It seems like I'm on a roll with the dimming, so I figured I would delve into the different fluorescent dimming ballast technologies. Dimming fluorescent fixtures was a great option when LED first came on the market. Fluorescent is the popular "Value Engineered" option when an end user was faced with the quote for an LED package. Fluorescent in some cases can dim just as well as LED, and can save energy when dimmed. Although it cannot match those LEDs that can dim to 5 or 0%. LEDs have dropped in price over the past few years, and the main problem with dimming fluorescent is that the dimming ballast is expensive. Many LED fixtures that have dimming already included are around the same price point, consume less energy, and do not need regular maintenance for lamp replacements. These are considerations that need to be made when designing a job to meet a specific budget.
Fluorescent Dimming Ballast Technologies
2 Wire Fluorescent
Requires a dimmed hot, and a neutral. The hot is dimmed with a forward phase dimmer.
3 Wire Fluorescent
Requires a dimmed hot, a switched hot, and a neutral. The hot is dimmed with a forward phase dimmer, but the power for the fixture is controlled by the switched hot.
4 Wire Fluorescent (0-10v)
Requires a non-dim hot, a neutral, and two low voltage inputs that receive a 0-10v signal. The power for the fixture is controlled via the non-dim hot. Many 0-10v drivers can not dim to 0%, and will be turned off via the non-dim hot to get to 0%. (See my post about LED dimming technology for more on the 0-10v technology).
