An intermediate switch is a three way light switch. It is used when you have three or more switches controlling one light, the middle switch needs to be an intermediate light switch.
The typical example of this is on a landing in a house, when perhaps there is a switch at the bottom of the stairs, one at the top of the stairs and one at the end of the landing. On this circuit you would need the middle switch (eg the one at the top of the stairs) to be an intermediate switch.
This can be continued for multiple switches, so it applies to three or more switches. Think of a shared landing in a block of flats for example.
An intermediate switch is only used on certain occasions so first of all let's cover the other switches and when you'll need them.
It is worth noting that all of these switches look the same from the front, although they do look different from the back.
There are two types of 'normal switches' a one way and a two way switch.
A one way switch is used when you only have one switch for a light.
One-way Switch diagram
Two way switches can be used when there is only one switch for a light, as a substitute for a one way switch. Click here to read more about what is a two way light switch.
They can also be used when there are two switches for one light. The classic two examples of this are either when a room has two different entrances (like a through room) or a light for a landing, where there is a switch at the top of the stairs and one at the bottom. People often mistakenly order an intermediate switch for this. While an intermediate switch will work for this, it is certainly not needed and a two way switch will do the job perfectly.
Two-way Switch Diagram
And so onto the intermediate switch.
This is a very versatile switch and can be used for most lighting situations, but in reality it is more expensive, so you would normally only use it when needed. That is when you have three switches controlling one light, then the middle one needs to be an intermediate switch (the others need to be two way).
Intermediate Switch Diagram
An intermediate switch can be used as a one way or two way switch (but is more expensive, so would not normally be used for this).
A two way switch can be used as a one way switch or a two way switch. They are often used as both. In fact many electrical retailers (including Socket Store) don't sell one way switches as the price difference is insignificant and the two way will do the job for both.
A final question we often get asked. Why does it cost so much more? Well the answer's simple. It is a more complicated circuit (see the illustrations above) and therefore costs more to manufacture.
We hope that all helps, but of course if you are still unsure give us a call on 02920 004887 and we'd be happy to answer any of your questions.