Sangamo Astro Zone 1 4-Pin Time Switch 1 On/Off Optional Early Off - 20A

The Sangamo Astro Zone 1 is a 4-pin astronomical time switch with a 20A rating, designed to control lighting and heating circuits based on sunrise and sunset times for Zone 1 geographical locations. The unit programmes one on/off operation per 24-hour cycle, with an optional early-off function that allows the circuit to switch off before the scheduled sunset time if required.

Designed for installation in domestic and commercial consumer units, the time switch fits standard DIN rail mounting and automates control of outdoor lighting, security lighting, street lighting and heating circuits without requiring manual adjustment through the seasons. The astronomical function calculates sunrise and sunset times based on the Zone 1 latitude setting, which covers the UK and similar northern European latitudes. The 100-hour battery reserve maintains programming and timekeeping during mains power interruptions.

The mechanical dial face shows a 24-hour scale with red graduations, and the central nut adjusts the timing offset. Three brass terminal clips on the grey metal housing connect to the incoming supply and outgoing load circuit. The clear polycarbonate cover protects the mechanism and allows visual confirmation of the current programme position. The unit measures 104mm × 83mm × 134mm and weighs 425g, making it one of the larger electromechanical timers in the Sangamo range.

Product Specification Sheet

Product Manual

What is an astronomical time switch?

An astronomical time switch calculates sunrise and sunset times based on latitude and date, then switches circuits on and off relative to those times. This means outdoor lighting automatically adjusts through the year without manual reprogramming as daylight hours change with the seasons.

What is Zone 1?

Zone 1 refers to a latitude band covering the UK, Ireland and similar northern European locations between approximately 50-58 degrees north. Sangamo astronomical timers are calibrated for specific zones to ensure accurate sunrise/sunset calculation for the installation location.

What does the early-off function do?

The optional early-off function allows the time switch to turn the circuit off before the calculated sunset time. This is useful for security lighting that only needs to operate during the darkest hours rather than from dusk to dawn, reducing energy consumption.

What is the 100-hour battery reserve?

The internal battery maintains the time switch's programming and timekeeping for up to 100 hours during mains power cuts. This prevents the programme resetting to factory defaults after brief power interruptions, which would otherwise require reprogramming.