Transformer Upgrade & Chime Wiring Confusion

[SteveJake]

EDITED to correct existing wiring information.

Hello! I just moved into a new (to me) house that was built in the late 80's. It has a front and rear doorbell, and the ancient transformer is only 12v so I need to upgrade it to 24v to run Google Nest doorbells (both front and rear).

Issue #1 - I finally found the transformer in the crawl space and it's not easy to get to but workable. May need to move it away from some other equipment for better accessibility but that's another matter.

I'm assuming that I just transfer the wiring the way it is currently configured to the new 24v transformer. There are four wires connected to it. This is my amateur analysis of what I'm seeing.

• White lead from the front button and chime front are twisted together

• White lead from the back button and chime back are twisted together

• Red lead from front and back chime wires are connected to one transformer contact

• Red lead from front and back buttons are connected the other transformer contact

If I just switch out the transformer, connecting everything exactly the same way to the new one, will both my camera doorbells work? 

Google's wiring diagram is a bit confusing, since I have four wires and this shows two, plus a single red going from the transformer to the chime TRANS connector....  

Based on this, I created a schematic drawing of what appears to be going on with this wiring. I'm not an electrician, obviously, so please forgive my amateur attempt.

 

Issue #2 - I want to be able to use the chime, but the wiring here seems strange as well. I hope I've captured the wiring correctly in my drawing above. Here's a pic of the chime wiring:

Disclosure: I haven't yet bought the doorbells, I'm just evaluating and planning first so I can hopefully be ready to get it all working on the first attempt. 

Any assistance will be greatly appreciated! Hopefully I've stated everything clearly enough... crossing fingers. I'm normally pretty good with electrical wiring challenges but this is completely new territory to me.

[Lance_L · Accepted solution]

Hello SteveJake,

Thanks for reaching out to the Community. I’ll be happy to help you with your questions.

Aside from the second red wire going from the TRANS terminal from the chime to the transformer, the top and bottom wiring diagrams are almost identical (if we disregard the chime connectors). The two red wires from the TRANS terminal of the chime to the transformer are basically doing the same job: connecting one terminal to another.

Once you replace the existing doorbell buttons with the Nest Doorbell (wired, 2nd gen), just connect the new doorbells to the existing chime wires, then connect the chime connectors as shown in the top wiring diagram.

If you still need assistance, you may contact a Nest Pro to help you install the device. In the US, you can contact our installation partner, OnTech, to help you set up the Nest doorbell. For all other countries, you can book an appointment with a Nest Pro. You can check out this handy guide for information on Google Nest professional installation services.

Reach out if you have any questions.

Best,

Lance

[SteveJake]

Hi Lance, thank you so much for your response. The more I studied it, the more I realized what you're saying—that the only difference is the extra TRANS wire. Essentially, the second wire just sort of beefs it up, however unnecessary it may be. Seems like I'm good to go here! 

[Jenelyn_O]

Hi there,

We're glad to hear that everything seems good here. Please feel free to let us know if you have any questions or concerns by creating a new thread, as we'll be willing to assist you. 

I appreciate your help, Lance.

Cheers,

Jenelyn