Change System Type of family

Hi Everyone,

I am really new to dynamo. I understand the basics of how it works but I am struggling making anything that works. I am attempting to create a script with electrical conduit. I would like to be able to select a run of conduit and change the system type parameter from a list I have. Does anyone have any suggestions on how to approach this. I tried to attach the preliminary script I have to the post but it does not seem to be working. I would really appreciate any help on this.