We have been manufacturing our famous Round Pattern Time Switches in our Port Glasgow factory since 1951, having sold over 11 million units and counting, we often hear from customers who have had them installed, problem-free, for over 50 years or more.

A Sangamo time clock has many varied applications but the most popular include street, stairwell and security lighting, heating, ventilation and equipment control. Options in the range include 3 and 4 pin models and a ‘day omit’ device allowing you to turn your switch fully-off on selected days of the week.

There are four base models in our RPTS range:

S250 Standard

The basic ‘black dial’ time clock. The S250 range is our most straight forward dial and has no battery reserve. Each unit comes with either 2 or 3 on/off arms.

  • S254 | 3-pin, Day Omit function
  • S255 | 4-pin, Day Omit function

Q550 Standard

Our standard Q550 ‘red dial’ time clock. These units have a 100 hour battery reserve and come in a variety of arm and omit dial options.

  • Q554 | 3-pin, Day Omit function
  • Q555 | 4-pin, Day Omit function
  • Q557 | 4-pin, Day Omit OFF function (switch will stay on)
  • Q559 | 4-pin, Day Omit function, Early OFF on a selected day
  • Q563 | 4-pin, Changeover – 10/20A, Day Omit function on one circuit only
  • Q586 | 4-pin, Day Omit function, Early ON on a selected day

Q550 Solar

Each model in the Q550 Solar range comes in four different ‘solar zone’ versions, these are adjusted slightly to allow for the difference in sunrise/sunset times across the British Isles. In most cases your local wholesaler will only stock the zone in which they are located. All switches in this range are available as a 1on/off meaning the switch will operate fixed to sunset/sunrise times. The Q551 & Q553 are also available as 2on/off, which gives an extra set of on & off arms.

  • Q550 | 3-pin, Day Omit function, Early OFF selectable
  • Q551 | 3-pin, early OFF & ON selectable
  • Q553 | 4-pin, early OFF & ON selectable

E850 Digital

Our digital RPTS E850 range, perfect for those who want the reliability of a Sangamo time clock with the adaptability of electronic programming.  Comes in two models, both have a 50 day battery reserve and up to 96 operations per day.

How to choose the right switch

Black or Red?

The standard mechanical switches come in two varieties: black (S250) and red (Q550) dials. The two function identically except for switches with a red dial feature a 100 hour battery back up that keeps the dial turning should there be a loss of power. The equipment it is controlling will obvioulsy not switch with the lack of power but the time will remain correct and won’t need to be reset once power is restored to the circuit. All Solar dials we currently offer have a battery back up, as do the digital E850 models.

3-pin or 4pin?

the number of connection pins on the rear of the unit can either be 3 or 4. For a replacement model there is no way on the front of an installed unit to tell which type you have if you do not already know. For new installations the majority of cases will require a 3-pin time clock. Reasons for choosing a 4 pin include being able to isolate the switching circuit and for switching a circuit that isn’t 230v.

Day Omit function?

The Day Omit disc is the black circle behind the top of the dial with small white circles round the edge. This disc has the days of the week and, in its standard function, allows you to select days where the ON operation pins do not function (for example, you could select Saturday and Sunday on the disc and the switch would only operate Monday to Friday without stopping the clock turning).

The Q557 has a Day Omit OFF function, this is the opposite affect, the OFF operation is missed leaving the switch on until the next day, a less common requirement but specially designed for industrial purposes.

The Q559 features an “Early OFF” which means that one one day of the week the switch can go off earlier.

Conversely, the Q586 has an “Early ON” meaning that on one day of the week the switch can come on earlier.


If you have any questions about our RPTS range or are unsure which time clock is right for you, give us a call on 01475 745 131 and we can help find the perfect Round Pattern Time Switch for you.

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