Lights.com—Ceiling Light Fixtures
Ceiling light fixtures should not be too heavy because electric ceiling boxes in most homes are not designed to carry much weight. 10-15 pounds is acceptable and if the metal electric box is attached directly to a solid framing member, it can handle about 25 pounds. If you want a grand ceiling fixture, such as a large crystal chandelier, you could be hanging 50, 75 or even 100 pounds of gear overhead from an electric box designed for much less weight.
If you don't want to be worrying your new chandelier, find out how much it weighs first. If it is much heavier than a standard fixture, install special brackets and ceiling attachments to handle the extra weight. You can also opt to buy a lighter fixtures.
Securing Ceiling Light Fixtures
If not well attached and supported, hanging ceiling light fixtures can fall down in a natural disaster and with serious consequences. It is best to secure ceiling lights to supports using safety cables. Using a chain strap or a minimum 14-gauge wire to attach each of the light fixture's four corners to a nearby ceiling support is recommended.
Be sure to leave the safety cables slack and they should not support the weight of the lights under normal circumstances. If your ceiling light has a cover, keep it from falling during an earthquake or windstorm by fastening it to the fixture itself or to the permanent structure. Also, pay special attention to the fluorescent lights as installing plastic sleeves over the fluorescent light tubes will keep the glass from scattering if they break. Teflon fluorescent lights, which are shatter resistant, are also a great alternative in ceiling lights.