How to Find the Bad Bulb on Christmas Lights from Mr. Electric

It’s the universal condition: every holiday season, homeowners across the country dig boxes of holiday decorations out of their attics or basements only to discover miles of burned-out Christmas lights! When you’re hanging your Christmas decorations and preparing for guests, the last thing you want to worry about is broken string lights. Let Mr. Electric help you find the bad bulbs on your Christmas lights so you can concentrate on the fun stuff!

Or, save yourself the time and hassle by scheduling an appointment for our holiday light-hanging services. You deserve a totally stress-free holiday!

What You’ll Need to Fix a String of Lights

Grab your dead strings of lights and a few simple tools, and you will bring those lights back to life in no time.

• Voltage detector or Christmas light tester tool
• Safety glasses
• Outlet
• Replacement bulbs at correct voltage rating

Troubleshooting Christmas Lights

The trick to string light repair is to eliminate easy solutions first, and then move on to trickier ones. First, figure out if the problem is just a single bad bulb or a wiring issue.

Before you start looking for a burned-out bulb, check for the following:

• Loose bulbs
• Damaged or frayed wires
• Damaged outlets or electrical plugs

If you aren’t sure whether the problem is a malfunctioning outlet, you can check it with a multimeter.

Finding Bad Bulbs on Incandescent Christmas Lights

Incandescent string lights are wired in a series. That means the electricity must pass through each bulb to complete the circuit—and a single bad bulb can make the whole string go dark. Larger light strings may contain two circuits. In these cases, you may notice that only one section of the string goes dark.

The easiest way to find faulty bulbs on incandescent Christmas lights is with a Christmas light tester. Simply bring the light tester close to each bulb. The tester’s indicator will light up when it’s near a functioning bulb.

If you have a non-contact voltage detector, bring the detector close to the wire section between each bulb to test for voltage. The dead section of wire will be the section after your bad bulb.

If you’re sick of your incandescent bulbs burning out, consider switching to LED lights—especially if you’re concerned about light safety. LED bulbs use less energy, produce less heat, and last longer.

Finding Bad Bulbs on LED Christmas Lights

Many LED Christmas lights are made without removable bulbs, so the circuit won’t fail if a single bulb breaks.

If you have LED Christmas lights with removable bulbs, the troubleshooting process is similar to incandescent bulbs. Starting at one end of your strand, or in the dark portion of your strand, use your voltage detector or light tester to locate the faulty bulb or dead length of wire.

If you don’t have any voltage detectors or other tools but you do have a replacement bulb, you can go down the whole length of the string and switch out each bulb, checking to see if that solves the problem each time. This approach takes patience, of course!

How to Replace Christmas Light Bulbs

Make sure you have replacement incandescent or LED bulbs in the correct voltage rating and color. Unplug your lights before removing or replacing any bulbs. Carefully screw in the replacement bulbs and plug your lights back in. If you have replaced the bad bulbs on your Christmas lights but you still experience problems, the issue may be bad wiring. Consider replacing the lights at this point.

Running out of time before the big holiday party? Expert electricians are just a click or call away! Call Mr. Electric at (844) 866-1367 or schedule an appointment online.