Sangamo Astro Zone 4 24-Hour Timer Switch 20A 3-Pin - 1 On/Off Day Omit

The Sangamo Astro Zone 4 is a 24-hour programmable timer switch with a 20A current rating, designed to automate lighting and electrical circuits based on time-of-day schedules. The unit operates on a 3-pin connection and provides one on/off switching operation per 24-hour cycle, with a day omit function that allows specific days to be skipped from the programmed schedule.

Designed for commercial lighting control, street lighting, signage, security lighting and automated building services, the Zone 4 suits applications where circuits need to switch on at dusk and off at dawn, or at fixed times independent of daylight variation. The timer mounts into standard control panels and distribution boards via DIN rail or screw fixing, and the clear polycarbonate cover allows the dial position to be checked at a glance without opening the enclosure.

The mechanical dial uses a 24-hour scale marked with red numerals and tick marks at 15-minute intervals, giving programming precision to within a quarter-hour. Brass terminal clips secure the dial position once set, and a central locking nut prevents tampering after installation. The 100-hour battery reserve maintains the programmed time during mains power interruptions, so the timer resumes correct operation when power is restored without needing to be reset.

The day omit function operates as a skip mechanism: when activated, the timer bypasses the next scheduled on operation and remains off for that cycle. This is useful for reducing energy consumption on days when a building is unoccupied, or for temporarily disabling automated lighting without reprogramming the entire schedule. The unit measures 104mm length × 83mm width × 134mm height and weighs 424g, fitting typical enclosures rated for 20A switching loads.

Product Specification Sheet

Product Manual

What does the day omit function do?

Day omit acts as a skip mechanism. When activated, the timer bypasses the next scheduled on operation and remains off for that cycle. This allows temporary disabling of automated switching without reprogramming the entire schedule, useful for unoccupied buildings or maintenance periods.

How is the timer programmed?

The timer uses a mechanical 24-hour dial marked in 15-minute intervals. Brass clips are positioned on the dial to set the on and off times, and a central locking nut secures the dial once programmed. The clear polycarbonate cover allows the dial position to be checked without opening the enclosure.

What happens during a power cut?

The 100-hour battery reserve maintains the programmed time during mains power interruptions. When power is restored, the timer resumes correct operation without needing to be reset or reprogrammed.

What load can it switch?

The Zone 4 is rated at 20A, suitable for switching lighting circuits, signage, security lighting and other building services loads up to 4,600W at 230V. Always verify the total connected load does not exceed the 20A rating.