It is called the electric cross over. There will usually be a single cross over from the side of the home where the panel box is to the other side. Some builders provide a hard wired cross over, where a wire is brought from under one section to the other into a junction box. Some times this is found in a junction box under the home. Other times this can be found in the wall of the home.
Start by looking near the center line of the home on the front and back walls (thinking of the home the way it goes down the road... the short sides). Look for a blank electrical cover plate. You may find the cross over connection in there. You might even find it in a box located on the center line in a closet or under a sink.
Other builders use what is called a quick disconnect, which is a plug together system that you will generally find recesses in the wall between the two sections, or hanging below the centerline.
Find a local dealer who carries your brand of home. Most of the time the eclectic systems are not married together when the homes are on display and you can probably look under the home to see how your builder handles the crossover. If that is not possible call the local dealer him for the contact information for the contractor who sets his homes. They would be most familiar with the systems for your particular home.