2 wires on the negative side. On the McCulloch H7 kit I installed last week, the wires do go directly into the back of the bulbs, but have weatherized connectors that plug into the ballasts. So, you can fish the individual wires through the clip prior to plugging them into the ballast. I didn't have to take the clips off, but it is a snug fit around the body of the bulb, however.

Also, don't forget to cut a little slit and run the wires through the rubber weather cover before you have everything connected... learned that one the hard way.