What is the Voltage selector switch?

We need a little more information to answer this correctly. What piece of equipment has this switch? Let me take a guess since you posted this in the computer forum.

On the back of most desktop PCs there is a red switch showing "115" or "230." In the US, this should be set to "115." That's because we have what it typically referred to as "110 volt" power to our homes and businesses. In Europe, they use 220 volt typically so the switch would be set to "230."

IMPORTANT: Don't touch this switch if your equipment is working properly. If think you need to change it before operating the equipment, please contact an electrician or the manufacturer or where you bought the item.

For a more detailed answer check out External Voltage Selector Switch (http://www.pcguide.com/ref/power/sup/partsSelector-c.html).