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Wiring a Doorbell System (NEC 2002)

By Warren Goodrich
Wiring a Doorbell System (NEC 2002)

Components of a Doorbell System

Doorbell Wiring is relatively simplistic compared to the rest of your home wiring, and works on a much lower "safer" voltage. Lower voltage also means that smaller wires can be used, 18 awg wire at either 2 or 3 wire cables (depending on your wiring choice). Like most things electrical, making it work means completing the circuit, without creating a dead short.

Doorbell power source: small transformer, power by 110 v , with an output of much smaller voltage usually at 16 volts.

Doorbell buttons: A convenient means of completing the circuit, located and mounted on the outside of an entrance to the home, may be used at one door or at 2 entrances. 2 wires are hooked to connectors of the button assembly, when the button is pushed, the contact is closed and thereby making an electrical connection between the 2 wires, and the connection is broken when the button is released.

Doorbell Ringer/Chime: The sounding device that produces a ring, or chime or other type of sound when someone pushes the doorbell button. Some have a different ring/chime pattern depending on if the front or back door button is pushed.

Methods of Wiring

Please Note, that for very long runs of wire, you may need to increase from a 16 volt transformer to a 24 volt transformer to compensate for the voltage drop if experienced. In cases where 2 chimes (2 separate sounding units) are used (located in different parts of the house) and run off the same buttons/transformer, may also need to increase from a 16 volt transformer to a 24 volt transformer. A diagram showing how to add a second sounding unit is located after the 3 wiring option diagrams.

The 110v side of the transformer gets connected to a circuit that leads to the electrical panel.

The 16 to 24 volt side of the transformer is what is actually feeding the wires of the doorbell circuit.

NEVER CONNECT THE 110 V SIDE TO THE DOORBELL SYSTEM CIRCUIT !

Always read your documentation that comes with the sounding unit (chimes) for voltage requirements, these requirements for specific voltage may need to be increased for very long runs of wire to compensate for voltage drop or for use in multiple sounding devices on the same doorbell system.


Power source going directly to sounding device (ringer/chime), button wiring coming individually from each button to ringer/chime.

One wire from the transformer goes to the common connection screw of the sounding device, the other wire from the transformer gets connected to one wire going to button 1 and one wire going to button 2.

The other wire from button 1 goes to one of the remaining connection screw at sounding device, and the other wire from button 2 goes to the last remaining screw of sounding device.

Note you may want the front door to make a ding-dong at the sounding device and the back door to make just a ding at the sounding device. If these sounds are reversed then just switch the wire on screws 1 and 2. The black and red wires in the diagram are for illustration purposes, your wires may be a different color. This method uses 2 wire cables.


Power source going directly to sounding device (ringer/chime), button are looped from one button to the next on a single cable and all button wires go to the chime on the same cable.

One wire from the transformer goes to the common screw of the sounding device. The other wire from the transformer gets connected to one wire going to the buttons. That wire gets connected to one screw on each of the doorbell buttons.

This method uses a 3 wire cable going from the sounding device to the buttons. Of the remaining 2 wires in the cable going from the sounding device to the buttons...At the sounding device , one wire goes to connection screw 1 and the other wire goes to connection screw 2.

At the buttons, one of the remaining wires gets connected to the remaining screw of button 1 and the other wire gets connected to the remaining screw on button 2.

Note you may want the front door to make a ding-dong at the sounding device and the back door to make just a ding at the sounding device. If these sounds are reversed then just switch the wires on screws 1 and 2.

 


Power source gets looped to the door buttons and onward to the doorbell sounding device (ringer/chime) all wires power and button feeds arriving at the sounding device in the same cable.

One wire from the transformer is connected to one connection screw of each doorbell button. The other transformer wire continues on until it gets to the sounding device where it gets connected to the common screw.

A 3 wire cable is used, and of the remaining 2 wires - one wire gets connected to the remaining screw of button one. The last remaining wire gets connected to the remaining screw on button two.

At the sounding device the remaining 2 wires gets connected to connection screws 1 and 2, 1 wire on each screw.

Note you may want the front door to make a ding-dong at the sounding device and the back door to make just a ding at the sounding device. If these sounds are reversed then just switch the wires on screws 1 and 2.


Using 2 Sounding Units (chimes)

To hook up a second sounding unit

  • Connect a 3 wire cable from unit one to unit 2,
  • Screw 1 wire from unit one goes to screw 1 of unit two.
  • Common screw on unit one to common screw of unit 2.
  • Screw two on unit one to screw 2 of unit 2.

Please note that in some cases you may need to replace the transformer feeding power for the doorbell system from 16 volts to up to 24 volts to handle the extra load of a second doorbell sounding device.


Using 2 Buttons on the Rear or 2 buttons on the Front

Option 1:

To add additional doorbell buttons, you may add an additional button on either the front door button or the back door button. In the wiring options above 2 wires are connected to each door button, To extend to another front button (or another rear button) connect another 2 wire cable to run from the 1st button to the 2nd button. Then connect one wire to each of the 2 screws (these 2 screws already have a wire on them as per the above diagrams, you are now adding a 2nd wire to on each screw to extend to the next button) at the add on button connect the 2 wires , one wire on each connection screw.

Option 2: (only if your doorbell system wiring has both wires of the transformer coming to the sounding unit first)

1. A new 2 wire cable is run from the sounding (chime) unit to the add on button.

2. At the sounding (chime) unit connect one wire of the cable to either screw 1 or 2 (depending if you want the new button to produce a ding-dong or just a ding. The other wire connects to the transformer wire that is NOT connected to the common screw of the sounding unit.

3. The other end of the cable at the new button , one wire gets connection to each of the connection screws.


Battery Operated Systems

Battery operated systems usually come with the wire used to connect the doorbell button to the sounding unit. They are operated by either 2 small batteries or a 9 volt.

Radio Controlled Doorbell Systems

Operated by a transmitter /receiver system. The doorbell button is mounted on the outside of the house close to the entrance door, and is powered by a battery. The sounding unit mounted on the wall inside is a receiver unit also operated by a battery. These units have range restrictions so be sure to read the documentation with the unit to determine the maximum range it can work with. Also note: batteries used on the outside of the house when used under extreme temperatures (particularly cold climates) may affect the life of the battery.

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