Tripped fuses and Busted Bulbs of Xmas Lights – How I Fixed Them

Yesterday, I was prompted by my wife to hang the Christmas lights outside the house. It’s one of those rituals that are dreaded by most husbands of the households but the wives/kids couldn’t get enough of it, as if the redistribution of wealth from the breadwinners the rest of the families wasn’t enough. I know, I sounded like a scrooge. Happy holidays!

This was my second year hanging the same lights on my residence. I should have drawn a wiring diagram for next year as it’s hard to remember what we did last year. It’s supposed to get easier but it didn’t.

Fuse Problem:
After hanging up the Xmas lights, I noticed one of the two light branches kept burning the 3A fuse. I didn’t have a problem last year. Suspecting a bad Xmas light link within the chained 7 links, I brought out my Kill-A-Watt and measured it was registering 3.5W! So I turned it off right away to avoid burning the 3A fuse again. Now I need to isolate the “bad” link. I figured I should just characterize one link at a time to determine the current requirement. Sure enough, each link uses 0.5A (or 60W (0.2W per bulb)) and 7 links makes 3.5A. There was nothing wrong with the links but the way I chained them to the outlet. After re-distributing the current load to another chain, I no longer have the burned fuse problem. Each chain would handle 2.5A. One down!

Bulb Problems:
Next, I noticed one particular segment of the link no long have lights. Sigh! Diagnosing down to the light bulb out of 50 in a chain was going to be a nightmare. I googled around and familiarized myself with how the Xmas lights are wired together and how the circuit works, thanks to this website. I also checked Youtube videos and found there is this Light Keeper Pro tool that’s supposed to be a panacea for all the Xmas lights woes. I went to the local hardware store and bought one for $20. Also bought some spare light bulbs just in case.

light keeper pro

light keeper pro2

Well, I was able to fix one of the Xmas light link with this device. By pulsing/zapping from the bulb socket, this device worked to short/bridge the bad weakest-link bulb (each bulb has a “shunt” or electrical bridge to engage when the bulb turned bad), allowing the rest of the stringed bulbs to work. Then I replaced the bulb and all was well. Another down!

On another link, Light Keeper Pro’s zapping/pulsing didn’t work. I used the hum/tracing function and found 3 bad bulbs! The zapping function wouldn’t work if there are more than 1 bad bulb – it didn’t have enough energy to zap more than 1 bulb. But the humming function worked well. One more down!

On my final link or a mesh/net, neither the zapping nor the humming worked. The humming allows me to trace to a smaller branch but it couldn’t isolate down to a particular bulb. I need more time to debug this case next couple of days. 3 downs, 1 to go!

Overall, it’s a good Xmas light hanging experience. I didn’t realize I had such a great opportunity to learn about something interesting and refresh my circuit background.