Overview
Shelly Z-Wave devices continuously monitor their internal temperature to protect the hardware from damage.
If the device detects that its internal temperature is above the safe operating limit, it will report an overheating event to the Z-Wave controller and indicate the condition using the status LED.
This article explains how to identify an overheating condition and what to check before contacting support.
How to Identify an Overheating Condition
An overheating device provides two indications:
- The device sends an Overheating Notification to the Z-Wave controller.
- The status LED starts blinking red using the following pattern:
LED indication:
- Red LED ON for 0.2 seconds
- Red LED OFF for 0.2 seconds
- LED OFF for 2 seconds
- The sequence repeats continuously
Pattern:
(0.2 s ON → 0.2 s OFF → 0.2 s ON → 0.2 s OFF → 2 s OFF)
Possible Causes
An overheating condition can be caused by one or more of the following:
- Connected load exceeds the device rating.
- Incorrect wiring.
- Poor ventilation around the device.
- Installation inside a very small or sealed electrical box.
- High ambient temperature.
- Continuous operation at high load.
Troubleshooting Steps
1. Check the Connected Load
Verify:
- What type of load is connected (LED lighting, incandescent lamp, motor, fan, heater, etc.).
- The total power of the connected load (W).
- The current drawn by the load (A), if available.
- The load is within the specifications of the device.
If the load exceeds the maximum supported rating, disconnect it immediately.
2. Check the Installation
Inspect the installation:
- Is the device installed inside a flush-mounted wall box?
- Is it installed inside a closed cabinet?
- Is there enough space around the device for heat dissipation?
- Is the device installed close to another heat source?
Poor ventilation may cause the internal temperature to increase.
3. Check the Wiring
Verify that:
- All wiring follows the wiring diagram.
- All terminals are tightened correctly.
- There are no loose connections.
- The neutral connection (if required) is connected correctly.
Loose connections can generate additional heat.
4. Check the Ambient Temperature
Measure or estimate the temperature around the installation.
If the surrounding environment is already very hot, the device may reach its thermal protection limit more quickly.
5. Observe When the Overheating Occurs
Check if the overheating happens:
- Immediately after powering the device.
- Only when the load is ON.
- After operating for several minutes.
- Only during specific times of the day.
This information helps identify whether the issue is related to the installation or the connected load.
Information to Collect Before Contacting Support
If the problem continues, collect the as many of the following information:
- Device model.
- Firmware version.
- Type of connected load.
- Total load power (W).
- Installation type (flush box, surface mounted, DIN rail, etc.).
- Photos of the installation.
- Photos of the wiring.
- Description of when the overheating occurs.
- Confirmation that the controller received an overheating notification.
Providing this information will help speed up the troubleshooting process.
Safety Notice
If the device repeatedly reports overheating:
- Disconnect the load if it is safe to do so.
- Do not continue operating the device until the cause has been identified.
- Verify that the connected load and installation comply with the device specifications.