When the transformer is plugged into a 115v outlet, 12 volts are provided at output. The junction splice is pounded into the first tape run. The two nails protruding from the bottom make electrical contact with the tape and holds the splice in place. The lead in wire is plugged into the junction. As subsequent tape runs are added, the 12 volts automatically passes from one tape to next. After all runs are in place, outlets, and fixtures may be installed. Lighting kits and extras are available in different sizes depending on the number of rooms in your house. Check the Dolls house Lighting section for further information, prices and to order.