How to wire a two-way switch to control two lighting bulbs.

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During our electrical household installation, there are different types of switches used in controlling lamps that serve different purposes. You being an installer or the engineer in charge, are always expected to note the types of switches to use and why they should be used. Like differentiating between a 2-way switch and a 1-way switch.

A 2-way switch is one of the types of switch/control used in electrical installation. This particular post only focuses on this type of switch ( 2-way switch). We shall discuss its internal connection, the external connection of the switch, and how we can run the connection on our installation.

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what is two-way switch wiring

A 2-way switch controlling one lamp is switch connections that allow us to control one lamp from two different places. Just like a switch controlling a Lamp on the steps or staircase of the house. You will always notice at the light is controlled through two different switches. Meaning when we ON the light at one end, we can equally OFF or ON it at the other side.

what is the importance of two way switch?

We always Install this type of switch control on our building/house so that we will have access to control our light bulbs from different locations. Let’s say for instance, when entering the room during the night, you can turn ON switch light at the door side to see in the room, and when you went bed for sleep, you can equally OFF the same light bulb from another switch near the bedside.

Another instance is when climbing the steps of an upstairs, on the down floor, you ON a switch to see the steps. So on reaching the final step you can decide to off the same light from another switch installed at the last step.

The functions of a 2-way switch in our work are numerous. You hardly do an electrical house installation without installing a 2-way switch on it.

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Internal Construction of 2-way switch.

To proceeds on how we can wire a 2-way switch, is very important to know how this switch is constructed internally and the working principle.

The 2- way switch can also be called Single Pole Double Throw SPDT. This switch has three terminals for connection which are labeled COM, L1, and L2.

On the internal connection of the switch, it was design in such away that the COM is either connected to L1 or L2.

when the switch is in one position is either that the COM is connected to L1 or L2 but the two L1 and L2 can not be connected together at same time. For instance, if the switch is switched ON then the COM pole then goes in contact with L1, then when the switch is turned OFF, the COM pole discounts from L1 and connects to L2.

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How to wire a two way switch to control a light bulb.

Now that we have known how the switch operates internally. The task we have now is to know how we can connect this switch to be able to control our electrical bulbs from two different positions.

There are two different ways we can use to wire the 2- way switch. All the different methods work perfectly ok. Learning the two methods is good so that you can practice with the one you find easy.

In wiring a two-way switch, we should always have in mind that only a positive wire goes through the switch. While the neutral line goes direct from the source to the lamp holder.

First method of how to wire a two way switch.

The diagram below is a guide to help connect a 2-way switch that can control a light bulb from tow different positions.

How to wire a two way switch
2-way switch wiring diagram

Connect your circuit as it is on the above diagram.

  • The red or live wire from the source is connected to the COM of one of the switches, while the black/neutral wire runs directly to the lamp holder.
  • From the second switch, connect from COM to the lamp holder.
  • Connect the L1 of the first switch to the L1 of the second switch and then, connect the L2 to the L2 of the second switch.

Second method of wiring 2-way switch.

There is an alternative method that can be used to wire the 2-ways switch. Is either the first method or this one can be used to wire the switch. But the two method works perfectly.

The second option can be achieved through the following steps;

For better understanding, use the diagram below when wiring the switch.

How to wire a 2-way switch
Wiring of 2-ways switch.
  • Run a connection from the source to the L1 switch and tap from the L1 and connect to the L1 of the second switch.
  • Run a connection from the COM of the first switch to the COM of the second.
  • Connects the L2 of the two switches and taps from the L2 to the lamp holder.

Circuit Examples for two-way switch connections.

Two way switch wiring diagram at ON position.

below is a diagram of two way switch that shows how the current flows on the switch when it’s turned ON. It goes from the live wire to the first switch, to the second switch, and completes the circuit. And the lamp is then turned ON. We can turn OFF/ON the lamp from any of the two switches.

Two way switch wiring diagram at ON position
two way switch in ON state

Two way switch wiring diagram at OFF state.

Two way switch wiring diagram

In this position, one of the switches is turned OFF and the light goes OFF and you can see the circuit is no longer complete. At this point, the lamp can be turned ON from any of the two switch.

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2 thoughts on “How to wire a two-way switch to control two lighting bulbs.”

  1. Pingback: How to wire an intermediate switch for staircases and hospitals. - Sparkrey

  2. Pingback: how to control a light switch using a one-way switch(SPST). - Sparkrey

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