Introduction: Kill Bedbugs With Your Christmas Lights

Santa's been checking his list, and every last bedbug is on the naughty list! 
This year, Santa has a present for all bed bugs: HOT DEATH!!

Bedbugs are nationally in the news this year, and I have encountered them in a hotel that I use for business travel. I avoided bringing the bugs home by building my last bedbug killing machine for my luggage (

Why do you need to treat your luggage for bed bugs? Simple. If you happen to be staying in a place that has bedbugs, it's possible for them to hide in the seams of your luggage, which apparently is a favorite place for them to hide after feeding. This can happen in any kind of hotel (in my case, a good-quality business hotel I had stayed in many times before) and it can still happen even if you check the room for bed bugs. I checked, didn't find any, and was still bitten on the first night I was there.

Like my last project, this one uses heat to kill bedbugs. It's similar in operation to commercially available products like the Packtite ( using a heat source in a heat chamber to raise the temperature of items to 125F to kill bed bugs and their eggs.

There was a lot of discussion on my last project - someone called it a "Hacktite" - and people were concerned about the amount of wiring that was necessary and I was thinking about an improved version. Fortunately, inspiration struck while I was hanging my Christmas lights...

Why Christmas lights? I needed a heat source that could put out between 350-400 Watts of evenly distributed heat. Hotplates and hairdryers put out too much heat; and things like room heaters don't have thermostats that go up to 125F. Christmas lights are perfect for the job!

This is a simpler project than my last bedbug killing machine, it requires only the most basic home electrical skills. This version is cheaper, and for this one you don't even need to take a trip down that weird aisle fully of funny-looking connectors at the Home Improvement store for supplies since most "big box" general retailers will have everything you need.

This project necessarily brings electricity in close contact with metal, and uses an electrical appliance (the lights) in a method for which it was not intended. You must follow all the safety precautions in this instructable. Even so, you do this at your own risk, if you have any concerns about building or using this device, please buy a commercial product like the Packtite or hire a professional Pest Control Operator instead.

Step 1: Materials

For this project you will need:
 - A 30 gallon or larger metal trashcan
 - Between 350 and 400 Watts of incandescent Christmas lights:
    - "C9" bulbs are usually 7W each and usually come in strings of 25 bulbs, making 175W per string. Start with one string initially and add a second string if it's cold outside and you need more heat. Two strings (50 bulbs) will give you 350 Watts. 
   - "C7" bulbs are usually 5W each and usually come in strings of 25 bulbs, making 125W per string. Start with two strings initially. Three strings (75 bulbs) will give you 375 Watts and might work a little better if it's colder where you live.
 - A thermometer with a remote probe
 - A thermometer with a long probe (optional, but it will help to make sure you don't destroy your luggage)
 - A christmas light timer (try to get the kind with a built-in GFCI circuit breaker)
   - If your christmas light timer doesn't have a built-in GFCI circuit breaker, then you must either have a GFCI outlet on your house to plug into, or a separate GFCI plug, or an isolation transformer available.
 - A 3-conductor extension cord (one with a ground prong)
 - A 3-prong replacement electrical plug
 - A 3/8" clamp connector for 1/2" knockout (optional, but recommended)

New safety items needed since this Instructable was originally posted:
 - A small sheet metal screw or a ground screw
If you use the wiring method:
 - A short length (about 2 feet) of green stranded (not solid) ground wire
 - Another 3-prong replacement electrical plug or a grounding adapter plug
 - A grounded power splitter (the one I'm using here is a 3-way)
If you use the almost-no-wiring method at step 2:
 - A long length of green stranded (not solid) ground wire, long enough to reach from your bedbug death chamber to the nearest copper water pipe
- A ground clamp (sometimes called a saddle clamp) that allows you to connect a ground wire to a water pipe - there's a picture of it at step 2.

 - Screwdriver
 - Drill (optional, but recommended)
 - Wire cutter
 - Wire strippers
 - If you choose to follow the "no cutting, no wiring' method at step two, you'll need a pipe wrench or similar tool with large jaws.

Step 2: Prepare the Heat Chamber

The heat chamber for this is a 30-gallon metal trash can. The job for this step is to bring an electrical outlet to the inside of the trash can so that we can plug the Christmas lights into it.

My method:
 - Drill a 3/4" hole in the side of the can. I drilled it near the bottom as you can see, but realized later it would actually be a bit more convenient near the top.
 - Install a cable clamp in the hole.
 - Cut the end off of an extension cord near the plug end (not the outlet end). Use a 3-conductor cord. Discard the cut-off plug or store it out of reach of children.
 - Pass the cord through the cable clamp so that the outlet is in the can and the bare end is outside
 - Attach the replacement plug to the bare end of the extension cord, following the manufacturer's instructions, and paying extra-careful attention to the polarity of the wires.
 - Tighten the cable clamp.
It is important to use a cable clamp in the hole. The edges of the hole are sharp, and if the cable is not clamped then the edge of the hole will cut through the insulation on the cord and electrify the can. That would be bad.

New safety instructions since the instructable was originally posted:
Now we're going to ground the can. Even though you must protect your can with a GFCI socket outside (right!), the GFCI is actually supposed to be a secondary protection against electrical failure. The primary method should be grounding. Why? Let's say that an electrical short-circuit forms in the can (from a broken bulb, for example) and causes the live conductor to come into contact with the can. It could sit like that all day, until you touch it and it finds a path to ground through you. The GFCI is supposed to pop and cut the current under these circumstances, but not before at least a little current passes through you. It probably won't kill you. Probably.

Let's go ahead and ground the can as the primary defense mechanism against short circuits. If the can is grounded, then if there is ever a short circuit then the GFCI should pop immediately without any current having to go through you. If the can is grounded, even if your GFCI fails, then it should pop the circuit breaker at your electrical panel.

Wiring method (see the no-wiring method section for the no-wiring method) -
 - Wire up the short length of green ground wire to the ground prong of the extra electrical plug you bought and assemble the electrical plug according to the manufacturers' specifications. Do not wire anything to the live or neutral pins.
 - Drill a small hole in the side of the can to pass the wire out
 - Wind the other end of the ground wire around a ground screw and screw it into the side of the can, as shown in the picture. I did it this way so that the point of the screw was inside the can.
 - Using the power splitter, the lights and your ground adapter must both be connected to the extension cord socket
 - Check for electrical connectivity between the can and the ground prong of the extension cord.

Alternative, no-cutting, almost-no-wiring method:
Get a big pair of pliers, a pipe wrench, or other similar item. I used my "Functional Utility Bar" in the pictures below. Use the tool to bend the rim of the can inwards by about half an inch. It's tougher than it looks. Then when you get to step 5 you're just going to snake the extension cord under the rim of the can.

New safety instructions since the instructable was first posted for the almost-no-wiring method: Strip both ends of the green ground wire that you bought to expose the copper wire inside. Insert one end of the stripped green wire to the electrical connection on the ground clamp and tighten the screw. Find a nearby copper water pipe (probably wherever you attach your hose) and clean a section of the pipe with steel wool or sandpaper until it's a bright shiny copper color and then install the ground clamp on the pipe. Wind the other stripped end of the green ground wire around a ground screw and screw it into the side of the can

Finally, drill a small hole in the side of the can near the top. You'll install the long-probe thermometer through there later.

I chose a metal can because it's low-cost, will not deform with heat, and if a fire were to develop inside the heat chamber then a metal trashcan will contain it and cut off the oxygen. Others have suggested plastic cans would be more electrically safe. Perhaps you could place the metal can inside a plastic can for the best of both worlds. If you are really worried, you should buy a commercial product like the Packtite instead.  

Step 3: Prepare Your Luggage

Do this outside. You are less likely to accidentally release a bedbug into your house, you are less likely to break a bulb, and if the contents of your luggage do happen to catch on fire then you are less likely to burn your house down.

If you bagged your luggage (to prevent the escape of bedbugs while you were getting all this ready), remove the bag now.

Remove anything from your luggage that could be sensitive to heat and treat it separately. This would include medicines and electronics.

Remove anything from your luggage that would be dangerous if heated and treat it separately. This would include aerosol cans, perfume (alcohol), alcohol, lighter fluid, etc.

Remove anything from your luggage that might melt and damage something else in the luggage. This would include anything waxy, lipstick, stick deodorant, etc.

Remove any paper tags from the outside of your luggage.

Place the remote probe thermometer in the center of your luggage. We're trying to heat the coldest part of your luggage to 125F, and the outside will be hotter than the inside.

Take your strings of lights and wrap them around your luggage, trying to space the bulbs as evenly as possible around the sides of your luggage. 

Step 4: Put the Luggage in the Can

Do this outside. You are less likely to accidentally release a bedbug into your house, you are less likely to break a bulb, and if the contents of your luggage do happen to catch on fire then you are less likely to burn your house down.

Make sure the extension cord is unplugged. Plug the lights into the outlet inside the can. Then CAREFULLY lower your bulb-wrapped suitcase into the can, making sure you don't break any bulbs by doing so.

If you followed the alternative method at step 2, then you're going to place your extension cord at the part of the rim you bent earlier, so that you can put the lid on the unit with the cord under the rim.


Step 5: Fire It Up

Do this outdoors. Choose a dry day with no risk of rain. Do this in an area where the device cannot be knocked over or disturbed by pets or children or anyone.

Plug the Christmas light timer into an electrical outlet on your home.  Either the timer or the outlet must have a GFCI protector on it. Test the GFCI protector according to the manufacturer's instructions.

Set the timer to "on". Plug the extension cord from the can into the outlet on the timer.

Set the timer for 2 hours. If it's light outside then you may need to cover the timer with an empty coffee can or what-have-you to "fool" the timer into thinking it's dark out.

Check that you have no broken bulbs or any other unsafe condition in the can.

Install the long-probe thermometer through the hole in the can you drilled earlier. Make sure the end of the probe is not touching the side of the can.

Place the lid on the can. If you followed the alternative method at step two, be sure you've got a medium-tight fit between the rim of the can and the lid, tight enough to hold the cord in place, but not so tight you're going to damage the conductors or insulation in the extension cord.

Step 6: Monitor Often

Monitor the temperature often. You are aiming for 120F on the long-probe thermometer, and 125F on the remote probe thermometer. This is contrary to previous advice I had given when I first wrote the instructable - I realized that the air temperature inside the can is lower than the temperature inside the luggage.

It will take a little while for the can to heat up initially, but you really don't want the temperature inside the can (measured by the long-probe thermometer) over 130F. Remember that environmental factors like wind (or still air) can affect the temperature in the can, so it could hover at one temperature for an hour or more and then change temperature - for me it seems that it can hover for the first hour ot two and then rise 25degrees or so in a few minutes as it gets close to the end of the heating process.

If the long-handled probe goes over 130F, unplug the device, wait for it to cool, remove your bag from the can, and remove a string of lights, and go back to step 3.

If the long-handled probe can't get up over about 100F then the internal contents of your luggage cannot get up to 125F. Unplug the device, remove your bag, and go back to step 3 but add another string of lights.

Experiments with this can show it takes 2 to 2 and a half hours to get the temperature measured by the remote probe in the center of the luggage to 125F

Step 7: 125F and You're Done

When the internal temperature of your luggage reaches 125F, you're done, and whatever bedbugs may have been living in your luggage are now dead.

Unplug the unit, and wait for everything to cool. The waiting period is important here, it makes sure that if there does happen to be a cooler spot in your luggage that the heat can soak in there well too.

Remove your luggage, unwrap the lights carefully, and store the device. Use it after every trip!

I am not a bedbug entymologist, but most of the advice I see on the 'net says temperatures between 115F and 125F are sufficient for killing bedbugs, with less time required at higher temperatures. While this research indicates 7 minutes at 114.8F is sufficient:  , other research indicates 125F is required for instant death of bed bugs. I'm going with 125F.

Other similar devices:
 - The only small-scale, UL-Listed consumer bedbug killing heater that I'm aware of is the Packtite. Like this project, it's intended for small amounts of luggage or other items, and someone else builds the Packtite for you and guarantees its safety. There could be others.
 - The University of Florida has been experimenting with a larger version:

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