20W Tri-Proof Lights

Key parameters

Power	20 W
Efficacy	130 lm/W
Luminous flux	2,600 lm
Maintained flux	1,820 lm
Mounting height	2.5–3.5 m
Coverage per fixture	6–8 m²
Design illuminance	200–300 lx
HID equivalent	1 × 36 W

Product family: Tri-Proof Lights

What the wattage figure does not tell you

At 130 lm/W, 20 W gives about 2,600 lm at the fixture; applying a 0.7 maintenance factor, roughly 1,820 lm reaches the floor at end of life. Layout counts come from 1,820 lm, not from the nameplate 20 W — layout by wattage and the far row always ends up dim.

A second double count: the 130 lm/W figure already includes driver losses. Discounting again by driver efficiency deducts the same loss twice and over-counts fixtures.

The height and area it actually covers

At 2.5–3.5 m and a design illuminance of 200–300 lx, one 20 W fixture covers about 6–8 m². That range is back-calculated from the maintained 1,820 lm, not the initial output — lay out on initial lumens and the site is under-lit well before the first relamping cycle.

If the existing HID is 1 × 36 W, 20 W lands in the same bracket: comparable flux, roughly a third of the power draw, and the circuit and switchgear usually carry over. What to re-check is inrush current and the earth-leakage setting.

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.