AMTRAK material handling cars

Why did Amtrak’s material handling boxcars need this electrical set up? Was it incase the boxcars were in front of the train between the locomotives are cars? Wait, I think I just answered my own question. Is this right?

http://www.railmerchants.net/amtrak-material-handling/AmtrakMaterialHandling/DSC00295_JPG.html

You did just answer your own question. [:D]