Normally, mounting a new ceiling light fixture means that you simply attach the mounting screws on the new fixture to small threaded screw holes on the overhead electrical box. It could not be simpler, especially when you are simply swapping out an old fixture and installing a new, up-to-date light fixture.
Tip: Remember, you cannot hang a heavy ceiling fixture, such as a chandelier, directly to an overhead electrical box. You must instead first mount a cross-bar mounting strap to the box (if there is not one already present), then use the mounting strap's threaded opening to hang the heavy light fixture with a sturdy threaded metal nipple.
But with drop light fixtures, such as a chandelier, the heavier fixture is supported by a threaded nipple, one end of which is threaded into a female threaded opening on the ceiling box mounting strap, with the other end of the nipple threaded into a similar fitting on the base of the light fixture. The problem, though is that the threaded mounts are often of different sizes—3/8" threads in the ceiling box mounting strap, and a different size, such as 5/16", in the mounting nipple for the chandelier.
What Is a Hickey?
A hickey is a small piece of hardware with two female thread openings that allows you to make this transition using two short threaded nipples of different sizes. The top side of the hickey is threaded onto a short nipple connected to the ceiling box, while the chandelier's nipple is threaded onto the lower threaded opening on the hickey.
Tip: Specialty lighting stores will stock many unique parts, including hickeys with various thread sizes. At these retailers (as well as online) you can buy just the single part you need. At big box home improvement stores, look for ceiling fixture mounting kits that include all parts for mounting a drop light fixture. The kits will include mounting straps with screws, as well as the hickey fitting, and sometimes short threaded nipples as well.
The hickey also provides a space to route the chandelier wires for connection. The light fixture's wire leads can be threaded through the nipple and connected to circuit wires with wire nuts. Because the chandelier is firmly supported by the nipples threaded into the hickey, this makes for an easy hookup of the electrical connections, with both hands-free to do the work.
After the connections are made, the wires are tucked up into the ceiling box, and the chandelier cover plate is lifted into place and secured to the ceiling box.
Tip: When replacing a standard ceiling light fixture with a heavier fixture, such as a chandelier, it is important that the ceiling box is securely anchored and up to the task of supporting the heavier load. When in doubt, the ceiling box should be reinforced with blocking installed between joists to ensure a solid base.