Powering a warehouse: the backup power guide for logistics operators

A generator on rent for a warehouse is sized by its motors, not its floor area: typical logistics configurations run 62.5–125 kVA for sortation hubs, 125–250 kVA for regional fulfilment centres, and 250–500 kVA for cold-chain sites. The reason is starting current — a conveyor motor started direct-on-line briefly draws about seven times its full-load current. Here is what to back up, how the rating is actually decided, and what a warehouse park will demand of the set once it lands.

TL;DR

• Back up what stops the dock: conveyors and sortation, dock levellers, high-bay lighting, scanners and WMS, MHE charging — and any electric fire pump
• Motor starting decides the rating: DOL ~7× full-load current, star-delta ~3×, soft starter ~3–3.5×, VFD ~1.1–1.5×
• Typical configurations, not formulas: sortation hubs 62.5–125 kVA, fulfilment centres 125–250 kVA, cold-chain sites 250–500 kVA — indicative bands
• There is no honest kVA-per-square-foot rule — build a load list and run the calculator
• Compliance lands with the set: the stack must clear the roof (H = h + 0.2√kVA) and noise is judged at your boundary, with limits dropping at night
• Short site leases and growing sort volumes are the structural case for renting over buying

What actually needs backup in a warehouse

A warehouse outage is not one failure — it is a sequence. Sortation stops, so parcels queue. Dock levellers freeze, so trucks wait at the bays. Scanners drop off the WMS, so whatever does move goes unrecorded. Our logistics clients put it plainly: a dark dock is a missed cutoff, and every outage minute becomes a linehaul delay somewhere downstream.

So the load list starts with whatever stops throughput:

One decision shapes everything after it: full-site backup or an essential panel? Backing up the whole incomer is simple and expensive. Many sites split the switchboard instead — sortation, docks, lighting and IT on the generator; comfort HVAC shed during outages. Every load you shed is kVA you do not rent. But the split has to exist in copper and breakers, not in intent — an “essential panel” that was never actually segregated backs up nothing.

Why warehouse loads are surge-driven

A warehouse’s electrical profile is motor-heavy, and motors punish lazy sizing. An induction motor started direct-on-line (DOL) draws about seven times its full-load current for the seconds it takes to run up. The alternator must absorb that surge without the voltage dipping far enough to drop contactors across the site. The starter fitted to each motor sets the multiple:

Three consequences follow for warehouses specifically:

1. The largest simultaneous start governs. If every conveyor bank restarts together when power returns, the alternator must swallow the whole surge at once. Stage the restarts — bank by bank, seconds apart — and the required rating drops. Ask your controls vendor whether the restart sequence is staged before you ask any generator vendor for a price.
2. A starter can be cheaper than a rating step. Two hubs with identical running loads can need sets two ratings apart purely because one starts its biggest motor DOL and the other fitted a star-delta or soft starter. Run that arithmetic before accepting the bigger set.
3. Charging bays behave like UPS rooms. A wall of MHE chargers is a non-linear load. At small scale it is noise; at scale, harmonics heat the alternator, and the honest fix is an oversized or specially-wound alternator rather than more engine. Flag it in the enquiry.

So what size generator does a warehouse need?

There is no honest kVA-per-square-foot rule, and you should distrust anyone quoting one. Two identical 100,000 sq ft boxes can need completely different sets: one is dry storage with LED high-bays and a handful of dock doors; the other runs a full sortation loop, thirty dock levellers and a cold room. The building is the same. The load is not.

What we can publish is the typical-configuration table from our logistics sector page — indicative, always confirmed against the actual load list:

In dense godown belts the numbers sit lower: across Bhiwandi, most godowns run 40–82.5 kVA — dock levellers, conveyors and high-bay lighting — with dark stores at the smaller end.

Bands bracket the answer; only a load list decides it. The method is four steps. Sum your loads in kW and divide by 0.8 to get running kVA. Size so that load sits at roughly 70–80% of the set’s prime rating. Check that your largest simultaneous motor start can be absorbed — in a warehouse this check usually wins. Then check the other direction: below about 30% sustained loading a diesel set risks wet stacking, so too big is also wrong. The sizing guide walks the full arithmetic — its worked example is literally a 30,000 sq ft warehouse whose DOL compressor pushed the answer from 45 kVA to 100 kVA — and the kVA calculator runs the same method on your equipment list in a minute.

Siting and compliance in a warehouse park

The set that arrives on a truck brings three compliance surfaces with it.

The exhaust stack must clear the roof. The CPCB minimum is H = h + 0.2 × √kVA, where h is the height of the building the set stands beside — and warehouse eaves are tall. A 125 kVA set beside a 10 m building needs a 12.24 m stack. Where the set stands changes the arithmetic: a ground-mounted position in the open yard is a different h than a position against the warehouse wall. Get the siting decision and the stack quote made together, and read the stack height guide before the crane arrives.

Noise is judged twice. The canopy is certified at the factory — 75 dB(A) at 1 m for sets up to 1000 kVA manufactured on or after 1 January 2005 — but your neighbours complain under a different law: the ambient noise limits at your boundary, which drop at night in every zone. Night is exactly when sortation peaks. Distance to the boundary and the direction the set faces are the cheapest decibels you will ever buy; the noise norms guide covers both tests and the zone-wise numbers.

The consent writes your site’s rules. Stack height and noise become binding through the consent conditions issued by your State Pollution Control Board or Pollution Control Committee, and site-specific conditions can be stricter than any formula minimum. In a managed warehouse park, the lease often adds its own layer: designated DG yards, shared boundaries, refuelling rules. Read both documents before the set is positioned. The practical siting checklist is short: firm, level standing; radiator discharge not blowing into a wall; a sane cable run to the LT panel; refuelling access; and a position outside the truck circulation path.

Rent or buy: the timing question for 3PLs

For a 3PL, the rent-or-buy question is structural before it is financial. Four arguments, then the honest boundary.

The asset outlives the tenancy. A warehouse posting is a contract term; a genset is a long-lived machine. When the client contract ends and the site is handed back, an owned set becomes a relocation project — transport, a new stack height at the next building, fresh consent conditions in a possibly different state. A rented set gets picked up.

The rating stays a variable. Sort volumes grow, clients change, a dark store becomes a hub. On rental, the rating moves with the load — Rivigo’s 20 kVA Bhiwandi set was upgraded mid-contract exactly that way when its load grew. An owned set makes today’s sizing guess permanent.

The compliance trajectory sits with the vendor. Emission norms for new gensets moved to CPCB IV+, and an owned set carries its norm era on its own books for life. On rental, keeping the fleet current is the vendor’s problem, not a line in your asset register.

Service scales across a network. The structure our logistics clients run on is one master agreement, per-hub work orders, consolidated billing and the same service terms at every site: scheduled B-checks every 250–300 running hours, a 4–6 hour breakdown SLA, and — on newer work orders — a standby clause: if a rental is down beyond 24 hours, a standby set arrives at our cost. In cities where the fleet is already deployed, a new hub is typically 24–72 hours from work order to a commissioned set.

The honest boundary: if you own the building, the load is steady and the horizon is a decade, buying can win — that is a different decision with its own page. For a 3PL holding short site leases against growing volumes, the structure argues for rental before any spreadsheet does.

What this looks like on the ground

The Bhiwandi warehouse belt is where this playbook runs daily. XpressBees has run sets at Mankoli and Saidhara — 15, 40 and 50 kVA units with field service reports on file — alongside 10 and 35 kVA sets in the same belt. YCH Logistics ran 62.5 and 82.5 kVA sets at Mankoli and Padgha, 20 Cube Logistics ran a 62.5 kVA set on the Padgha–Kalyan Road side, and an Asus Technology 30 kVA rental at Kalher–Kasheli generated service reports from 2019 right through 2023–24 — that is what long-term looks like.

At network scale, logistics is our largest segment: rental sets deployed across hubs in 15+ cities for a single network — Busybees Logistics (Xpressbees) — with one contract, one SLA and one number to call, and Rivigo, YCH Logistics India, 20 Cube Logistics and ProConnect Supply Chain Solutions on the same sector roster. The sector offer lives on the logistics & warehousing page; the belt-level deployment record on the Bhiwandi page.

Getting the number right

Build the load list — every motor with its starting method, the lighting, the chargers, the IT — and run it through the kVA calculator. Then send the result and your equipment list to an engineer on WhatsApp: sizing confirmation is free, same-day, and can move an enquiry a rating step in either direction before any money moves.

Sources: starting-current multiples and the sizing method are per Stamford AGN090 “Motor Starting Fundamentals” and ISO 8528 rating conventions, as applied in this site’s sizing guide and kVA calculator. Stack height: CPCB Environmental Standards §22.0 / Emission Regulations Part IV [COINDS/26/1986-87], made binding by Note 6 of G.S.R. 771(E) of 11 December 2013. Noise: G.S.R. 371(E) of 17 May 2002 as amended, and the Noise Pollution (Regulation and Control) Rules, 2000 — both covered in full in the linked compliance guides. Typical-configuration bands, client deployments and rental service terms are Power Solutions’ published records on this site’s industry and location pages. Final sizing is always confirmed against the actual load list.