What is an Intermediate Switch? . An intermediate switch is a pivotal component in lighting and electrical systems. Designed for multi-way lighting circuits, it allows control of a single light source from three or more locations. This makes it an essential solution for large spaces like hallways, staircases, and conference rooms where convenience and efficiency are paramount.
Let’s explore the intricacies of intermediate switches, their functionality, and their significance.
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What is an intermediate switch?
It is a switch that is used in the middle of three way lighting circuit. That means that there are three switches controlling one light, or light switch circuit. The first and last switch on that circuit are two way switches. The middle switch is an intermediate switch. This ensures that the light can be controlled from all three switches at any time.
The typical situation for this within the home is stairs lighting. It may be necessary to control the light from three locations. The bottom of the stairs, the top of the stairs and on the landing or, as in the illustration, at the top, middle and bottom of the stairs. In this situation the middle switch needs to be an intermediate switch.
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Construction and Working
In an intermediate switch, there are four terminals by which it changes the flowing of electric current from one circuit to another (see fig 1 & 2) and is also known as Four-Way Switch (Three Way Switch in the UK & EU). It has the ability to ON and OFF the electric supply by two ways or control the single circuit from more than two places.
The four terminals of intermediate switch construction and its operation are shown in fig below where the 4 contact points may be known as A, B, C & D. When the switch knob is up, the terminal contacts of the intermediate switch connect terminal A with terminal C and terminal B with terminal D as shown in fig 1a. On the other hand when knob is down, terminal A is connected to terminal B and C to D then.
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In other words, When the knob of the switch is UP, then the vertical contacts are connected in such a way like AC and BD as shown in fig 1a). And when the knob is DOWN, then the Horizontal contacts are connected (i.e. AB and CD as shown in fig 1b).
Fig 2 shows the basic construction and working of Intermediate switch.
There is a little bit confusion about this switch due to regional codes i.e. the same DPDT (double pole, double throw) switch is labeled using different names e.g.
- UK & EU – IEC = It has 4 terminals for strappers wires to connect to the 2-way switches and known as Intermediate switch & 3-Way switch.
- US – NEC = It has 4 terminals for travelers wires to connect to the 3-way switches and additional ground terminal and known as 4-Way switch & Crossover switch.
The following figures illustrate the difference (which is not at all) between 3-Way and 4-Way switch.
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The following fig and gif shows how is a 3-way switch or intermediate switch wired with 2-way switches (according to IEC) to control a lamp from 3 places. (Alternatively, a 4-way switch working with 3-way switches to control an LED lamp from three different locations according to NEC)
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Application
Intermediate switch is mostly used in large premises & big rooms such as hallway wiring, Hostel wiring, hospital wiring, tunnel wiring, godown wiring and staircase wiring where different lamps are needed to ON/OFF from different places. Moreover, in a multistory building, the lamp at ground floor or in car parking shades can be controlled or ON / OFF from any floor by using an intermediate circuit.
Can you have 2 intermediate switches?
Yes, this setup can be expanded to more than threes switches. With a setup with four or more switches every switch in the middle of the circuit needs to be an intermediate switch. Once again the first and last switch on the circuit need to be two way.
Two Way Light Switching
As mentioned above, for an intermediate light switch to work it needs to be used in conjunction with two 2-way light switches.
Two way light switches, used together, enable you to switch a light or lighting circuit from two different locations, for instance in a hallway you may have a light switch next to the front door, and a second next to the kitchen. For this lighting circuit to work both switches would need to be two way light switches.
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One Way Switching
One way switching is where you only need one switch to control one light or lighting circuit. As this is a similar but more simple version of the two way light switch, we don’t sell specific one way light switch as it is as easy to use a two way light switch for the same function (just without connecting the L2 connection).
How to Control Light Point from Three Places using Intermediate Switch
In Fig 3, a lamp is controlled from three different places by using two, 2-way switches and one intermediate switch.
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Below is the same diagram (Fig 4) to control a light point (lamp) from three different places by using two, two-way switches and one intermediate with different symbols.
The following wiring diagrams show the installation of intermediate switches according to NEC and IEC where a light bulb is controlled from three different locations.
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Staircase Wiring using Intermediate Switch
Below is a given schematic circuit to control a light point from three different places by using two 2-way switches and an intermediate (or two 3-way and one of 4-way switch – US) in the middle of stairs.
The following wiring diagrams show the same configurations for both IEC and NEC codes.
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Controlling of Lamp from Five or Six Places using Intermediate Switch
In fig 5, a lamp is controlled from six different places by using two, 2-way switches and four intermediate switches.
Key Point: You may control a lamp from many different places by adding more intermediate switches such as in the middle of stair or in shared flats (when needed). Also, many other electrical appliances like fans, alarms, machines etc. can be controlled from different places by using an intermediate switch.
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Do I need an intermediate light switch?
If you have three or more light switches controlling one light, you will need at least one intermediate light switch. The two end switches will need to be two way switches. All the other switches, in between, will need to be intermediate switches.
Every range we manufacture comes with an option for an intermediate switch. Not only that, but we also have grid switches which can have any combination of intermediate and two way light switches on one plate. They are available in an option of one to four gang grid switches. We also have the same option with grid toggle switches.
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Frequently Asked Questions
What is the primary purpose of an intermediate switch?
It allows control of a light from three or more locations in a circuit.
Where are switches commonly used?
In large spaces like staircases, hallways, and conference rooms.
Can intermediate switches be used in smart homes?
Yes, modern versions often integrate with smart home systems.
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