Two Doorbell Wiring with Tri-volt Transformer
Get a plain-language answer to two doorbell wiring with tri-volt transformer, with setup notes, compatibility details, and links to related help and.
Updated: July 27, 2026Original publish date: August 7, 2025
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Short answer: This page explains two doorbell wiring with tri-volt transformer in practical terms, with links to the products, setup guides, and troubleshooting steps that usually matter next.
Using 16V Output @ 10VA for Two Doorbells
Step-by-Step Wiring Instructions
⚠️ Safety First: Turn off power at the circuit breaker before beginning any electrical work!
- Install the Transformer:
- Connect 120V household power to primary side (hot, neutral, ground)
- Locate the 16V output terminals on the secondary side
- Run Power Wires (Parallel Connection):
- From the 16V terminal, run a red wire to a junction point
- Split from junction to both doorbells’ TRANS terminals
- From the COM terminal, run a black wire to a junction point
- Split from junction to both doorbells’ COM terminals
- Connect Push Button 1 (Front Door):
- Run wire from Doorbell 1’s FRONT terminal to Button 1
- Run wire from Button 1 back to Doorbell 1’s TRANS terminal
- Connect Push Button 2 (Back Door):
- Run wire from Doorbell 2’s FRONT terminal to Button 2
- Run wire from Button 2 back to Doorbell 2’s TRANS terminal
- Test the System:
- Turn power back on at circuit breaker
- Press each button – each should ring its respective doorbell
💡 Pro Tips:
- Use 18-20 AWG bell wire for all low-voltage connections
- Label wires at both ends for future maintenance
- Two typical doorbells (5VA each) = 10VA total, which is perfect for the 16V 10VA tap
- Wire nuts or terminal blocks work well for creating junction points
How It Works
When a button is pressed, it completes the circuit:
- Power flows from transformer 16V terminal → doorbell TRANS terminal
- Through the doorbell → out the FRONT terminal
- Through the pressed button
- Back to the doorbell TRANS terminal → to transformer COM
- This completed circuit activates the chime
Important: Each doorbell operates independently. Pressing one button only rings its connected doorbell, not both.
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