Quick answer: A well-designed office electrical system sizes the incoming supply on diversified demand, splits circuits into raw (mains or DG-backed) power and UPS power, and sizes the DG set and UPS from the critical load, not the whole connected load. Indicative demand for a 10,000 sq ft office ranges from roughly 60–90 kVA where the landlord supplies chilled water to roughly 120–160 kVA where you run your own VRF, per figures published by one Indian MEP consultancy, so always confirm with a qualified electrical engineer.
What "office electrical design" actually covers
Office electrical design is the plan for how power reaches every desk, light, AC unit and server in your office, and how it keeps working when the grid does not. It includes load calculation, distribution boards and cabling, earthing, UPS and DG backup, lighting circuits, metering and safety protection.
In an interior fit-out, electrical design sits alongside HVAC, fire and IT cabling as part of the MEP (mechanical, electrical and plumbing) package. Getting it wrong is costly because changes after the ceiling and floor are finished mean opening up finished work. Our MEP works page explains how this is managed inside a design-and-build contract.
The three power tiers: normal, essential and UPS
Most Indian office buildings run three levels of supply:
- Normal (raw) power: grid supply from the DISCOM through the building transformer. It feeds general loads such as lighting, sockets and HVAC. It is lost in an outage.
- Essential (DG-backed) power: a diesel generator picks up designated loads after a short changeover delay of a few seconds to a minute.
- UPS power: battery-backed supply with no break, for computers, network equipment, servers and critical meeting-room systems. Runtime is usually short, typically 15–30 minutes, enough for a graceful shutdown or for the DG to start.
Raw power simply means power that is not conditioned or battery-backed by your own UPS. A common beginner's mistake is putting everything on UPS. That inflates UPS size and battery cost, and fills the room with heavy equipment for loads that can safely ride on DG.
Office electrical load per sq ft: how to estimate it
Area-based figures are only a first sanity check. Better practice is to build up the load by component. Indicative figures published by an Indian MEP consultancy suggest:
| Load | Indicative figure | Comment |
|---|---|---|
| Lighting (LED) | 0.7–1.2 W per sq ft | Depends on lux targets and fixture choice |
| Small power | 150–250 W per workstation; 400–800 W per meeting room | Counted per device, not per sq ft |
| Pantry appliances | 1.5–3 kW each | Often forgotten, and often on a separate circuit |
| HVAC: your own VRF/DX | 7–10 W per sq ft | Largest single load |
| HVAC: landlord chilled water | 1.5–2.5 W per sq ft | Only fan-coil or AHU power is on your side |
Treat this as indicative, not a design basis. For cross-checking lighting, the Energy Conservation Building Code (ECBC) 2017 sets 12 W/m² as the installed lighting power limit for compliant office spaces, which is about 1.1 W per sq ft, in line with the figure above.
Diversity: why you do not add everything up
Not every device runs at full load at the same time. Diversity factors of about 0.6–0.75 are commonly applied to non-HVAC loads, while HVAC is treated closer to 1.0 at summer peak. The rule that matters: size the incoming supply and DG on diversified demand, and size cables and protection on connected load.
The same source gives a sanity check for a 10,000 sq ft office: about 60–90 kVA demand with landlord chilled water, and about 120–160 kVA with your own VRF system. That doubling is why the HVAC route is the first electrical decision, and why our office HVAC design guide and this article should be read together.
UPS sizing for offices
Size the UPS for the critical load, not the whole office. A commonly used approach is to take about 25–40% of small-power load as critical, then add about 25% headroom.
Worked example: 100 workstations at 200 W each is 20 kW of small power. At 25–40% critical, that is 5–8 kW. Adding 25% headroom gives about 6.25–10 kW, or roughly 7–11 kVA at a power factor of 0.9. A dedicated server or network room should be calculated separately and usually needs its own UPS, cooling and monitoring. See the related guide on fit-out planning for CFOs for how these items fit the budget.
Decide early whether you want a centralised UPS or small rack-level or floor-level units. Centralised systems are easier to maintain, while distributed units reduce cabling length and single-point-of-failure risk.
DG backup: sizing and emissions
As a rule of thumb, DG capacity is about 1.25 times diversified demand, so the set is not running at its limit. In many multi-tenant buildings the landlord provides shared DG backup and allocates you a share, so check the allocated kVA and the changeover time before you finalise your design.
If you must install your own set, check current emission rules. One source notes that CPCB IV+ emission compliance is mandatory for DG sets up to 800 kW; confirm the current notification and any state-level restrictions, particularly in Delhi-NCR where air-quality measures can limit generator use.
Distribution, earthing and safety standards
The standards most often referenced in Indian office electrical design include:
- IS 732:2019 for wiring installations.
- IS 3043:2018 for earthing; measured earth-resistance values should be recorded at handover.
- SP 30:2023, the National Electrical Code.
- NBC Part 8 (building services) for electrical installations in buildings, with a revised NBC edition reported in circulation, so confirm the version your authority applies.
- Electricity Act, 2003 and the CEA safety regulations, which govern licensed contractors and statutory safety.
- ECBC 2017, applicable to commercial buildings with a connected load of 100 kW or more, or contract demand of 120 kVA or more. It requires lighting controls, power factor correction and sub-metering.
Good practice in the fit-out itself includes separate distribution boards for lighting, raw power, UPS power and HVAC; colour-coded sockets for UPS circuits; RCCB protection for socket circuits; labelled panels with single-line diagrams; and spare capacity for future seats. Cables specified for fire safety, such as fire-retardant low-smoke types, are commonly used in offices but should be confirmed against your fire consultant's requirements. For fire coordination, read our office fire safety guide and the fire-safety guidance in the building's own certificate.
Raw power vs UPS power: how to split your circuits
| Load | Raw / DG-backed | UPS |
|---|---|---|
| General lighting | Yes | Emergency or exit lights only, on dedicated backup |
| Workstation sockets (PCs, laptops, monitors) | No | Yes |
| Network switches, Wi-Fi, firewalls | No | Yes |
| Server or comms room | No | Yes, often dedicated UPS |
| Printers, copiers, pantry appliances | Yes | No, because of surge and heating loads |
| HVAC | Yes (DG-backed if essential) | No |
| Meeting-room AV and video-conferencing | Partly | Yes for codec and control systems |
Common mistakes in office electrical fit-outs
- Choosing the HVAC route after the electrical load is fixed.
- Putting printers and pantry equipment on UPS circuits.
- Ignoring the allocated load in the building's electrical sanction, then needing a load enhancement mid-project.
- No spare capacity in distribution boards for seat growth.
- Missing earth-pit records and test certificates at handover; see our handover checklist.
How electrical design affects fit-out cost and timeline
Electrical scope is one of the larger movers of a fit-out budget, along with shell condition, HVAC route, fire changes, furniture and AV/IT. Officea's 2026 rate card covers four tiers, per sq ft with GST extra:
| Tier | Officea 2026 rate | Typical profile |
|---|---|---|
| Basic | ₹1,800 per sq ft | Laminate workstations, vinyl or basic carpet tile, standard lighting |
| Medium | ₹2,200 per sq ft | Better laminates, branded carpet tile, task lighting |
| Good | ₹2,600 per sq ft | Premium carpet tile, glazed cabins, better AV in meeting rooms |
| High end | ₹4,500 per sq ft | Premium materials, bespoke joinery, statement lighting |
Timelines are heavily affected by MEP. As a reference from Officea's own projects, a 10,000 sq ft office in Noida with full MEP was delivered in 43 days, and a 3,000 sq ft office in Gurgaon in 28 days. Planning electrical early is how projects stay on schedule. For the full rate card, see office fit-out cost in India.
Getting it designed and delivered in one place
Officea Design & Build handles electrical design and installation inside a single design-and-build contract, so load calculations, DB layouts, UPS and DG coordination sit with the same team that builds the office. Offices in Delhi, Gurgaon, Noida and Bangalore support projects in every state in India. For a free site visit and a layout and budget estimate, send us your requirement.
Frequently asked questions
How many kVA does a 10,000 sq ft office need?
Indicative published figures are about 60–90 kVA with landlord chilled water and about 120–160 kVA with your own VRF system. These are planning numbers only. A qualified electrical engineer should calculate your actual demand.
What is the difference between raw power and UPS power in an office?
Raw power is mains or DG-backed supply without your own battery conditioning, and it suits lighting, HVAC and appliances. UPS power is battery-backed and uninterrupted, and it is meant for computers, network gear and servers.
How big should the UPS for an office be?
A common method takes 25–40% of small-power load as critical and adds about 25% headroom. For 100 workstations at 200 W, that works out to roughly 7–11 kVA, before any server room load.
Do I need my own DG set for a leased office?
Often not. Many buildings provide shared DG backup and allocate a share to each tenant. Check the allocated kVA, changeover time and charges before deciding to install your own.
Which standards apply to office wiring and earthing in India?
IS 732:2019 covers wiring and IS 3043:2018 covers earthing, alongside the National Electrical Code (SP 30:2023), NBC Part 8, the Electricity Act 2003 and CEA safety regulations. ECBC 2017 applies to larger commercial buildings.
Does ECBC apply to my office fit-out?
ECBC 2017 applies to buildings with a connected load of 100 kW or more, or a contract demand of 120 kVA or more. If you are in a covered building, expect requirements on lighting controls, power factor and sub-metering.
Sources
- https://www.beeindia.gov.in/WriteReadData/L45218/1734417634.pdf (ECBC 2017)
- https://blogs.airbrickinfra.com/office-electrical-load-planning-kva-ups-dg-india/ (vendor blog, indicative figures)
- https://www.studiomatrx.org/guides/building-electrical-services-guide-india (standards list)