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Maximum relay coil resistance

Community Member

Hi, the Nest Thermostat detects if a (Y,W) wire is connected to the thermostat by measuring the resistance.  It expects a standard relay coil with a typical resistance of 300 Ohm. I am planning to replace the relay with a relay that has 3390 Ohm and I am concerned that the thermostat will refuse to operate such a relay. In the past, I've seen a specification for the maximum resistance (so, I know it is available) but I cannot find it anymore. Does anyone have that number?

Without actually buying the relay and see if it works, I have no way of verifying. I could go on and on about why I want to use such a relay but, I am sure I would cause you to fall asleep...

I could run a resistor in parallel but that's a bit ugly.



Community Specialist
Community Specialist

Hello paulnederland,


Interesting! Thanks for reaching out to the Google Nest Community. I'd love to help.

Connecting it to 24 Volts and measuring the current is probably the best way. Be sure to determine if it is meant to be powered by DC or AC before you connect it. Also, I found an article about the Nest Thermostat's technical specifications which might help.


Feel free to let us know if you have more questions.




Community Specialist
Community Specialist

Hi everyone,


@paulnederland I'm dropping by to ensure that everything is covered here. Were you able to read and check what Mark shared above? In case you have an update, you know where to find us.


I appreciate the help, Mark.



Community Specialist
Community Specialist

Hi paulnederland,


I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.