Sangamo Q551 Astro Zone 3 Time Switch - 24 Hour 20A 3 Pin

The Sangamo Q551 is a Zone 3 astro time switch with a circular dial, 24-hour programming, 20A switching capacity and a 3-pin output. The unit automatically adjusts switching times throughout the year based on sunset and sunrise calculations for UK Zone 3 geographical areas, removing the need for manual seasonal reprogramming.

Designed for controlling outdoor lighting, signage and heating systems in commercial and residential installations across central England and Wales (Zone 3 coverage), the Q551 mounts on standard DIN rail or surface-fixes via screw terminals on the rear casing. The 20A rating handles total loads up to 4,600W on 230V mains, allowing control of multiple circuits through a single switch. The optional early-off function allows loads to be switched off before sunset when daylight levels remain adequate.

The 100-hour battery reserve maintains programmed settings and continues switching operations during short-term power outages without requiring reprogramming. The round dial provides a visual reference for current time position and programmed on/off points, marked in red on the white face. The clear polycarbonate cover protects the dial from dust and accidental adjustment once settings are confirmed.

Product Specification Sheet

Product Manual

What is Zone 3 coverage?

Zone 3 covers central England and Wales in the UK astro time switch zoning system. The Q551 uses sunrise and sunset times calculated for this geographical area. If your installation is in a different zone, a corresponding Zone 1, 2, 4 or 5 variant is required for accurate seasonal adjustment.

How does the optional early-off function work?

The early-off setting allows the switch to turn off controlled loads before the calculated sunset time, useful when daylight levels remain adequate for longer than astronomical sunset during summer months. This reduces energy consumption while maintaining adequate light levels.

What happens during a power cut?

The 100-hour battery reserve maintains programmed settings and continues switching operations during mains power failure. If power is restored within 100 hours, the switch resumes normal operation without requiring reprogramming.

What is the maximum load?

The 20A rating handles total loads up to 4,600W on 230V mains. For LED lighting this translates to significantly higher fixture counts than with older halogen or incandescent systems due to lower per-fixture wattage.