Amogh N P
✦ In loving memory of Amogh N P — Architect · Designer · Visionary ✦
A high-rise lift lobby — a bank of elevators with floor indicators: vertical transportation, the service that makes the tall building possible.
Unit IIIBuilding Services for Special Buildings

Electrical & Vertical Transport

Powering the tower — and moving thousands of people up it.

≈ 45 min + studio task

A tall building is a vertical city, and its two great circulatory systems are electricity and the lift. Learn the electrical supply chain — from high-tension intake to every floor — and then the defining service of the special building: vertical transportation. Lift types, speeds and capacities, the traffic analysis that decides how many lifts a tower needs, and the zoning of lift banks and sky lobbies.

Learning objectives

By the end of this lesson, you will be able to — mapped to the course outcomes for Building Services for Special Buildings:

1
CO3 · Understand

Describe the electrical supply chain — HT/LT, substation, DG, distribution.

2
CO3 · Understand

Compare lift types, speeds and capacities.

3
CO3 · Apply

Apply traffic analysis and the zoning of lift banks.

4
CO6 · Apply

Locate the substation, DG, lift cores and lobbies in the plan.

Power and movement

Electrical & the lift

Power flows HT → substation → LT panel → risers → floor boards (with a standby DG); and the lift — traction for high-rise — is what makes the tall building possible.[2, 3]

HT to the socket HT intaketransformerLT panel risers → floor DBs standby DG
DiagramThe electrical supply chain — HT intake to transformer to LT panel to risers and floor boards, with a standby DG

HT to the socket

A large building takes a HIGH-TENSION (HT, 11/33 kV) supply into an indoor SUBSTATION, where a TRANSFORMER steps it down to low-tension 415 V three-phase. From the main LT panel, BUS RISERS carry power up the building to floor distribution boards and final circuits. STANDBY DIESEL GENERATORS (DG) carry the essential load — lifts, pumps, fire systems, life-safety — when the mains fail, and a UPS protects critical IT loads. EARTHING and LIGHTNING PROTECTION are mandatory for a tall building.[2]

Traffic & zoning

Vertical transportation

Traffic analysis (handling capacity, waiting time) decides the lift count; supertalls zone the lifts into banks with sky lobbies to save the core.[3]

How many lifts? Traffic analysis good officeresidential 12–15%5–7% handling capacity = % of population in 5 peak minutes too few → 9 a.m. jam · too many → wasted core · also: waiting interval (~25–30 s office)
DiagramLift traffic analysis — handling capacity as the % of population moved in the 5 peak minutes
Zone the lift banks (save the core) high bank (express) low bank sky lobby (transfer) one bank for every floor would fill the core with shafts
DiagramLifts zoned into low, mid and high-rise banks with a sky lobby transfer floor

How many lifts?

How many lifts a tower needs is decided by TRAFFIC ANALYSIS. The HANDLING CAPACITY is the percentage of the building's population a lift system can move in the 5 peak minutes — about 12–15% for a good office, 5–7% for residential. The INTERVAL or average WAITING TIME is the other measure — ~25–30 s for a prestige office, longer for a flat. Too few lifts and the lobby jams at 9 a.m.; too many and you waste valuable core area.[3]

The electrical & lift facts

At a glance

AspectOneThe other
SupplyHT intake → substation → transformer→ LT panel → risers → floor DBs
When mains failStandby DG: essential loadUPS: critical IT load
Lift typeTraction (rope): high-riseHydraulic: low-rise (≤ ~6 stops)
Traffic measuresHandling capacity: % in 5 minInterval: average waiting time
Serving a supertallZone into low/mid/high banksSky lobbies + double-deck cars
Vocabulary

Key terms

HT / LT supply

High-tension (11/33 kV) intake stepped down by a transformer to low-tension 415 V.

Substation / transformer

The indoor room and transformer that bring utility power into the building.

Standby DG

Diesel generator carrying the essential load (lifts, pumps, fire) when the mains fail.

Traction lift

A rope-and-counterweight lift — the type used for high-rise (geared or gearless).

Handling capacity

The % of a building's population a lift system moves in the 5 peak minutes (~12–15% office).

Interval / waiting time

The average wait for a lift — ~25–30 s for a prestige office.

Lift zoning / sky lobby

Grouping lifts into low/mid/high banks, with transfer floors in supertalls, to save core area.

Escalator

A moving stair at a 30° incline (max 35°) for high continuous flow over short rises.

Apply it

Studio task

For a 40-storey office tower, sketch a vertical-transport strategy — how many lift banks, which floors each serves, and whether you need a sky lobby — and mark the substation, DG room and lift cores in a typical-floor plan.

Check your understanding

Self-assessment

1. When the mains fail, the essential load of a high-rise (lifts, pumps, fire systems) is carried by —

2. A lift system's 'handling capacity' is —

3. A supertall tower zones its lifts into low/mid/high banks (and adds sky lobbies) mainly to —

In a nutshell

Recap

Power flows HT intake → substation/transformer → LT panel → risers → floor boards, with a standby DG for the essential load.
The lift makes the tall building possible: traction for high-rise, hydraulic for low; speed and capacity shape the core.
Traffic analysis (handling capacity ~12–15% office, and waiting time) decides how many lifts a tower needs.
Supertalls zone lifts into low/mid/high banks with sky lobbies and double-deck cars to save core area; escalators move short-rise crowds.
The evidence

References & further reading

  1. [2]National Building Code of India 2016, Part 8 Section 2 — Electrical and Allied Installations. BIS.
  2. [3]IS 14665 — Electric Traction Lifts; and NBC 2016 Part 8 Section 5 — Installation of Lifts and Escalators. BIS. https://law.resource.org/pub/in/bis/S05/is.14665.1.2000.pdf

Further reading

  • IS 14665 — Electric Traction Lifts. BIS.
  • Gina Barney, Elevator Traffic Handbook. Routledge.
  • NBC 2016 Part 8 — Building Services. BIS.

Sources gathered and fact-checked June 2026. Published values vary by source, sample and method — treat as indicative and confirm against the cited standard before structural use.