How Do I Know if My HID Ballast is Bad? – Common Signs


Written by

Thomas Carter



Marcos E. Williamson

how do i know if my hid ballast is bad

How do I know if my HID ballast is bad? There are a few different signs you can look for. One of the most common ones is that your lights will flicker or turn on and off intermittently.

They might appear dimmer than usual or take longer to reach full brightness as well. If you notice either of these signs, it is likely that your HID ballast is beginning to fail.

It is important to have it checked and replaced as soon as possible to ensure that your lights are functioning properly and providing adequate visibility.

But there are other signs of a bad ballast that you should remember, and we will uncover them in the blog post here. Read until the end to learn everything you need to know about bad ballasts!

How to Know if Ballast is Bad?


If you suspect that an HID ballast is defective or experiencing issues, there are a couple of signs to look out for.

First, see if the bulbs are flickering or failing to turn on despite being powered up. This is likely a case of your ballasts acting out and failing to deliver stable currents.

Damaged ballasts may also result in overheating of the bulbs as well as dimming or uneven lighting outputs. The colors of the beams may also change, which is a sign a replacement is necessary.

If your system produces sparking or other electrical sounds around the ballast, it may also be an indication of damage. Other weird noises like humming or buzzing, particularly when your HID bulbs are not on, can indicate that they are encountering a voltage regulation issue.

If you are having to replace your fuses more regularly than usual, there is a good chance that the ballast is no longer able to regulate the voltage properly, causing it to ramp up the current in the system. In this case, you have also got yourself a faulty ballast.

In addition to performance indicators like HID ballast not working and HID ballast making buzzing noise, you can check if a ballast is bad by looking at its appearance.

Some bad ballast symptoms are clear right off the bat, such as those from the casing/housing. Its shape may be distorted or damaged as a result of voltage overloads.

Going further than the casing/housing, when you open the ballast up, you might find burns from a voltage surge or blown capacitor. There might also be traces of moisture or oil, which definitely point to HID ballast problems.

How to Check a Bad HID Ballast


You can use a multimeter to test the HID ballast. Don a pair of safety gloves, grab a screwdriver, and follow the steps below.

  1. Switch off your lights. Wait a bit for the ballast to release any stored current.
  2. Remove the ballast’s casing/housing using a screwdriver.
  3. Turn the multimeter on and set it to the highest resistance setting.
  4. Put the black probe on the white wire and the red one on the blue, red, and yellow wires.
  5. Get the reading. If it says OL or indicates max resistance with a 1, your ballast is good.

The multimeter will not move if you have a bad hid bulb. It may also show that there is no continuous circuit.

Another simple way to know if a ballast HID stopped working when HID lights won’t turn on sometimes is by switching out the bulbs in the light fixture. You know that it is the ballast’s fault if you put in new bulbs and the problems you found beforehand still persist.

Common Reasons for HID Ballasts Going Bad


In most cases, a ballast goes bad because of exposure to extreme temperatures or moisture.

  • Temperatures: High temperatures can drive ballasts to overheat and burn. In contrast, low temperatures can keep them from starting.
  • Moisture: The ballasts can become corroded, and therefore, faulty.

That is why it is important to be mindful of your ballast installation. You need to choose a location that is not too hot or too cold. It should also have low humidity levels and typically dry.

Speaking of location, HID ballasts should be away from external elements.

Debris accumulation is another reason ballasts become faulty. So, it is essential that you make it a habit to clean your ballast once in a while.

To extend your ballast’s lifespan and keep it from going bad, you must also ensure that there are no loose connections, which can cause it to switch on and off, and, thereby, result in premature failure.

Frequently Asked Questions (FAQs)


What happens when a ballast goes bad?

When a ballast goes bad, regardless of whether it is a ballast car or a ceiling fluorescent fixture, the light will be affected. It might not come on, dim, change colors, or flicker. In addition, it may emit weird noises, such as humming and buzzing. These are the common problems with HID lights operating on bad ballasts.

If you examine the ballast physically, you might find that its casing/housing is swollen. You may also come across burn marks, moisture, or oil leaks.

What to do when your ballasts do not work?

Ballast still not working? This means that you will have to go ahead and proceed with an HID ballast replacement. Here are the general steps you should take:

  1. Turn off the electricity to your fixture.
  2. Take the casing/housing off of the ballast using a screwdriver.
  3. Disconnect all the wiring that connects to the ballast and take the device out.
  4. Mount a new ballast into the same location with mounting nuts.
  5. Connect ~0.5 inches of the new ballast wiring with the old one, making sure to match the colors and use twist-wire connectors.
  6. Put the cover back on to reassemble the fixture.
  7. Test the fixture by flipping the electricity back on.

*Note: Make sure that your new ballast matches your old one in terms of amperage and voltage. It can be a bit pricey, but rest assured that it is a worthy investment.


How do I know if my HID ballast is bad? As written above, there are certain signs that can indicate a bad ballast, such as unusual noises or physical damages. You can verify whether your HID ballast has indeed gone astray with a multimeter. Simply follow the steps that we have provided above.

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