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: September 15, 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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Which doorbell button do I need for a duplex?A duplex with one shared front door needs one button per unit on a single plate, so each visitor can ring the right household. Pick the Lee BC203 if the chimes are electronic or.Is there a doorbell button for three apartments?Yes. The Lee BC208 three-family station puts three unlighted buttons and three name plate pockets on one plate about 7 inches tall, in polished brass or polished chrome. Each.Can one transformer run two doorbell chimes in a two-family house?Yes, if the transformer has enough capacity. Two mechanical chimes on a 16V 10VA transformer is marginal; a 15VA unit such as the T1615 handles two, and a 30VA unit or the DH910.Can I keep separate transformers for each unit with a two-family button?Yes. Each button on a Lee two-family or three-family station is an independent switch with its own two terminals, and nothing on the plate connects one button to another. One.Why does my lighted doorbell button hum or not ring with an electronic chime?A lighted button passes a small current through its lamp and the chime all the time, which is what keeps the button glowing. Mechanical chimes with tone bars ignore that trickle..