For this post, we will discuss the dimmable transformers used in halogen lighting. These are mostly found in under-cabinet applications. The transformer is used to convert the 110 Volt alternating current (the power supply to most North American home wiring) to a 12 volt direct current. The 12 volts applications carry fewer amps and allow smaller wires from bulb to bulb. These smaller wires are easier to manage and conceal in tight spaces.
48468 - Halogen Lamp Electronic Dimmable Transformer
To connect the transformer to the home power supply, connect the black and white wires to the house wires. Most house wires are also black and white. The black wire is the hot and the white wire is the neutral wire. If you are planning to plug this transformer into an outlet and connect it to a cord set (with plug), you will need to connect the black wire to the smooth cord that plugs into the thin blade of the outlet.
From the transformer, there is also a pair of red wires. They will carry the 12 volts to power the halogen bulbs. While the 12 volt DC current has a plus and minus side, the halogen bulbs to not have to tie to a certain side. (NOTE: If you are using this transformer to power 12 volt LED bulbs, you will need to keep the positive and negative sides consistent.) Also, remember the halogen bulbs must be rated for 12 volt circuit.
Most of these applications will have more than one bulb on the transformer, so you will need to keep the circuit organized where the + is on one side and the - is on the other.