High-Intensity Discharge, the family of lamps that pass an arc through vaporized metals in a small arc tube: mercury vapor, metal halide and high-pressure sodium. They gave high output and long life for streets, stadiums, warehouses and stage followspots, but need a ballast, take minutes to warm up and cannot restart immediately after a power blip while hot. LED retrofits of HID fixtures are among the most common lighting energy projects.
Gym runs metal halide HID, so after that outage it'll be ten minutes of darkness before they restrike.
Also heard as
- high-intensity discharge
Related terms
Strike
To start the arc in a discharge lamp; restrike is relighting it after it has gone out.
Ballast
The device that starts and limits current to fluorescent and HID lamps, which would otherwise draw unlimited current.
Lamp
The trade word for a replaceable light source, what consumers call a bulb, as distinct from the fixture it goes in.
Stroboscopic effect
The way moving or rotating objects look stopped, slowed or multiplied under light that flickers.