Choosing LED street light wattage by road width and pole height

Start from the lux target, not the wattage

IS 1944 groups roads by traffic: main roads need 20–30 lux, secondary and collector roads 10–15 lux, residential streets 5–10 lux. The fixture wattage then follows from road width, pole height and spacing.

Quick selection table (single-side poles, LED at 120 lm/W, maintenance factor 0.8)

Road width	Pole height	Spacing	Target lux	Suggested LED wattage
4–5 m lane or colony road	6 m	20–25 m	5–8	24–30 W
6–7 m residential street	7 m	25–30 m	8–10	36–50 W
7–8 m secondary road	8 m	30 m	10–15	60–80 W
9–10 m collector road	9 m	30–35 m	15–20	100–120 W
11–14 m main road (per side)	10–12 m	35–40 m	20–30	150–200 W
Highway or junction	12 m, staggered or opposite	40 m	30+	200–250 W

For roads wider than about 1.2 times the pole height, use opposite or staggered arrangements rather than a bigger single fixture.

Mounting rules of thumb

• Overhang: the fixture should sit 0.5–1 m over the carriageway; a long arm pushes light onto the road rather than the footpath.
• Tilt: keep the fixture within 0–10° tilt. Over-tilted luminaires glare drivers and waste light upwards.
• Spacing to height ratio: 3–3.5 for secondary roads, up to 4 with wide-distribution optics. Beyond that, uniformity fails.
• Optics: Type II for narrow roads, Type III for wider roads on single-side poles.

Common mistakes

1. Choosing by wattage and getting a fixture with poor optics, so the footpath is bright and the centre line dark.
2. Mixing 3000 K and 6500 K fixtures on one stretch.
3. Ignoring surge protection: rural feeders see 4–10 kV transients, which a 2 kV driver will not survive.
4. Forgetting the photocell or timer: dusk-to-dawn operation on a 12-hour night is where energy savings are won.

Use the bulk and customisation portal to enter your road width, pole height and spacing; it reports the average lux and uniformity for each HiLums and Oreli street light and recommends the closest match.