It’s now illegal to manufacture certain sizes of regular incandescent 120V lamps, though you can still buy incandescents in various sizes and in energy-efficient versions. One advantage of incandescent lamps is dimmer selection is simple; you just need a dimmer of sufficient rating for the load. That isn’t an advantage with low voltage (LV) lighting circuits.
Yes, you can put LV lighting on a dimmer. And doing so will, as it does with incandescent lighting, extend the lamp life. But if your lamp (whether LV or 120V) is a halogen type, you need to activate the halogen cleaning cycle periodically. And the only way to do that is to run it at full voltage. You can use a more complex dimmer, or just add this task to the preventive maintenance schedule.
But selecting any dimmer for an LV system carries a caveat that you don’t have with 120V incandescent systems. The problem is you must select a dimmer that works with the type of stepdown transformer your particular LV system uses. There are two types:
- Magnetic transformer. It uses a copper wire wound around a steel core, making it an inductive load. And that steel core makes it big and heavy.
- Electronic transformer. It uses electronic circuitry, making it (in net) a capacitive load. Because it doesn’t have that steel core, it can be put into a relatively light, compact package.
Adding a dimmer is almost never a bad idea, but match the components.