I am setting up christmas lights. I have two shrubs which are about 6 feet apart, and I want to put an LED string set on each. I bought a two-prong outdoor extension cord to run between the shrubs.

The prongs from the extension cord do not fit into the end of the LED string. However the LED prongs can plug into the other side of the extension cord without issue.

Do you need some sort of converter to allow the prongs of the extension cord to go into the xmas light string set?


This is the extension cord prong end: enter image description here

This is the LED string light end: enter image description here

The packaging of the extension cord says it is polarized.

  • Can you post photos of the socket on the end of the light string and the plug on the extension cord? Dec 20, 2017 at 2:51
  • 1
    See polarized vs non-polarized plugs.
    – Dan D.
    Dec 20, 2017 at 3:18
  • @ThreePhaseEel added a photo.
    – user79295
    Dec 20, 2017 at 12:10

3 Answers 3


Thanks for the pictures! It looks like the problem is that your extension cord is polarized, but your Christmas lights aren't. The best solution is to replace the electrical receptacle at the end of the first set of lights with a polarized one. They sell replacement receptacles for Christmas lights.

replacement receptacles for Christmas lights

You could use a ground plug adapter to do this, but you would need to trim the polarized neutral plug to fit in a non-polarized hole which is a bad idea. It will be fine for this season, but once you take your lights down for the season you'll forget that you have a modified adapter that could be reused for something else and hurt somebody.

ground plug adapter

  • More likely the light strings are non-polarized (both prongs same size) while his two-prong extension cord is polarized so the larger neutral prong won’t fit.
    – DoxyLover
    Dec 20, 2017 at 9:45
  • Yeah the extension cord packaging says it is "polarized".
    – user79295
    Dec 20, 2017 at 12:09
  • 4
    This is the obvious solution, but it creates the risk that the extension cord will provide reversed polarity current to devices which are sensitive to it. Use with caution.
    – isherwood
    Dec 20, 2017 at 15:18
  • 5
    I always assumed this was intended to prevent the casual user from using christmas lights as extension cords, since their wiring is so light duty. It's really not a good idea to attempt this unless you're confident that the draw on the system is low enough!
    – aaron
    Dec 20, 2017 at 18:18
  • 1
    DIY hacks with electrical plugs are dangerous. Don't do this - it doesn't fit for a reason, and that's because it would be dangerous. Don't stubbornly cheat what has been carefully idiot proofed for you. This is how you win Darwin awards.
    – J...
    Dec 14, 2020 at 11:44

Can you plug the extension cord in near the first bush, using a splitter or three-way tap if needed, and run it from there to the second bush? That would avoid the need to modify anything.


Do you have an old string of Christmas lights you can sacrifice? If so, you can convert it into a non-polarized extension cord. The basic technique is shown in this video. If you search online, you'll easily find other sources for the same information.

One problem I have with the video is that he splices the wires by twisting them together and wrapping them with electrical tape. That can work, but I'm not happy with it from a safety standpoint. I recommend using solder and heat shrink tubing. For outdoor use, get the type of heat shrink tubing with adhesive in it to keep the water out.

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