Sangamo Astro Zone 1 4-Pin Time Switch 20A - 2 On/Off Operations

The Sangamo Astro Zone 1 is a 4-pin programmable time switch that automates lighting and heating loads up to 20A based on astronomical sunrise and sunset times for UK Zone 1 locations. It provides two independent on/off operations per 24-hour cycle, allowing control of circuits such as exterior security lighting, car park lighting, signage illumination, and display window lighting that need to switch on at dusk and off at dawn.

Designed for commercial, industrial and residential installation, the time switch calculates sunrise and sunset times for each day of the year based on pre-programmed latitude and longitude data for UK Zone 1. This removes the need to manually adjust switching times throughout the year as daylight hours change between winter and summer. The unit fits a standard DIN rail or surface-mount back box and connects via four terminals to the load and mains supply.

The 100-hour battery reserve maintains programmed settings during mains power outages, preventing the need to reprogram the unit after temporary supply interruptions. The clear dial face shows the current time position and the two programmed switching points via adjustable pins. Dimensions are 104mm high, 83mm wide and 134mm deep, with a net weight of 423g giving the unit sufficient mass to resist vibration in plant room installations.

The 20A rating handles resistive loads up to 4,600W on UK 230V mains, covering most commercial lighting circuits, electric heating elements and motorised gate controls. Inductive loads such as fluorescent ballasts and transformers should be derated to 50-60% of the resistive rating depending on power factor.

Product Specification Sheet

Product Manual

What is UK Zone 1 and does it cover my location?

UK Zone 1 covers southern England and Wales. The pre-programmed latitude and longitude data calculates sunrise and sunset times for this region. For locations in northern England, Scotland or Ireland, a different zone model is required.

How are the switching times set?

The unit uses adjustable pins on a 24-hour dial face. Each pin represents one switching operation. Position the pins at the offset from sunrise or sunset that you require — for example, 30 minutes after sunset for an 'on' operation, and 30 minutes before sunrise for an 'off' operation.

What happens during a power cut?

The 100-hour battery reserve maintains the clock and programmed settings during mains outages up to approximately four days. When mains power returns, the unit resumes normal operation without needing to be reprogrammed.

Can it switch inductive loads like transformers?

Yes, but the 20A resistive rating must be derated for inductive loads. As a guide, derate to 10-12A for fluorescent ballasts and low-voltage lighting transformers. Consult the manual or contact a qualified electrician to confirm suitability for your specific load.