Sangamo Q551 Zone 4 Astro Time Switch 3 Pin 20A - Optional Early Off

The Sangamo Q551 is a Zone 4 astro time switch with a 3-pin 20A output, 24-hour programming and an optional early-off function. The unit automatically adjusts switching times throughout the year based on Zone 4 sunrise and sunset schedules (covering central England and Wales), eliminating the need to manually update on/off times as daylight hours change.

Designed for outdoor lighting control in street lighting, car parks, forecourts and building perimeter lighting, the Q551 switches loads up to 20A (4,600W at 230V). The optional early-off function allows the programmed off time to be advanced by a set number of hours, reducing energy consumption where full dawn-to-dusk operation is unnecessary. The 3-pin output suits standard contactors and relay coils used in lighting control panels.

The round-pattern dial face shows a 24-hour scale with red markings indicating switching periods. Three brass adjustment lugs on the dial set the on and off times, with the central nut tightened once programming is complete. A 100-hour battery reserve maintains the programmed schedule during mains power interruptions, preventing the need to reprogram after brief outages. The unit is rated for DIN rail or back-panel mounting inside control enclosures.

Product Specification Sheet

Product Manual

What is Zone 4 and does it cover my location?

Zone 4 covers central England and Wales, approximately from Birmingham to Manchester across to the Welsh coast. The astro function uses Zone 4 sunrise/sunset times to automatically adjust switching throughout the year. If your location falls outside Zone 4, a different zone time switch is required for accurate daylight tracking.

How does the optional early-off function work?

The early-off function allows the programmed dawn switch-off time to be advanced by a set number of hours, switching the load off earlier than the calculated sunrise time. This reduces energy consumption in applications where lighting is not needed until full daybreak.

What happens during a power cut?

The 100-hour battery reserve maintains the programmed schedule and real-time clock during mains interruptions. When power is restored, the time switch resumes normal operation without needing to be reprogrammed.

What is the 3-pin output used for?

The 3-pin output is designed to switch contactor coils or relay coils in lighting control panels, rather than switching the lighting load directly. The 20A rating refers to the contact capacity, which is suitable for most standard contactors.