When creating a new Revit family based upon the Electrical Equipment template, there is a parameter already within the family named Voltage. This is a system parameter which is predefined in the template and cannot be removed. By default, this is a Type-based parameter. You cannot simply edit the parameter and change it from Type to Instance as can be done with other parameters. However, it is possible to change it to Instance-based and this article will show you how to accomplish that change.