically several times the running current. A rental sizing that only considers running kW will trip on the first crane hoist or the first welding strike.
This is the single most common under-sizing mistake on Pune construction sites. Share the largest motor / welder rating during quotation so the correct capacity margin is factored in.
Step 3 · Match KVA to your phasing plan
Foundation stage — small mixers, welding, night lighting — usually fits inside the 30–62.5 KVA band. Superstructure stage — cranes, hoists, MEP fit-out and site office — pushes demand into the 160–250 KVA band. Full commissioning and grid-changeover windows are where 320–500 KVA units come in.
Rather than renting one large set for the whole project, most Pune sites save on fuel by right-sizing per phase. A written quotation should include an equipment-swap plan across phases if the project duration is long.
Step 4 · Confirm site access and cabling
A DG set that fits the load but can't reach the site is useless. Check truck access, turning radius, cable-run distance to the LT panel and whether the site needs a silent canopy (guest-facing, hospital-adjacent, residential-adjacent). All three feed into the delivery window.
Safety note before you sign
The steps above are a starting point, not a final specification. Final generator sizing depends on the actual connected load, starting current, load type and site conditions on the day — including grid quality and cable losses. Confirm the final rating with a professional requirement assessment before you sign the rental agreement.