How Do I Install the Fibaro Dimmer 2 Bypass?
- Connected to 5GHz WiFi instead of required 2.4GHz network
- Light not properly reset before pairing attempt
- Weak WiFi signal at the light location
Problem Description
You need to install the Fibaro Dimmer 2 bypass module for LED bulbs. The bypass is needed when dimming LED bulbs below 50W total load — without it, LEDs may flicker, buzz, or not turn off completely. The bypass is a small module that wires in parallel with the light fixture inside the ceiling box. This guide covers why you need it and how to wire it.
Symptoms
- Light shows as offline in the app
- Light does not respond to on/off commands
- Colors appear incorrect or washed out
- Brightness controls not working
- Light flickers or turns off unexpectedly
- Voice commands through Alexa or Google fail
- Scheduled automations do not trigger
Recognize these? Here's what usually causes it.
Common Causes
- Connected to 5GHz WiFi instead of required 2.4GHz network
- Light not properly reset before pairing attempt
- Weak WiFi signal at the light location
- Hub or bridge disconnected from router
- App needs updating to latest version
- Light firmware is outdated
- Too many devices on the same network causing congestion
Most fixes happen in the first 3 steps.
Do not attempt to open or modify the light hardware. Smart lights contain electronic components that can be damaged by moisture or physical tampering. Always power off at the wall switch before removing or repositioning a smart light.
Tools & Requirements
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Step-by-Step Solution
Understand why the Fibaro Dimmer 2 needs a bypass
The Fibaro Dimmer 2 is a Z-Wave micro module that installs behind your wall switch. It draws power through the light circuit. With LED bulbs that draw very little power (under 50W total), the Dimmer 2 cannot draw enough idle current to operate its radio and processor. This causes flickering, the LEDs glowing faintly when off, or the module losing Z-Wave communication. The Fibaro Bypass (FGB-002) solves this by providing a minimum load path.
Install the bypass at the light fixture, not the switch
The Fibaro Bypass connects across the load — at the light fixture, in parallel with the bulbs. Turn off the breaker. At the fixture junction box, connect one bypass wire to the live (switched) wire and the other to the neutral wire. The bypass goes in parallel with your LED bulbs. Do not install it at the switch box — it must be at the fixture end of the circuit to work correctly.
Verify the bypass resolved the issue
Turn the breaker back on. The LED bulbs should now turn fully off without any ghost glow. Dim the lights down — flickering at low levels should be eliminated or significantly reduced. Test the Z-Wave connection by controlling the Dimmer 2 from your hub. If the module was previously dropping off the network, it should now maintain a stable connection because it has enough idle current.
Fix if the bypass does not help
If ghost glow or flickering persists after installing the bypass, the issue may be the LED bulbs themselves rather than the Dimmer 2. Test with a different LED brand — some LEDs have poor internal capacitor designs that cause glow regardless of bypass. Philips and Osram dimmable LEDs have the best compatibility with the Fibaro Dimmer 2. Also check that the bypass wires are making solid contact — a loose connection makes the bypass ineffective.
Configure the Dimmer 2 parameters for LED mode
In your Z-Wave hub, access the Fibaro Dimmer 2 configuration parameters. Set Parameter 1 (minimum brightness) to 5-15% to avoid the range where LEDs flicker. Set Parameter 2 (maximum brightness) to 95-99% to prevent LED driver stress. Set Parameter 30 to value 2 for trailing-edge dimming mode, which is the correct mode for LED bulbs. Leading-edge mode (value 1) works for incandescent but causes LED problems.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If flickering only happens on dimming, the issue is almost always the dimmer's minimum-load setting, not the bulb — it's drawing less current than the dimmer expects.
Group your smart lights by room in the app and assign clear names like Kitchen Ceiling and Bedroom Lamp. This makes voice commands more reliable and lets you create scenes that control multiple lights at once with a single command.
This issue almost always looks more complex than it is — the majority of cases trace back to a single setting, a stale credential, or a default that shipped wrong.
- Connected to 5GHz WiFi instead of required 2.4GHz network
- Light not properly reset before pairing attempt
- Weak WiFi signal at the light location
- Hub or bridge disconnected from router
- App needs updating to latest version
Before you go — try one of these (they fix most cases).
Official Manufacturer Manual
Fibaro provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your Fibaro Dimmer 2.
Source: manuals.fibaro.com
Need More Help? Fibaro Support
Note: The contact information below connects you directly to Fibaro's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.
