APNT-158 - Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using Fibaro Dimmer 2

IMPORTANT - Read this first!

Note: To simplify these diagrams, we have not shown the earth cables - but all circuits MUST have the earth cable correctly installed.

We've shown wires in red to indicate that they are new wires, but it doesn't really matter what colour you use.

To protect the module a suitable rated overcurrent protection fuse must be installed on the Live input.

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One of the things that confuses people the most is installing home automation into an existing 3-Way lighting system, especially when it uses Intermediate Switches. This application note looks at how a Fibaro Dimmer 2 module can be installed to control a 3-Way lighting system with an Intermediate Switch and Neutral available.

Firstly, what do we mean by 3-Way lighting?

This simply refers to a lighting system where one light is controlled by three light switches. Examples of this are where a room has three entrances (each needs a light switch) or for a hall light that can be controlled from 3 different switches.

This wiring is based on a UK style 3-wire lighting system with neutral wire at the switch. More information about 3-wire lighting systems is available in APNT-23: Understanding 2-wire and 3-wire Lighting Systems.

For information on how to physically install a Z-Wave module take a look at our guide here.

To know more about how Z-Wave modules work with different switch types make sure to read our guide here.

 

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral)

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) Figure 1: Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral)

This system uses two 2-way switches (as you find in a 2-way circuit), but it also includes an Intermediate Switch that is in the "middle" of the circuit. All switches are toggle type and each can control the light On/Off.

2-Core cables (brown and blue) carries Live and Neutral to the wall switch and Switched Live and Neutral up to the light fitting. An extra 2-Core cable (brown and grey) connects the three wall switches together with a single wire connecting the two Toggle Switches, enabling each of them to independently turn the light On or Off.

This type of lighting system uses "Toggle" (latching) switches. These latch in position - for instance when you press the switch to On, the switch physically stays in the On position. These are the standard light switches you'll find already fitted in your home.

The module can also be used with a variety of "Momentary" switch types and configurations. Momentary switches, also known as Retractive or Bell-Push, only remain in the On state while you press them, they return to the Off state when the button is released.

This doesn't mean that you have to keep holding the button to keep the light on. The module's internal controls automatically keep the light on when the button is released.

More information about how the Fibaro Dimmer 2 works with different switch types is available here.

We can install the module into this 3-Way circuit in various different ways shown below. We've separated out the diagrams based on whether you need to install the module at Switch A or Switch C position.

Fibaro Dimmer 2 Connections

The Fibaro Dimmer 2 has six terminals to connect it to the electrical wiring:

Fibaro Dimmer2 Connections

 

  • L – Live
  • S2 – connection to Switch 2
  • S1 – connection to Switch 1
  • Sx – switch common
  • N – Neutral (this is connected to Sx in 2-wire installations)
  • ~ (Output) – connected to light or load

Fibaro Dimmer 2 Parameter Setting:

The following parameters may need to be set:

  • 20 - 0 - enables the module to work with momentary switch (default)
  • 20 - 1 - enables the module to work with a toggle switch
  • 20 - 2 - enables the module to work with a 3-position momentary switch
  • 26 - 1 - enables the modules' S2 switch to also control the load (default 0)

Installation at Switch A position

You will install the Fibaro Dimmer 2 module at the Switch A position where it has access to both Permanent Live and Switched Live (load).

 

Toggle Switches

To retain your existing standard Toggle switches, we can simple install the Fibaro Dimmer 2 module as shown in Figure 2.

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Toggle switches (Switch A) Figure 2: Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Toggle switches (Switch A).

In this case we keep the standard Toggle switches connecting "L1" to the module's S1 input and "L2" connected to the module's Sx output. Live and Neutral is wired to L and N terminals and Switched Live (Load) to the module's Output.

This gives simple On / Off control of the light from the switches but you will still be able to control the dimming level over Z-Wave if required.

 

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

  • 20 - 1 - enables the dimmer to work with a toggle switch (default is 0 for a momentary switch)
  • 26 - 0 - keep as default

 

Momentary Switches

For full On / Off and dimming control we can replace the Toggle wall switches with similar styled Momentary switches.

 

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch A)Figure 3: Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch A).

Replace the existing Toggle and Intermediate switches with Momentary switches, connecting "L1" to the module's S1 input and "COM" connected to the module's Sx output. Live and Neutral is wired to L and N terminals and Switched Live (Load) to the module's Output.

Any unused wires from the original wirings should be safely terminated.

 

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

  • 20 - 0 - keep as default to work with a momentary switch
  • 26 - 0 - keep as default

 

3-Way with Z-Wave Wall Switch

Sometimes you may require a 2-Way or multi-way lighting circuit where physical wiring doesn't already exist, or perhaps you need to re-purpose the existing wiring for something else.

Z-Wave makes this possible using something known as "Associations" - where one Z-Wave device can control another Z-Wave device directly without inter-connecting wiring. More information on Associations can be seen in our guides here and here.

Using Z-Wave Switches in a Alternate 2-Way Lighting Circuit (with Neutral) with Fibaro Dimmer 2 (Switch A)Figure 4: Using Z-Wave Switches in a Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 (Switch A).

To create this circuit you simply install the module to suit either Toggle or Momentary switches and safely terminate the cables as required. A battery powered Z-Wave Wall Controller can then be Associated to the module.

Any unused wires from the original 2-core between the two switches should be safely terminated. Don't forget to configure the module for Toggle or Momentary switches!

Installation at Switch C position

In some circumstances it may not be possible to install the Fibaro Dimmer 2 module at the Switch A position - perhaps there's not enough room physically to install it there, or perhaps that position is out of range of the Z-Wave netwok. In this case sometimes it's possible to install at the Switch C position but there are a number of caveats because in this position it won't have access to Live or Switched Live wires.

 

Toggle Switches - add additional 3-core cable between switches

 

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch C)Figure 5: Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Toggle switches (Switch C).

Connect Switch  "L1" to the module's S1 input and "L2" to the module's Sx output. An additional 3-Core cable is added to take Live, Neutral and Switched Live from Switch A position to the module at Switch C.

 

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

  • 20 - 1 - enables the module to work with a toggle switch (default is 0 for a momentary switch)
  • 26 - 0 - keep as default

 

Momentary Switches - add additional 2-core cable between switches

For full On / Off and dimming control we can replace the Toggle wall switches with similar styled Momentary switches.

 

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch C)Figure 6: Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch C).

Replace the existing Toggle switches with Momentary switches, connecting "L1" to the module's S1 input with "COM" connected to the module's Sx output. The original "COM" wire is used to take Live to Switch C position and an additional 2-core cable is added to take Neutral and Switched Live to Switch C position.

 

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

  • 20 - 0 - keep as default to work with a momentary switch
  • 26 - 0 - keep as default

 

Toggle Switches - re-wire Neutral, Live and Switched Live to Switch C

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch C)Figure 7: Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Toggle switches (Switch C).

Connect Switch “L1” to the module's S1 and "L2" to the module's Sx output. Live, Neutral and Switched Live are re-wired to Switch C position.

This gives simple On / Off control of the light from the switches but you will still be able to control the dimming level over Z-Wave if required.

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

  • 20 - 1 - enables the module to work with a toggle switch (default is 0 for a momentary switch)
  • 26 - 0 - keep as default

 

Momentary Switches - re-wire Neutral and Switched Live to Switch C

Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch C)Figure 8: Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 with Momentary switches (Switch C).

Simillar to the above scenario but this time replace the existing Toggle switches with Momentary switches, connecting "L1" to the module's S1 input with "COM" connected to the module's Sx output. The original "COM" wire is used to take Live to Switch C position, Neutral and Switched Live is re-wired to Switch C position.

 

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

  • 20 - 0 - keep as default to work with a momentary switch
  • 26 - 0 - keep as default

 

3-Way with Z-Wave Wall Switch

Using Z-Wave Switches in a Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 (Switch C)Figure 9: Using Z-Wave Switches in a Standard 3-Way Lighting Circuit with Intermediate Switch (with Neutral) using the Fibaro Dimmer 2 (Switch C).

Here we replace Switch A and Switch B with a Z-Wave Wall Switch and install the Dimmer 2 at Switch C position. Connect Switch C “L1” to the module's S1 input with "COM" connected to the module's Sx output. We use the original "L1" wire to bring over Live from the first switch position, orignal "L2" wire to bring over Neutral and the original “COM” wire to take Switched Live back to Switch A position.

A battery powered Z-Wave Wall Controller can then be Associated to the module. More information on Associations can be seen in our guides here and here.

 

Install at Switch C and use S2 from Dimmer 2 at Switch A and Switch B

Install at Switch C and use S2 from Dimmer 2 at Switch AFigure 10: Install at Switch C and use S2 from Dimmer 2 at Switch A and Switch B.

Here we connect Switch A “L1” to Module A S2 input, Switch B “L1” to Module B S2 input. Connect Switch C “L1” to the Module C S1 input with "COM" connected to the Module C Sx output. We use the original "L1" wire to bring over Live from the first switch position, "L2" to bring over Neutral and the original “COM” wire to take Switched Live back to Switch A position.

More information on how to use a Secondary Switch with a Fibaro Dimmer 2 module can be found here.

Note: power to module at Switch A not shown as this would typically be taken care of for switching the other gang in a 2-gang switch.