The Legrand MicroRex BT timer is a compact, no‑nonsense 24‑hour analog time switch designed to give you reliable daily control over lighting, heating, ventilation, and other fixed loads. If you work with DIN rail panels, distribution boards, or small control enclosures, the Legrand MicroRex BT timer offers a simple way to automate schedules without the complexity of a PLC or the learning curve of a digital programmer.
In this guide, we’ll walk through what the Legrand MicroRex BT timer actually is, how it works, its technical specifications, how to mount and wire it, and where it makes the most sense to use it. Along the way, we’ll also compare it with alternative models in the MicroRex family so you can decide whether this particular Legrand MicroRex BT timer is the right fit for your application.
Legrand MicroRex BT Timer at a Glance
The Legrand MicroRex BT timer is an analog 24‑hour programmable time switch designed for DIN‑rail mounting in control panels and distribution boards. It provides a single output channel rated at up to 16 A, with a voltage rating of 250 V AC for resistive loads. In practical terms, that means the Legrand MicroRex BT timer can directly switch many lighting circuits, heaters, or small motors without needing an additional contactor—provided the load stays within its rated limits.
Physically, the unit is very compact. The Legrand MicroRex BT timer occupies just one standard 17.5 mm DIN module, so it fits neatly on a 35 mm DIN rail alongside breakers, contactors, and relays. On the front, you’ll find a clear hinged cover that protects the dial and segments, plus a 24‑hour clock face with numbered markings from 0 to 24. Around the dial are small captive segments that you push in or pull out to define when the timer should switch the output ON or OFF. This is the heart of how the Legrand MicroRex BT timer operates.
The device is powered by a synchronous motor clock that runs directly from a 230 V AC, 50 Hz supply. Because the Legrand MicroRex BT timer uses mains frequency for timekeeping, it does not require a separate quartz module or battery. That makes it both rugged and simple. At the same time, it means that if the supply fails, the time stops and the schedule will resume from the wrong time when power returns unless you manually reset the dial.
On the front face of the Legrand MicroRex BT timer you also have a three‑position manual override lever labeled I – Auto – O. This gives you immediate control without having to disturb the programmed segments. In the ON position, the output of the Legrand MicroRex BT timer stays energized permanently, regardless of the dial. In the OFF position, the output remains de‑energized. In Auto, the timer follows whatever 24‑hour schedule you programmed with the segments.
Inside the Legrand MicroRex BT Timer: Technical Specifications
To choose the Legrand MicroRex BT timer confidently, you need to understand its key specifications, ratings, and limits. These technical details determine which loads it can safely handle and in what environments it should be installed.
At its core, the Legrand MicroRex BT timer is supplied by 230 V AC, 50 Hz. The synchronous motor inside the Legrand MicroRex BT timer tracks the mains frequency, so one full rotation of the dial corresponds to 24 hours. You program the day by adjusting the small segments around the dial. Each segment represents a 15‑minute interval. The minimum ON time is therefore 15 minutes, and you can create multiple ON/OFF periods across the 24‑hour cycle by setting different segments on the Legrand MicroRex BT timer.
For the output, the Legrand MicroRex BT timer provides a single normally‑open contact rated at 16 A at 250 V AC for resistive loads (power factor cos φ = 1). In practice, that means the timer can handle many lighting circuits, resistive heaters, or small single‑phase motors directly. For larger or more inductive loads, you would typically use the Legrand MicroRex BT timer to drive a contactor coil instead of switching the load directly. This preserves the life of the contact inside the Legrand MicroRex BT timer and keeps the system within the product’s design envelope.
In terms of timekeeping accuracy, the Legrand MicroRex BT timer offers ±5 minutes per day under normal conditions. Because it relies on mains frequency, long‑term accuracy also depends on the stability of the grid. In many regions, frequency corrections over a 24‑hour period keep clocks close to real time, so the Legrand MicroRex BT timer is usually more than accurate enough for lighting, heating, and defrost applications.
Environmentally, the Legrand MicroRex BT timer is housed in an IP20 enclosure, which means it is intended for indoor use inside a protective panel or distribution board. The specified ambient operating temperature range is typically from about –10 °C up to around +55 °C, making the Legrand MicroRex BT timer suitable for most electrical rooms, technical spaces, and commercial interiors. Within that range, the mechanical dial and synchronous motor continue to operate reliably.
The unit conforms to important safety and control standards, such as EN 60730‑1 and EN 60730‑2‑7, which cover automatic electrical controls for household and similar use. It also meets relevant VDE 0631 parts, giving the Legrand MicroRex BT timer a solid compliance foundation. This helps designers and installers meet regulatory requirements when they specify the Legrand MicroRex BT timer in residential, commercial, and light‑industrial projects.
One important point is that the Legrand MicroRex BT timer does not include a power‑reserve battery. Legrand describes this as "without working reserve." If the supply voltage is lost, the clock stops, and when power returns you must reset the time on the Legrand MicroRex BT timer. The programmed ON/OFF pattern remains stored mechanically in the segments, but the actual time reference will be wrong until corrected.
How the Legrand MicroRex BT Timer Works in Real Installations
On paper, the Legrand MicroRex BT timer is a 24‑hour analog time switch with a 16 A output. In the field, however, what really matters is how it behaves in real installations. Because the Legrand MicroRex BT timer repeats the same cycle every 24 hours, it is ideal for daily routines that do not change often, such as turning lights on at night or starting a heater every morning.
Programming the Legrand MicroRex BT timer is deliberately simple. After powering the device, you rotate the dial clockwise until the current time aligns with the reference mark on the front. You then push in the segments for periods where you want the output ON, and leave them out where you want the output OFF. For example, if you want external lighting to run from 18:00 to 23:00, you push in all segments between those times on the Legrand MicroRex BT timer.
Once programmed, the Legrand MicroRex BT timer keeps rotating slowly, driven by its synchronous motor. Whenever the dial passes through a section with pushed‑in segments, the internal mechanism closes the contact and energizes your load. When the dial reaches an area with segments left out, the contact opens and the load switches off. This completely mechanical logic makes the Legrand MicroRex BT timer robust, easy to see, and easy to modify—no menus, no passwords, and no user manual required after a bit of practice.
The manual override lever adds an extra layer of practicality to the Legrand MicroRex BT timer. Imagine you have an exhaust fan controlled by the timer in Auto mode, but maintenance staff need the fan to run continuously for a few hours while cleaning. Instead of reprogramming the dial, you simply flip the Legrand MicroRex BT timer to the I (ON) position. When you’re done, you move it back to Auto and the schedule resumes. The OFF position can be just as useful when you want to temporarily disable a load without altering the programmed pattern.
In many control panels, several devices are stacked side‑by‑side, and space is at a premium. Because the Legrand MicroRex BT timer takes up only one module, it slots neatly between miniature circuit breakers, RCDs, or contactors. Its clear cover also makes it easy to see the timetable at a glance. This is especially important in multi‑tenant buildings, small commercial shops, and refrigeration panels where multiple timers might be present. The clear visual layout of the Legrand MicroRex BT timer reduces confusion and helps technicians understand which load is controlled by which time switch.
Another advantage of the Legrand MicroRex BT timer is that it is easy to explain to non‑technical users. Building managers, store owners, or maintenance staff can typically be shown in just a few minutes how to adjust the segments. That means they can make simple changes themselves—like extending lighting hours for a special event—without calling an electrician every time. When you design systems with the Legrand MicroRex BT timer, you gain both technical reliability and user‑friendly operation.
Mounting and Wiring the Legrand MicroRex BT Timer Safely
Before installing the Legrand MicroRex BT timer, always isolate the supply and follow local electrical regulations. The device is intended for fixed installation on a 35 mm DIN rail, usually inside a distribution board or control panel. Because the Legrand MicroRex BT timer has an IP20 rating, it must be mounted in an enclosure where users cannot directly touch live parts.
Mechanically, mounting the Legrand MicroRex BT timer is straightforward. You hook the top of the housing onto the DIN rail and then press the bottom until the spring clip snaps into place. This is similar to mounting a miniature circuit breaker. Once secured, the Legrand MicroRex BT timer sits flush with other modular devices. If you ever need to remove it, you pull down the release tab (if provided) or lever the clip and tilt the unit off the rail.
On the underside of the Legrand MicroRex BT timer, you will find screw terminals clearly marked for the mains supply and load connection. Typically, one pair is labeled L and N for the 230 V supply that powers the clock. Another pair of terminals forms the output contact: a common terminal (often marked with a symbol or number) and a normally open terminal. You connect the line conductor that feeds your load through this output of the Legrand MicroRex BT timer, while the neutral usually goes directly to the load, as per the wiring diagram.
When sizing conductors for the Legrand MicroRex BT timer, choose wires that match the current rating and follow the panel’s design rules. Because the timer is rated for 16 A, many installers use 1.5 mm² or 2.5 mm² copper conductors for typical lighting or heating loads, depending on local standards. Tighten all screw terminals to the manufacturer’s recommended torque so that the Legrand MicroRex BT timer maintains reliable connections and avoids hotspots.
After wiring, check the front of the Legrand MicroRex BT timer. Set the manual lever to OFF, energize the panel, and verify that the timer receives its 230 V supply. Then set the current time on the dial and move the lever to Auto. You can test the switching by rotating the dial manually past a programmed segment; the output should click and the connected load should respond. This commissioning step ensures that the Legrand MicroRex BT timer is wired correctly and that both the clock and contact are functioning.
Because there is no internal power reserve, you may also want to label the panel indicating that the Legrand MicroRex BT timer loses time after a power failure. This small note can save troubleshooting later. In some panels, designers combine the Legrand MicroRex BT timer with a digital timer that has battery backup for more critical loads, while using the analog timer for non‑critical or easy‑to‑reset circuits.
Legrand MicroRex BT Timer vs Alternative Models
Within the Legrand family, the Legrand MicroRex BT timer is one member of a broader range of daily and weekly time switches. Understanding these alternatives helps you choose the model that balances simplicity, flexibility, and resilience for your project.
One close relative of the Legrand MicroRex BT timer is the MicroRex QT11. Electrically, the QT11 has very similar ratings: a 230 V AC supply, a 16 A output contact, and 24‑hour programming. However, the QT11 version adds a quartz‑controlled clock and a working reserve, often around 100 hours. That means, unlike the analog Legrand MicroRex BT timer, the QT11 can keep time even during power interruptions, thanks to its internal backup. If your installation suffers frequent outages, the QT11 or similar models might be worth the extra cost.
Legrand also offers alternative dial layouts, such as the T31 or QT31 timers. These are generally wider, three‑module devices with horizontal dials and longer minimum switching steps—typically 30‑minute intervals instead of the 15‑minute granularity of the Legrand MicroRex BT timer. For applications where you don’t need fine time resolution, and where extra panel space is available, these models provide a more spacious dial that some technicians find easier to read.
For weekly scheduling, Legrand provides QW11 and QW31 models. Instead of repeating the same pattern every 24 hours, these timers allow different settings for each day of the week. If your system needs weekday/weekend differentiation, weekly timers may be more appropriate than the daily Legrand MicroRex BT timer. However, for many straightforward everyday routines—like shop signs, corridor lighting, or daily defrost—the simplicity of a 24‑hour repeat is actually an advantage.
In the digital realm, Legrand’s MicroRex D21 Plus and D22 Plus bring LCD displays, push‑button menus, and multiple programmable events. These digital timers often support advanced features like holiday programs, random switching, or astro functions in some ranges. Compared to the analog Legrand MicroRex BT timer, digital models require more setup time and familiarity with menus, but they offer much greater flexibility for complex schedules.
Ultimately, the decision often comes down to what the end user needs. Many installers choose the Legrand MicroRex BT timer precisely because it is easy for non‑technical staff to see and adjust. Others prefer digital models when the system calls for many different on/off events, multiple channels, or a weekly calendar. In mixed panels, it is common to see the Legrand MicroRex BT timer handling simple tasks while digital timers tackle more sophisticated control logic.
Applications: Where the Legrand MicroRex BT Timer Really Shines
The Legrand MicroRex BT timer is best suited to applications where you have a simple, repetitive daily schedule. Its 15‑minute resolution makes it a natural choice for lighting, heating, and defrost control, where small shifts in timing are useful but second‑level or minute‑by‑minute programming is unnecessary.
One of the most common uses of the Legrand MicroRex BT timer is lighting control. For example, you might use the timer to switch on exterior building lights at dusk and turn them off later in the evening. Even though the Legrand MicroRex BT timer does not automatically track sunrise and sunset, it still offers significant energy savings by preventing lights from running all night. Building managers can adjust the segments seasonally to match changing daylight.
Another strong application for the Legrand MicroRex BT timer is small heating systems, such as panel heaters in offices, waiting rooms, or entrance lobbies. Instead of leaving heaters on all day, you can program them to run only during occupancy periods. The 16 A contact of the Legrand MicroRex BT timer can directly switch many single‑phase heaters, or you can drive a separate contactor for larger systems. Either way, you gain predictable comfort and lower energy consumption.
In refrigeration and cold‑room installations, the Legrand MicroRex BT timer often controls defrost heaters or fans. The 15‑minute minimum step is ideal for typical defrost cycles, which need fixed periods of heat to clear ice buildup. Because the schedule repeats every 24 hours, technicians can set one or more defrost events each day with the Legrand MicroRex BT timer, ensuring consistent temperature control and equipment reliability.
Ventilation is another common scenario. Exhaust fans in restrooms, changing rooms, or small workshops do not always need to run continuously. With a Legrand MicroRex BT timer, you can schedule fans to run during peak usage hours while keeping noise and energy use down during quiet times. The intuitive dial makes it easy for facility staff to modify ventilation schedules even if they are not familiar with advanced automation systems.
The Legrand MicroRex BT timer also appears in small water‑pumping or irrigation setups, especially in commercial or light‑industrial environments. For instance, you could program a pump to run for specific periods each day, such as early morning and late afternoon. While more complex agricultural systems might call for advanced controllers, many simple pump applications work perfectly with a reliable daily time switch like the Legrand MicroRex BT timer.
Beyond these examples, any repetitive daily process that doesn’t require high‑precision timing or a weekly calendar is a potential candidate. The Legrand MicroRex BT timer offers enough granularity for many tasks while staying easy to understand, which is a major advantage when installations will be serviced by general maintenance staff instead of automation specialists.
Choosing the Right Timer: Is the Legrand MicroRex BT Timer Right for You?
With so many timing devices on the market, it’s worth stepping back and considering when the Legrand MicroRex BT timer is the most appropriate choice. Start by looking at your load. If your load is 230 V AC and draws 16 A or less (resistive), you can often switch it directly with the Legrand MicroRex BT timer. If the load is larger, inductive, or three‑phase, then the timer will usually act as a control device for a contactor instead. In either case, the Legrand MicroRex BT timer can still form the heart of a reliable, daily control scheme.
Next, consider your schedule complexity. If you just need one or a handful of fixed on/off periods that repeat every day, the analog Legrand MicroRex BT timer is an excellent fit. You simply adjust the segments and go. If you need a different schedule on weekends, holiday exceptions, or many switching events spread across the week, you may be better off with a weekly or digital timer instead of the daily Legrand MicroRex BT timer.
A third factor is who will interact with the device. In many buildings, the people responsible for adjusting timer settings are not engineers—they’re caretakers, store owners, or office managers. The Legrand MicroRex BT timer shines in these environments because the dial visually shows exactly when the output will be ON and OFF. Once you explain that pushed‑in segments mean ON periods, most users can manage minor changes on their own. Digital timers, by contrast, sometimes intimidate non‑technical staff who fear mis‑programming the device.
You should also think about power reliability. Because the Legrand MicroRex BT timer has no working reserve, it will lose time during long outages. In areas with frequent blackouts, it may require occasional manual correction. If that is a concern, you might pair the Legrand MicroRex BT timer with a model that includes a battery reserve or use it only on circuits where a few hours of timing error after an outage is acceptable.
Finally, consider panel space and aesthetics. The slim 1‑module form factor of the Legrand MicroRex BT timer makes it attractive for compact panels, refurbishments, and applications where you are retrofitting automation into an existing board. Its neutral, professional design blends well with typical DIN‑rail components, and the transparent cover protects the dial while keeping the schedule visible. For many installers, these small details make a big difference when presenting a clean, organized panel to the client.
If, after reviewing these points, you find that you need simple, daily, robust time control with minimal user training, the Legrand MicroRex BT timer is likely a very strong candidate.
Related Product Collections for Legrand MicroRex BT Timer Installations
If you’re planning to use the Legrand MicroRex BT timer in a panel or project, these related product collections can help you complete the rest of your build with compatible components and accessories:
- Legrand – Electrical Components & Accessories ➜ A brand‑focused collection featuring Legrand terminal blocks, distribution accessories, enclosures, and other modular devices that pair naturally with the Legrand MicroRex BT timer in professional control panels.
- Omron – Timers, Relays & Automation Products ➜ A broad range of Omron automation hardware, including analog and digital timers, relays, and control components that complement or provide alternatives to the Legrand MicroRex BT timer in more complex control schemes.
- Contactor & Overload – Motor Control & Protection ➜ A dedicated collection for contactors and overload relays, ideal when you use the Legrand MicroRex BT timer as a control signal to switch larger or more inductive loads safely and efficiently.
Conclusion: Getting the Most from Your Legrand MicroRex BT Timer
The Legrand MicroRex BT timer brings together simplicity, robustness, and everyday practicality in a compact DIN‑rail package. With its 24‑hour analog dial, 15‑minute switching steps, and 16 A output contact, it offers more than enough capability for many lighting, heating, ventilation, and defrost applications. At the same time, the mechanical dial and ON–AUTO–OFF lever make the Legrand MicroRex BT timer easy for both technicians and non‑technical users to understand at a glance.
By understanding the specifications, wiring, operating environment, and alternatives, you can confidently decide where the Legrand MicroRex BT timer fits into your overall control strategy. Whether you are building a new panel or upgrading an existing board, this time switch can help you deliver predictable schedules, improved comfort, and better energy management with minimal complexity.
If you are considering the Legrand MicroRex BT timer for your next project, take a moment to review the full product details, wiring diagrams, and related accessories on the product page. Exploring that information will help you match the Legrand MicroRex BT timer to the right loads and applications, so your installation stays safe, efficient, and easy to maintain over the long term.