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Nest thermostat shorts furnace

Community Member


I have nest thermostat which worked fine for a while until one day my furnace tripped. I called electricity provider in my area. After inspecting the furnace and wiring, he disconnected the blue wire which was connected to 'C' (Common) part in the thermostat. 

I was also told that I need to manually and regularly charge the thermostat, which is very painful.

In addition, the electrician told me that the furnace looks fine and the problem is likely in the thermostat. I am kind of lost how to debug the problem further.

Can I get some support?




C/common slot connection on nest is preferred so you have 24 volts all the time on R & C . You said Tripped you mean power outage or furnace malfunction? 

A fuse is tripping. 

If it’s a low voltage fuse then there’s some issue with the power side of the  thermostat wirings touching metal & trips low volt fuse. Might need to run new low voltage wires to make sure all are ok. Good luck.  

How to make sure thermostat is no causing tripping?

Hello everyone,

I wanted to ensure that everything was covered here.

Thanks for looking into this, HVAC.

@vikkastaneja, I appreciate you reaching out to us. In addition to what was mentioned above, the C wire may not be properly grounded. Are you getting any message codes or wiring reports on your Nest Thermostat? Please gather its power readings in the Technical Info settings.

I'll look forward to your response.


Hi vikkastaneja,


I don't want to be a nudge, but I'd like to check if you were able to get your thermostat working. Please let me know some details I need so we can move forward. Feel free to reach back if you still need help.