When choosing an illuminated switch you have to decide if your application requires a dependent or an independent lamp(s). Not only does it make a difference in when and how it lights but also in how many terminals it adds to the bottom of the switch. We will discuss the differences in both of these options.
A dependent lamp(s) is a lamp that is dependent on the circuit. Basically all that means is that when the switch is "on" it is lit. So if you have a simple on-off switch with one dependent lamp you only have the option for the lamp to be on when the switch is in the "on" position. Otherwise the circuit is open and the lamp will not light. A dependent lamp (1) adds one more terminal to the bottom of the switch base.
An example of a switch with a dependent lamp: V1D1B60B-00000-000
An independent lamp is when the light stays on all the time when power is sent to the switch regardless of whether it is in the "on" or "off" position. A lot of marine dashboards and vehicle applications use independent lamps so that when it is dark the switch will illuminate so that you can see them to turn it on. An independent lamp (1) adds two terminals to the bottom of the switch base.
An example of an independent lamp: V1D1160B-00000-000
You can also use a combination of the two in a switch for your application. That way one will always remain lit as long as there is power to the switch and the other will light up when it is in the "on" position so that you know the switch is in use.
An example of the combination: V1D1JHCB-00000-000
In the example the red is lit all the time indicating the switch is off but also showing the location of the switch in the panel and the green is only lit when the switch is on. The combination of the two adds a total of 3 terminals to the bottom of the switch base (in a standard configuration).
While it may be confusing or if you need more assistance in helping to configure the switch you require for your application our knowledgeable and friendly sales staff is always here to help.