Twelve-volt indoor lighting systems have many applications in the home, such as accent lighting, safety lighting and regular lighting. Using a 12-volt system is inexpensive due to the system's low power consumption. Most 12-volt systems use light-emitting diodes (LEDs) as the light source. Over the last few years LEDs have become more prevalent in the household due to 12-volt lighting systems. Eventually LEDs and florescent lighting will become the primary sources of light in homes.
Determine where the 12-volt lighting will get its AC power. Shut off the power to that circuit and test for voltage before beginning work. Using an existing ceiling light fixture is best due to easy access.
Decide on a location in the attic for the transformer unit. The transformer unit will step down the 120 volts to 12 volts and convert it from AC to DC. Mount the transformer to a joist. Remove the existing light fixture and pull the black and white wires out of the junction box. Connect the black and white wires to the transformer input side using plastic twist caps. Route the low-voltage output wires down into the junction box.
Connect the input wires of the new low-voltage light fixture to the output wires of the transformer through the junction box. Secure the connections using plastic twist caps. Push the wires back into the junction box and secure the light fixture using the screws provided with the new fixture. Turn the power back on, and test the light.
Test for voltage before beginning work.