277 V or 480 V: which North American supply

Key parameters

Power	100–240 W
Luminous flux	13,000–31,000 lm
Mounting height	6–10 m
IP rating	IP65
Input voltage	120–277 V single phase / 480 V three phase
Frequency	60 Hz
Allowed voltage drop	≤ 3% end to end

Product family: High Bay Lights

Voltage is the item most often skipped

This page is 120–277 V single phase / 480 V three phase at 60 Hz. Wide-range input is not about "works anywhere" — it is about not derating or tripping when the supply sits low or high. In regions with unstable grids, narrow-range drivers fail noticeably more often.

The other thing that gets skipped is inrush: when high-power fixtures start together the inrush adds up and trips the breaker. Where twenty units switch on at once, size the breaker on the row, not on one fixture — undersize it and the symptom is "it trips the moment you switch on", which few people trace back to the lights.

Voltage drop: right voltage, still dim

Allowed drop on this page is ≤ 3% end to end. It shows up worst on low-voltage and DC systems: a 24 V run of 30 m on 2.5 mm² can lose more than 10% by the far end, the fixtures visibly dimmer and the furthest ones dimmest. On site that looks like a faulty fixture; it is an undersized cable.

On the AC side the working figure is to keep total drop under 3%. That is a wiring parameter, not a fixture parameter — but it decides what the customer sees, so size the cable during the quote, not during commissioning when the lights get blamed.

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.