Factory hall 55.75 m × 40.25 m LED lighting

Given: hall 55.75 m × 40.25 m, E = 250 lux (lm/m²), 30 W LED panel at 100 lm/W, UF = 0.8, MF = 0.6, supply 400 V, 3-phase, 4-wire. Assumptions: mounting height 3 m above the working plane, maximum spacing-to-height ratio 1.5, LED driver pf 0.9.

Number of luminaires

Lumen method: N = (E × A) / (φ × UF × MF), where φ is the output of one luminaire.

Area A        = 55.75 × 40.25 = 2243.938 m²
φ per luminaire = 30 W × 100 lm/W = 3000 lm
Total lumens  = E × A / (UF × MF)
              = 250 × 2243.938 / (0.8 × 0.6)
              = 1168717 lm
N             = 1168717 / 3000 = 389.57

Rounding up and fitting a regular grid: 26 × 15 = 390 luminaires (26 along the 55.75 m side, 15 along the 40.25 m side).

Arrangement and spacing

Spacing along length = 55.75/26 = 2.14 m
Spacing along width  = 40.25/15 = 2.68 m
End spacing (to wall) = half of these
Max spacing = SHR × Hm = 1.5 × 3 = 4.5 m
2.14 m and 2.68 m ≤ 4.5 m  → OK
Actual E = 390 × 3000 × 0.8 × 0.6 / 2243.938
         = 250.3 lux (≥ 250 lux required)

Layout diagram

Plan 55.75 m × 40.25 m (o = luminaire)
+---------------------------------------------+
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
|                      :                      |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
| o o o o o o o o o o ... o o o o o o o o o o |
+---------------------------------------------+
[DB]  [SB]  <- entrance: DB and switch board
       S S S S ... one switch per sub-circuit

Each light sub-circuit is controlled by one 6 A one-way switch; all switches are grouped on a switch board (SB) next to the entrance, and the DB is mounted beside it.

Sub-circuits

Rule (IS 732 / NEA practice): a light sub-circuit carries at most 10 points and 800 W. Here one luminaire is 30 W, so up to 10 luminaires per sub-circuit. Number of circuits is made a multiple of 3 for phase balance.

Largest light circuit: 300 W → I = 300/(230 × 0.9) = 1.45 A → 6 A MCB, 1.5 mm² Cu.

Distribution board design

Total connected load = 11700 W (lighting)
Most loaded phase    = 3900 W
Iph = 3900 / (230 × 0.9) = 18.84 A
Main MCB ≥ 1.25 × 18.84 = 23.55 A → 25 A TPN MCB

DB specification: 16-way-per-phase TPN DB (48 ways in all, spares included) with 25 A TPN MCB as incomer, 25 A 4-pole RCCB (100 mA) for earth-leakage protection, 6 A SP MCBs (B-curve) for light circuits. Incoming cable: 4-core 2.5 mm² Cu PVC (rating 27 A ≥ 25 A), plus earth continuity conductor.

3-phase, 400/230 V, 4-wire supply
        |
   [Energy meter]
        |
   [25 A TPN MCB]
        |
   [25 A 4P RCCB]
        |
==R====Y====B====N== busbars
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  L1   L2   L3   L4   L5  ...