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Ballast - Lighting Capacitors

Ensure your HID lighting fixtures are operating at full brightness by replacing old capacitors with one of our Aerovox dry or oil filled HID capacitors in stock and ready to ship.


HID capacitors are available in two types: dry or oil filled. For general lighting applications including ballast kits and sign lighting, choose a dry capacitor. These HID capacitors operate in temperatures up to 221 degrees Fahrenheit. Oil filled capacitors are used in applications that require higher power and voltage, such as stadium, horticulture, and industrial lighting. Operating in temperatures up to 194 degrees Fahrenheit, these light capacitors use oils (such as epoxidized soybean oil) to fill air voids and remove heat from the capacitor windings.

How to Tell Which Capacitor You Have

If you are not sure which type of capacitor you currently have in your fixture, take a look at the case and how the capacitor connects to the ballast. Dry capacitors have insulated wires coming out of the top and a plastic case. Oil capacitors have a metal case and connect using terminals.

Tips for Maintaining Your HID Capacitor

Preforming regular maintenance on your HID capacitor will help identify problems early. Use a multimeter to test the capacitance, or the amount of electrical charge the capacitor can hold. Replace the capacitor if the readings are significantly lower than what the capacitor is rated for. Always check the capacitor connections to make sure they are still attached. Loose connections can cause the capacitor to fail. You should also look for bulges and signs of the dielectric leaking. Avoid installing capacitors in high vibration environments. Vibrations can cause an HID capacitor to eventually fail due to malfunctions in heating and end termination resistance.

How Capacitors Work

Capacitors are made with two electrical conductors, called plates, which are separated by a non-conducting insulator called a dielectric. One plate builds a positive charge while the other builds a negative charge, creating energy that is stored in the dielectric. The energy is released in a strong burst when HID lighting ballasts begin to start the lamps. This helps regulate the voltage and current going to the lamps and also helps prevent flickering.

Not sure if you need a dry capacitor or oil capacitor? Get help from one of our lighting experts by calling 1-800-624-4488 today.