Replacing Light Fixtures: A few things to consider
What is the maximum wattage your fixture can accept. Your new fixture should not exceed this total wattage. Failing to do this could result in a fire. Wattage is not a measurement of light, it is a measurement of energy (electricity). The measurement of light (brightness) is called lumens.
Canopy (back plate) Measurement
The canopy (back plate) of your replacement fixture should match in size (at least as big) to the one you are replacing.
It's not a bad idea to document the existing fixtures wiring. This makes wiring the new fixture easier. Most people have cell phones with cameras, so it's easy to snap a couple of pictures of things before you start.
Weight of the Fixture
If you don't replace the junction box, you'll need to choose a new fixture that is the same weight, or lighter, than your current fixture.
For more information about replacing your light fixtures, contact Pacific Lamp.