PE takes a closer look at Sangamo, the Port Glasgow-based company that has been manufacturing Round Pattern Time Switches (RPTS) for over 60 years.
With over 11 million units sold to date, the installation of a Sangamo Round Pattern Time Switch (RPTS) used to be a regular job for many electricians. Despite the electro-mechanical time switches being less common today, the company still report sales of thousands of units each month, both as replacements and as brand new installations. The same basic design of switch has been manufactured in Sangamo’s Port Glasgow factory since 1951. Many of their highly skilled workforce can claim over 30, or even 40, years of service.
Many installers still trust the Sangamo RPTS for a wide variety of applications, not just for its reliability but for its ease of use. The simple dial and levers make setting the switch up for daily ﬁxed timings a breeze with no complicated menu options to navigate through. All Round Pattern Time Switches are also 20 Amp rated, providing a more robust switch than most other products on the market.
“We regularly hear from people with Round Pattern Time Switches still going strong after 40 and 50 years.”
The switches are split into four categories each containing both three-pin and four-pin connections. Three-pin switches have common clock and switch connections. This means that the same 230V ac live supply used to run the clock is also used as the live input for the switching circuit. Four-pin switches have independent clock and switch connections which enable a different AC switching circuit voltage to be controlled from that of the 230V required to run the clock, for example to switch a 110V ac machine.
• S250 range – The standard ‘black dial’ 24-hour time switch with day omitting options to stop the switch functioning on selected days.
• Q550 Standard range – A 24-hour ‘red dial’ switch with added battery reserve to keep the switch in time if any power outage occurs. Available with a variety of day omit and early on and early off varieties as well as a 110V model and a 20A/10A SPDT Changeover time switch.
• Q550 Solar range – The much loved solar/astro time switch specially designed for lighting applications. A series of gears and cams move the on and off operations throughout the year to match sunrise and sunset times without need for a photo sensitive cell. Each model is available in four solar zones that allow for the slightly different sunrise/sunset times throughout out the UK.
• E850 Digital range (pictured) – the newest addition to the Round Pattern Time Switch range, the same trusted switch but with an intuitive digital LCD screen replacing the dial which allows for up to 96 operations per day and seven-day programming while keeping the 20A rating as its mechanical counterpart.
With 37 different models split across the four ranges, Sangamo offers a customer support line where their staff can assist installers in ﬁnding the right switch for each application.
Sangamo’s Managing Director, Mark Robinson, observes: “We regularly hear from people with Round Pattern Time Switches still going strong after 40 and 50 years. When they eventually need a new switch they reasonably assume, because of its age, that it might not be possible to get a direct like for like replacement. However, because the original design has never needed to be updated, an RPTS you buy today is completely interchangeable with one bought decades ago.
“We also meet many electricians and speciﬁers who still make the RPTS the ﬁrst choice for many applications including car park lighting, stairwell lighting, commercial heating systems and timed equipment control.”