Our easy to understand doorbell wiring diagrams cover the most common configurations of low-voltage wired combination doorbells (front and rear chime in a combined unit) and single bell / buzzers.
Single Chime + Single Push Button
- Ignore the rear terminal.
- The same wiring diagram applies to a single bell or buzzer (non-combination chime).
- Use a NuTone C905 transformer, or equivalent, with a rating of 16V – 10VA. These are standard specs for most single 2-note chimes and the type of transformer supplied in contractor grade wired door chime kits (ref. parts list below).
Single Chime + Two Push Buttons
- Add a rear, side, or garage entry door button in addition to the main front entry door button.
- The same transformer specs and basic wiring apply as used in a Single Chime + Single Push Button setup, with the addition of another push button and utilizing the rear terminal on the transformer.
- The rear chime is only a 1-note chime. This creates a slightly different sound from the front 2-note chime to indicate which button is being triggered. This is achieved by a bumper inside the chime – above the “rear” chime pin – that prevents the top chime bar from being activated
See also: Electrical Tool Kit - The Essentials
Two Chimes + Single Push Button
- Strategically placing two or more chimes in a dwelling assures that the doorbell sound is heard throughout the entire residence.
- Powering 2 chimes simultaneously requires a larger transformer, e.g. NuTone C907, or equivalent, with a rating of 16V – 30VA.
Two Chimes + Two Push Buttons
- Combine the information given for Two Chimes + Single Push Button and Single Chime + Two Push Buttons.
|Doorbell Button||Basic or Lighted||Shop Now|
|NuTone C905 Transformer or Equivalent||16-volt, 10VA||Shop Now|
|NuTone C907 Transformer or Equivalent||16-volt, 30VA||Shop Now|
|NuTone C909 Tri-volt Transformer or Equivalent||8, 16 or 24-volt 20VA||Shop Now|
|NuTone C915 Transformer or Equivalent||16-volt, 10VA (Fits in single electrical box)||Shop Now|
|20 gauge 2 conductor Wire (20/2) †||Sold By-the-Foot or Roll||Shop Now|
|18 gauge 2 conductor Wire (18/2) †||Sold By-the-Foot or Roll||Shop Now|
|Complete Door Chime Kit||Wire not included||Shop Now|
Important – Applies to All Wired Doorbell Systems
- Class 2 Circuit: Class 2 circuits power temperature controls, doorbells, door openers, lighting controls, irrigation controls, communications accessories, etc., in many types of occupancies. Class 2 and 3 circuits are defined as the portion of the wiring system between the power source and the connected equipment. Because of the power limitations of Class 2 circuits, many consider them to be safe from a fire initiation standpoint and to provide an acceptable level of protection from electrical shock.(ref. doorbell parts section below for more information).
- Polarity: There are two types of poles (positive and negative). This represents the electrical potential at the ends of a circuit. Polarity only applies at the power side of the transformer where there’s a neutral (always white) and a hot (commonly red or black, but can be any color). But neither the push button nor the transformer terminals are polarity specific (have a negative and positive), in which case the red or white wire can connect to either terminal of these components.
- Annunciator(Bell) wire vs. Thermostat wire? Either is fine. Bell wire comes as separate individual wires, while thermostat wire has a jacket to keep the wires bundled together. Depending on the layout of your home and location of doorbell components, choose if individual or bundled wires work better (ref. single doorbell button wiring diagram).
- WARNING: Electrical Hazard. Before beginning work, turn power off at the breaker panel or fuse box to avoid injury. For safe wiring practices, consult the National Electrical Code and your local building inspector, or a licensed electrician.