How to test Christmas lights with multimeter?

Christmas lights are a great way to add some holiday cheer to your house. Whether you're looking for a string of traditional incandescent bulbs or the newer LED Christmas lights, testing it with a multimeter is important. Always check new lights before buying. If they don't light up, there's no point in putting them on the tree. Even one bulb can make your Christmas tree look ugly. Here I'll show you how to test Christmas lights with multimeter and how to fix them. Don't put those new LED lights on the tree until you read this!

Common Problems that can happen while Repairing Christmas Lights

If your strand of Christmas lights doesn't turn on when you plug it in, then it means that there is no power coming through. Many other problems can be the reason for faulty Christmas lights. You can test this by testing them with a good quality digital multimeter. If it doesn't read anything, then there is a good chance that the socket has gone bad. You can remove and replace that socket or use an electrical tester to check for power in the wire leading up to it. Let's discuss this in detail!

Damaged sockets

If you want to test a socket or bulb, the only safer option is a digital multimeter. Of course, you can also use a test lamp, but it will give you accurate results. To test any broken circuit, you just have to set the multimeter to Vac or AC option. After this, connect the red probe in the (V) jack and Black lead into the (Com).

You don't have to set the ranges if you're working with an auto-ranging multimeter. (If you need the best auto-ranging multimeters to check outlets, you can also find it on my blogs). The socket is perfectly fine if you see a closed circuit with 110V or 220V depending upon your country's standards. In case of zero or lesser voltages, check the main fuse box or just replace the bulb socket. Hopefully, it will work perfectly now.

How to test Christmas tree with multimeter


Faulty Bulbs

Most of the time it also happens that after checking the entire string you will not find see any fault. In such cases must look for a faulty bulb. After finding the faulty one replace the new bulb with the first bulb. If all the bulbs are also ok then use a voltage detector to check is there any power in the circuit. Bulbs are also old-fashioned and consume a lot of energy so must try to use led. LED lights are energy-efficient and cheaper as compared to bulbs.

Broken or non-functional fuses

A fuse saves your equipment from further damages. If the current from the rated limit exceeds, then the fuse will open. If you have a basic knowledge of electrical circuits, checking fuse is just a piece of cake. Because with electrical current between two points or with a continuity tester you can do it easily. There are two methods to test any fuse.

1st method: If you want to test your fuse in a live circuit, just the black test leads to ground, and the red test leads to fuse terminals. If the multimeter shows voltages, then your lights and circuitry are fine.

2nd method: If you want to check the continuity of a fuse, then first, remove any fuse from its respective slot. This can be done by using a fuse puller. Now, put your multimeter to the continuity option and put the black lead on one side and the red lead on the other side of the fuse. If the multimeter shows continuity, then it is ok. Otherwise, if you don't find any continuity or resistance, there is a short circuit or broken connection inside the fuse.

If you want to know more about fuse testing then you can read by blog on how to test fuses with multimeter.

Guide to test Christmas tree lights with a multimeter

Torn or damaged wires

This is the most common problem with Christmas lights. If any wire is damaged, then it can lead to many problems. So, if you find any cut or fray wires, then always replace them with new ones. You can easily do this by stripping the insulation off of both wires and twisting them together. If it doesn't solve the problem, then you have to replace them.

If the lights are either blinking or not working, there are some loose or damaged wire connections. You can check Christmas lights by the continuity function of a multimeter. First, connect the multimeter to any individual light, then check for continuity. If there is continuous reading of 0-1 ohm, it means that your wires are perfectly fine. If you find any damaged wire, then replace them.

Non-functional or damaged power plugs

If your power plug or socket is damaged, then it means the power cannot reach the lights. You can test this by using a multimeter to check for continuity in wires.

Dead bulb

To replace a broken bulb, you need special tools and replacement bulbs. If you don't have these tools, it's better to call an electrician.

Tools required to test broken Christmas lights

  • Repair manual
  • Multimeter
  • Cutter Plier
  • Screwdriver
  • Power plug
  • Fuses (number depends upon your requirement)
  • PVC electrical tape ( this electrical tape used to insulate the exposed wire)

Steps to Fix Christmas lights with a multimeter

Step 1

First, check your lights are plugged into the female socket properly. If you found out that the first socket is not powering up the Christmas tree then use the next socket.

Step 2

Now, remove any fuse from its respective slot. This can be done by using a fuse puller.

Step 3

Now, put your multimeter to the continuity option and put the black lead on one side and the red lead on the other side of the fuse. If the multimeter shows continuity, then it is ok. Otherwise, if you don't find any continuity or resistance, there is a short circuit or broken connection inside the fuse. Just replace it.

Step 4

If your light bulbs are non-functional, check every individual bulb's continuity using a multimeter. If you find continuity of 0-1 ohm, then it means you have to replace them.

Step 5

If the lamps are either blinking or not working, there are some loose or damaged wire connections. You can test each light wire by checking continuity with a multimeter. First, connect the multimeter to any individual light, then check for continuity. If there is continuous reading of 0-1 ohm, it means that your wires are perfectly fine. If you find any damaged wire, then replace them.

Contact an electrician to fix them professionally if your Christmas lights still don't work after DIY fixing

testing Christmas lights

Safety guidelines while testing a string of Christmas lights

Most of the people here will learn only about how to test Christmas lights with multimeter. But it is equally important to follow safety guidelines.

First and foremost is that it's important not to use any of the strands for more than 8 hours at a time, or they risk overheating and may catch fire.

If one strand goes out, then don't assume all the others will too--sometimes an outlet just needs to be unplugged.

When testing wires on individual strings with a multimeter, make sure both ends of the wire touch so as not to get zapped by static electricity!

Never test two wires from different strings together because this can create an electrical short circuit which could cause sparks and damage equipment.

Make sure that all your fuses are removed before testing

Do not touch any broken wire without insulation.

Use proper precautions while working with electricity.

If the meter shows any wrong voltages, immediately switch off the power at the main box and contact an electrician.

Conclusion

Fix Christmas lights with a multimeter is very easy as you only need some basic tools and precautions. By following these steps, one can easily repair their broken Christmas lights.

If you still don't know how to test Christmas lights using a multimeter or why it is not working,g then contact an electrician.

Also, read: Best multimeters for electricians

Frequently Asked Questions

Can a broken bulb cause different problems in a string of Christmas lights? Can it make other bulbs go out too?

Yes, It can. But the bulb will always break before other bulbs if there's nothing wrong with the wiring or power source.

What is the maximum number of Christmas lights you can have on a socket?

Generally, Christmas lights don't require a lot of power to run. So, the maximum number of Christmas lights on one plug is 32.

Which are some common causes for broken Christmas lights?

There are some common causes for broken Christmas lights, they are:

  • Exposure to extreme heat. Overloading of sockets with too many connections. Cat chewing on the wires.
  • Cracked sockets due to overheating and overuse of holiday lights.
  • Bad connections between bulbs and sockets, or loose connections in the light string.

Why does my string of Christmas lights not work when one bulb has gone out? Can this kill my whole string of lights?

This is because when a bulb goes out, the rest of them are no longer getting power. So it's really not dangerous at all.


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