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Two Doorbell Wiring with Tri-volt Transformer

Table of Contents

Using 16V Output @ 10VA for Two Doorbells

TRI-VOLT TRANSFORMER 120V INPUT 8V 10VA 16V 10VA 24V 20VA LOAD 16V COM 16V 10VA (Selected Output) DOORBELL 1 FRONT DOOR (16V Chime) TRANS COM FRONT DOORBELL 2 BACK DOOR (16V Chime) TRANS COM FRONT BUTTON 1 FRONT BUTTON 2 BACK Junction Box (Wire Nuts/Terminals) 16V Power Common Current Flow
Wire Color Legend Red Wire 16V Power from transformer Black Wire Common/Neutral (COM) Yellow Wire Doorbell FRONT to push button Red (Dashed) Button return to TRANS terminal i Use 18-20 AWG bell wire for all connections. Keep low-voltage wiring separated from 120V wiring. Wire nuts or terminal blocks work well for creating junction points in parallel wiring.

Step-by-Step Wiring Instructions

⚠️ Safety First: Turn off power at the circuit breaker before beginning any electrical work!

  1. Install the Transformer:
    • Connect 120V household power to primary side (hot, neutral, ground)
    • Locate the 16V output terminals on the secondary side
  2. 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
  3. 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
  4. 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
  5. 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:

  1. Power flows from transformer 16V terminal → doorbell TRANS terminal
  2. Through the doorbell → out the FRONT terminal
  3. Through the pressed button
  4. Back to the doorbell TRANS terminal → to transformer COM
  5. This completed circuit activates the chime

Important: Each doorbell operates independently. Pressing one button only rings its connected doorbell, not both.