3 Signs It’s Time for an Electrical Ballast Replacement

Are your fluorescent bulbs on the fritz? If you’ve recently been hearing a strange, loud buzzing sound every time you flick on the lights, or are experiencing inconsistent lighting levels, there’s a chance the bulbs themselves aren’t to blame.

Many large corporate lighting panels or office lamps operate with a little help from an electrical ballast. This device regulates the distribution of energy across your lighting fixture, working with a load to limit the amount of current in an electrical circuit.

That means that when your ballast starts to go, your lights have nothing to regulate the current that travels through your bulb’s tube. Eventually, when you flip the lights on, your bulbs will overload and fry!

But if you catch a faulty ballast before it’s too late, you can save yourself the hassle of purchasing all new bulbs. Here are a few signs that your ballast might need replacing:

1. Know if your light even requires a ballast.

This is a great place to start your troubleshooting journey. Not all lights require a ballast to function, so make sure this is your problem. 

Incandescent and halogen bulbs, for instance, aren’t ballast-dependent— and LED bulbs don’t require one either.

Then there are the light bulbs that have a ballast integrated inside, which can’t be replaced separately.

Many fluorescent bulbs, for example, have an internal ballast. Compact fluorescent bulbs (CFLs) often have one integrated too— just like some HID lights often do— but not always. 

Single bulbs with an integrated ballast need to be replaced just like any other bulb when they die or act faulty (you’re not going to tear apart the bulb itself to replace an internal mechanism). However, larger light fixtures may operate with the help of an external ballast.

Commonly, the long strips of T12 or T8 fluorescent lights on your business’s ceiling have one shared electronic ballast, which can be replaced without necessarily needing to swap out the light strips (if you catch the problem before the ballast dies and burns out the bulbs, of course).

Some older parking lot high-intensity discharge (HID) lights also use a ballast, though many modern fixtures use high-efficiency LEDs now instead. 

2. Look for warning signs that the ballast is failing.

After you’re sure you have a ballast, it’s time to investigate.

Typically, if just one CFL bulb is out, try replacing the tube. If you notice that any of these signs affect an entire section of lighting, it might be time to test your ballast:


If you hear a strange sound coming from your bulbs or light fixture, like a buzzing or humming noise, that’s often a sign your ballast is going.  It’s struggling to maintain the current and causing audible voltage regulation problems.

Dimming or flickering

If your bulbs are very slow to reach full brightness or strobe periodically, there may be a problem beyond the bulb. Water-damaged or faulty ballasts often struggle to regulate current. 

No lights at all 

If your bulbs won’t turn on, there’s a fat chance they all went at once from natural causes. Your faulty ballast might have burned them all out!

Changing colors 

Your lights should consistently shine at the same brightness and hue. If you notice a variance in color, your ballast might be on the fritz and surging sporadic voltage levels to your bulbs.

3. Check the ballast itself. 

Oftentimes if your ballast is slowly huffing or completely shot, it’ll be very obvious. Be sure to turn off your fixture’s circuit breaker in your electrical panel before tinkering. Remove the cover over your light and the bulbs themselves before examining your ballast for:

Swollen casing 

This is something you’ll see before you even take the casing cover off. If the plastic is bulging, your ballast is a goner. Very likely, energy overloaded it and damaged the box.

Burn marks. 

Sometimes you have to crack the ballast open to see internal damage. If you see burn marks inside the device or on wires, replace it. It couldn’t handle the current and overloaded. If this is the case, you may need to replace your bulbs too.

Water damage

Is there moisture inside of your panel or the ballast? This is probably what fried the device.

Leaking oil

If you have an older magnetic coil ballast, it could be leaking oil and malfunction. Carefully clean the area before replacing it. 

Professional Ballast Testing & Replacement

Still stumped?

Instead of standing on a ladder and poking around live wires, give the SWFL Electric team a call. We’d be happy to test your ballast and get you a speedy replacement.

Message or call us at (239) 935-5892.