HOW TO EASILY FIND BAD CHRISTMAS LIGHT BULBS using a non contact voltage tester

The method used in this video requires a Non-contact voltage tester (affiliate link):

Time index
0:22 How the lights are wired and why some can be off with others lit
0:59 How a non contact voltage tester can help find blown bulbs
1:58 Demo using the voltage tester to find the bad bulb
5:30 Use a binary search to find the bulb faster without testing every one

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[TheAMVDJ]

The immense feeling you get after plugging in a lightbulb and the whole strand finally lights up is indescribable

[brakubee]

Dude it's people like you who take time to share some good knowledge that many of us love you tube. Thank you for this. Made perfect sense. Worked like a charm.

[johncoops]

When troubleshooting series strings (or anything wired in a similar way), always start in the CENTRE. That tells you which half of the string is dead. Then test at half way within the dead half section... in that way you can isolate which (quarter) section contains the fault. Then drill down further in the same way.
So in this case of 50 lamps you'd first test to determine which is the active (line) end of the string, then test bulb number 25. If that bulb has power, then test Bulb 37, if that works, test Bulb 43, etc.
EDIT: That's the method used in the follow up video (linked in description).

[scottfurlong]

I'm an electrician who makes a living at diagnosing electrical issues in old and newer homes. It's very rewarding work and I enjoy it a lot. I'm proud in saying that in 11 years we've yet to walk away from something we couldn't find and fix. I have 7 or 8 pieces of electrical diagnostic equipment and experience. I still absolutely despise those chain type Christmas lights.

[timsawyer]

What a lifesaver! I'm in charge of the "official" Christmas tree for our county, and every year we end up buying new strings because of a bad bulb (or two, or...), since nobody has the time or inclination to go through bulb-by-bulb and find the problem child. This will save our Chamber if Commerce (all volunteer, self-funded) a good bit of money over the long haul. Thanks!

[toonchi]

When I started this video I had 1 burned bulb, after the video finished I have 20 smashed bulbs because I stomped it out .

[meangreen]

Sometimes it takes a lot of words to explain something simple but you’re articulate and pulled it off, thanks for sharing this technique.

[barrybegley]

Even as a retired electronic technician, I don't think that I would have thought of this approach. It's quite ingenious actually. Just shows that we can always learn something New. Thank You for the clever incite. Barry Howard Begley

[squirrelydan]

I still can't find the burnt out ones even after this method. There's a special place in hell for the designer of Christmas lights.

[jjwkds]

If only Clark Griswald would have known of this sorcery. Great idea. Thanks

[rominhawk]

Actually, this is a very good presentation of how to find a bad bulb. I followed your instructions and flipped the plug to switch the hot wire; and was able to find the bad bulb. But, it was a bit of a learning curve for me; but, once I got it, I figured what to look for; because the tester was sometimes not chirping for a particular bulb, and I'd go back to the previous one and it chirps; I come back to the bulb that wasn't chirping only to find that now it's chirping. And for one of the sockets, I had to use the shunt fixer to fix a bad shunt. I had to change 10 bulbs.

Thank you very much for a great presentation.

[robertlalum]

I was an engineering technician for an r&d company this is ingenious I would have never thought about this

[WatertownFilms]

Every year I pull this same video up to figure out how to fix my lights again.

Thank tou

[fishontv]

Bro. I was playing around with a ohm meter for like 2 hours trying to find the break. No idea why my brain didn't think 'Use the non-contact voltage tester'. I'm so used to working in DC with LEDs, my brain didn't click. Thank you. After watching this video for like 2 minutes, I went downstairs into the shop and found the break in like a few minutes. It wasn't a light, but a contact inside the housing that was pushed down and wasn't making contact. The lights have shunts in them so I knew it probably wasn't a broken shunt AND light. I love YouTube :)

My kingdom for parallel LED light strands. Serial LED light strands are as evil as printers.

[alicearmstrong]

Just knowing that a voltage tester can help find the burnt out bulb without pulling out the bulb was a time saver. I strung my lights before testing them and didn't have to pull them down to find the one pesky burnt bulb.
Thanks for the tip!

[jasonsmith]

I use one of these tools at work. I'm so used to agonizing over pulling bulbs that I never thought of THIS!

Forest for the trees moment.
Thanks for this!

[dwp]

Thank you! I did consider myself somewhat knowledgeable at one point in my life but as I get older I realize how little I know about everything. Merry Christmas!

[BradBo]

I’ve been trying to fix these for years. I even bought the kit to check bulbs. Now I understand flipping the plug and how the circuit can fool you if you flip the bulb and how to shield. Now I won’t be running these to the recycle by the dozen! Thanks so much.
By the way, my wife is crazy for lights. We even have 6’ icicle lights coming down around the house from the gutter. I’ve had to pull 2/14 from a source with plug receptacles every three strings to handle the series load and mount them under my overhang.You cant miss our house!!!!

[eugenepolan]

A good place to apply the Fibonacci search technique! Check both ends, then check a place offset from the middle - you have the potential of zeroing-in on the bad bulb in fewer moves.

[garrettmccleary]

This dude deserves a medal! Bravo my man thank you for saving me so much time and frustration