Which type of lighting requires a specific ampacity to load ratio for a contactor?

High-intensity discharge (HID) lighting systems require a specific ampacity to load ratio for a contactor because of the unique electrical characteristics they possess. HID lights, which include types like metal halide and high-pressure sodium lamps, typically have a significant inrush current when they are powered on. This inrush current can be several times higher than their normal operating current, and it lasts only for a brief period as the lamp starts to generate light.

A contactor must be appropriately rated to handle this initial inrush current without being damaged or operating inefficiently. If the contactor's ampacity is not aligned with the load characteristics of the HID lights, it may lead to premature failure or unreliable operation. The specific ampacity to load ratio ensures that the contactor can manage this high inrush current as well as the continuous load, ensuring safe and reliable operation of the lighting system.

In contrast, other lighting types such as incandescent, LED, and fluorescent typically do not have the same level of inrush current, which reduces the necessity for strict ampacity requirements in their contactors. This distinction highlights why HID lighting is particularly sensitive to the ampacity to load ratio for contactors.