Area light distribution types I–V
Type I–V describes the shape of the pool: I is narrowest (walkways), II/III the most common (yards and roads), IV throws forward (keeps the wall behind dark), V is fully symmetric (round areas). The symptom of the wrong type is a bright spot under the fixture and dark corners, which more fixtures will not fix because the light never goes there.
Get a QuoteKey parameters
| Power | 100–300 W |
|---|---|
| Mounting height | 6–12 m |
| IP rating | IP66 |
| Beam angle | Varies by type (I narrowest, V symmetric) |
| Distribution type | IES Type I–V |
The distribution decides where the light goes
Two fixtures with the same wattage and the same flux can put a twofold different illuminance on the floor, purely because of distribution. This page is IES Type I–V. Distribution decides three things: the shape of the pool of light, how much of the flux reaches the floor, and whether the spacing can be opened up.
A common misjudgement is comparing distributions by centre illuminance. A narrow beam usually wins at the centre point and loses badly at the edges, giving a lower average. Compare average illuminance plus uniformity (minimum over average) — those two numbers match what people actually see.
Angle and height come as a pair
This page is Varies by type (I narrowest, V symmetric) at 6–12 m. The direction is unambiguous: the higher the ceiling, the narrower the optic, or the light lands on the walls; the lower the ceiling, the wider the optic, or the floor gets discrete bright spots and hard shadows under each fixture.
Rule of thumb: pool diameter ≈ 2 × height × tan(half angle). At 10 m, 90° gives about 20 m and 60° about 11.5 m. Sketch the layout with that first and ask for a photometric calculation second — the other order usually costs a revision.
Four things to verify before ordering
① Whether flux and efficacy are quoted for the complete fixture or the light source — a 10–15% difference that changes the fixture count. ② Whether colour temperature and CRI are measured or nominal values; mixed CCT within one batch is the most common arrival dispute. ③ Driver brand and model, plus its derating curve at high temperature — it is the only part that really sets life. ④ The mounting kit list: chain, bracket and anchors in the box, or the site stops for a day.
Concepts on this page
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