What’s up with purple street lights?

What causes street lights to turn purple and what is Manitoba Hydro doing about it?

This article was published in November 2022 and may be outdated.

A lot of people ask us about odd-coloured street lights. Some say they’re turning blue, some say purple — whatever colour they look like to you, there are some street lights in Manitoba that are no longer white.

What’s causing it

It’s a manufacturer defect called “delamination.” LED street lights use LED packages that produce either a blue or purple light — in this case, purple — and a yellowish phosphor coating on them converts that colour to white. When the phosphor coating comes off, or delaminates, it lets the blue light through.

Illustration of a good street light LED, and a bad one, where the phosphor coating has seperated from the LED chip allowing purple light to escape.

  1. LED chip
  2. Phosphor coating
  3. Delaminated phosphor coating allowing purple light to escape

These defective lights emit the same amount of light, just in a different colour. There are no safety concerns with this spectrum of light.

What we’re doing

We’ve replaced over 1,000 purple street lights since we first noticed this problem. As more customers report them using our street light outage form, we continue to replace them as soon as our time, resources, materials, and staffing allow.

Since the lights are under warranty and the delamination is a manufacturer defect, the new lights are being replaced free of charge.

We’re not alone

These defective lights were part of a series of lights sold to multiple utilities all over the world. There are reports of purple street lights in Vancouver, several US states, and even in the UK.