By Frédéric Reisz
UTC Compiègne Engineer • CEO Electrical Expert for 20 years
What is a modular timer?
It is a control device that opens or closes an electrical circuit according to a defined time range.
- Breaking capacity: Most standard models support up to 3600W (16A at 230V).
- Use: Ideal to avoid unnecessary consumption during peak hours or at night.
Always switch off the main circuit breaker before any intervention. Check for absence of voltage with a VAT (Voltage Absence Tester). If in doubt, call a qualified electrician.
Installation guide in 3 steps
Step 1: Installation and power supply on the DIN rail
The timer is installed on the metal rail of your electrical panel, generally after a 2A protection circuit breaker.
- Mounting: Clip the timer and the 2A circuit breaker onto the rail.
- Power supply connection: Connect the Phase (red) and Neutral (blue) from the main distribution block to the upstream side of the 2A circuit breaker. Connect the output of the 2A circuit breaker to the power supply terminals of the timer (generally marked L and N).
- Wire section: Use 1.5 mm² wire.
Step 2: Wiring the control circuit
This is where you connect the device you want to control.
- Wire identification: Your device has a Phase (red/black), a Neutral (blue) and an Earth (green/yellow).
- The dry contact principle: The timer acts like a switch. You must route the device’s phase wire through the timer.
- Connection:
1. The Neutral and Earth of the device remain directly connected to its original protection circuit breaker.
2. Disconnect the Phase of the device from its circuit breaker and connect it to the output terminal of the timer contact.
3. Add a jumper wire between the output of the timer contact and the phase terminal of the device circuit breaker.
- Wire section: Respect the original circuit section (e.g.: 2.5 mm² for a water heater) and check that the timer has a breaking capacity higher than the device to be controlled.
Step 3: Configuration and programming
Once the power is restored, proceed with configuration according to your needs:
| Timer type | Recommended use | Advantage |
|---|---|---|
| Daily | Water heater, heating | Simple daily repetition |
| Weekly | Offices, shops | Different management for weekends/weekdays |
| Astronomical | Outdoor lighting | Adapts to sunrise and sunset times |
The modern extra: Recent models offer programming via Smartphone (NFC, Bluetooth or Wi-Fi), making the interface much more intuitive than old mechanical pins.
Frequently Asked Questions (FAQ)
Why install a modular timer in your electrical panel?
The modular timer is an automatic time switch. Its main role is to save energy by controlling your devices (water heater, pool pump, outdoor lighting) only during the desired time slots (off-peak hours for example). It generally supports a power up to 1800W (8A).
Which circuit breaker should be used to protect an electrical timer?
For a compliant installation, the timer power supply must be protected by a 2A circuit breaker. The connection is made with 1.5 mm² wire. Note that the controlled device keeps its own protection circuit breaker (often 10A or 16A).
What is a "dry contact" on a modular timer?
The dry contact works like a simple switch: it only cuts the Phase wire of your equipment. The Neutral and Earth remain directly connected to the terminal block. For a water heater, it is mandatory to use a wire section identical to the original circuit, generally 2.5 mm².
What is the difference between a daily and an astronomical timer?
The daily timer repeats the same program every day. The astronomical timer is smarter: it calculates sunrise and sunset times according to your geographical location, which is ideal for outdoor lighting. Today, these models are easily set via Smartphone (NFC or Bluetooth).
Can you install a timer without cutting the power?
No. Safety is absolute: you must switch off the main circuit breaker and check for absence of voltage with a VAT. If you have no experience in electricity, the expertise of a professional is strongly recommended to modify your electrical panel.
Can you connect a 3000W water heater to a 16A timer?
Although the timer can technically support the load, it is strongly recommended to use the timer to control the coil of a contactor. This protects the timer contacts against premature wear due to high power.
Can you connect a device over 4000W or more to a timer?
Indirectly, yes. Simply install a power contactor with a rating suitable for the device. The contactor will cut the phase (single-phase device) or the phases (three-phase device) of the device at the desired times. The timer contact will be connected to the control input of the contactor to indicate switching on and off times.
