Sangamo Q551 Round Pattern Astro Zone 4 Time Switch - 3 Pin 20A

The Sangamo Q551 is a round pattern astro time switch calibrated for Zone 4, delivering automatic dawn-to-dusk switching for exterior lighting, security lighting and commercial perimeter installations. The unit programs 24-hour on/off operations based on calculated sunrise and sunset times for the geographic zone, eliminating manual seasonal adjustment of switching times.

Designed for wall-mounting in plant rooms, service cupboards and consumer units, the time switch operates on 230V mains with a 20A contact rating, handling loads up to 4,600W. The 3-pin terminal configuration accepts live, neutral and load connections, with the round housing fitting standard enclosures used in commercial and light industrial installations. The 100-hour battery reserve maintains programming and real-time clock operation through mains outages without requiring reprogramming.

The white dial face shows 24-hour time markings in red, with brass-finished programming clips that set the on/off switching points by rotating around the dial. The 'Made in UK' marking appears on the face along with the Zone 4 designation, which covers geographic areas requiring specific dawn/dusk calculations. The clear polycarbonate cover protects the dial and clips during operation while allowing visual confirmation of programming status.

Product Specification Sheet

Product Manual

What is Zone 4 and does it cover my location?

Zone 4 is a geographic calibration used by Sangamo for calculating sunrise and sunset times. Zone 4 typically covers parts of the UK and northern Europe. Check the product manual or contact us to confirm whether Zone 4 matches your installation location — installing a time switch calibrated for the wrong zone results in switching that occurs too early or too late relative to actual dawn and dusk.

How is the time switch programmed?

Programming uses the brass clips visible on the dial face. Rotate the clips to the desired on/off times on the 24-hour scale. The dial rotates continuously as the internal clock tracks real time, triggering the switching action when the dial position matches a clip position. The product manual includes detailed programming instructions.

What happens during a power cut?

The 100-hour battery reserve maintains the real-time clock and programming through mains outages. When mains power is restored, the time switch resumes normal operation without requiring reprogramming. If the battery depletes during an extended outage, the unit will need to be reprogrammed once mains power returns.

What load can it switch?

The 20A contact rating handles resistive loads up to 4,600W on 230V mains. For inductive loads such as fluorescent ballasts or motor-driven equipment, consult the specification sheet for derated capacity.