Extension Cord Reel




Yesterday I stopped in a Goodwill store and found a 100ft, 14 gauge extension cord... for $15! I looked it up online and the same exact cord sells new for $40-$80 depending on where you look! I love Goodwill :) My wife was a little irritated that I bought it since we already have several cords but none of them are this heavy duty so I couldn't pass it up. Then, last night, I was geeking out on here and I noticed the tools competition, so of course I had to make something I've been wanting to make for several years. I trash picked a wire spool a few years ago and ever since i've wanted to make an extension cord reel with built in electrical sockets like my dad made years ago. Only I had ideas on how I would improve the idea.

His has two sockets in a metal electrical box mounted on top of the reel, with the cord run inside and up to the box. I wanted my sockets to be inside the reel because the box always seemed like it was in the way when winding up the cord. I also wanted a knob for winding it up and a base so I can set it on the ground and just pull the cord to the outlet. I also wanted the base to be a hand hold for winding it back up.

This morning I stopped at my local home improvement store and started searching for parts. It took me a while but I eventually found all the parts I needed. I already had the cord and the spool and I had a wooden knob from a piece of furniture I fixed up. Oh, I also used a scrap of household electrical wire and a wire nut, both of which I already had.

I ended up buying:

(2) tamper resistant duplex outlets

(1) two gang electrical box

(1) metal outlet cover

(1) PVC toilet flange

(1) PVC toilet flange extension ring

(1) 4 inch PVC adapter

totaling $18.30 after tax. I ended up not using the flange extension ring so that takes off close to $4 after tax and puts the total spent right around $30, if you include the cord. I also used a few fasteners I already had on hand.

The tools I used were:

Jig saw

oscillating tool

drill with bits

philips and flathead screwdrivers


sand paper

wire cutters

regular and needle nose pliers

multi meter


A couple helpful comments have been made by some of our knowledgeable cohorts. They pointed out that if the cord is used while coiled around the spool, especially at a high power load, the wire will be subject to an effect known as inductance. Basically, it creates a magnetic field which then affects the conductor and if the current is high enough it can cause the cord to overheat. If you want a more in-depth explanation, there is a link below where you can find a ton of info about. You can also look in the comments to see an photo of a cord on a spool that overheated.

Long story short, if you are using an extension cord it is best to unwind it completely when you use it, especially if you are putting a high load on it (i.e. welder, lathe, electric heater, microwave, (most power tools and appliances really). These examples are not the only things that can draw a high load, check the power ratings on a tool or appliance to be sure. I've also included a page that has common power consumption ratings, it gives a good perspective of how different tools and appliances stack up.



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Step 1: Cutting the Holes

First thing I had to figure out was "how is this crap gona fit?" I used the jigsaw for this part.

It took a bit of finagling with the size of the hole to be able to fit the parts through without making the hole too big. In the end I had to make it bigger than I wanted so I used a scrap piece of hard board as a mounting plate. (I forgot to mention that before. I also had that on hand.) I forgot to take a picture of the mounting plate after it was done. I sanded the edges of it help it look better. In retrospect, I wish I had cut a bigger piece and made the mount plate round to completely cover the metal tabs on the top of the spool. I could have cut a larger hole which would have made things a little easier later on. I also cut a couple tabs off the electrical box.

I also cut a bigger hole on the other side to fit the flange. Be careful with this part, my blade went off track a little and the hole ended up not being as round as I wanted it.

Step 2: Building the Base/Hand Hold

The flange is going to act as a base and also as a hand hold for reeling it in and out. I can't really go much into how I came up with what I did because it mostly looking at it, scratching my head, looking at it more and trying to imagine how it would work. I ended up cutting the adapter piece where the smaller section meets the larger section, leaving the beveled part with the large section. I had to cut the larger ring in half to fit it through the hole on top, thats why I wish I had made the mounting plate bigger and cut a bigger hole.

The way it fits together, the flange goes in through the bottom, the other pieces go in through the top, the smaller ring around the flange and the larger ring around that with the bevel against the bottom of the spool. It's all glued together with caulk. I recommend doing what you can to keep that larger ring in one piece, I'm worried that where the two pieces meet is going to rub on the spool and keep it from rotating smoothly. I might rebuild that part later if it is a problem. It's hard to tell right now because the caulk hasn't set and I don't want to rotate it until it is.

The way I assembled it, I put a bead of caulk around the inside of the beveled sections, put those in place, put another bead in the top of the gap between the flange and those two pieces and then slid the smaller ring in-between and pressed it all together.

Step 3: Wiring

Next up is the wiring. I had to pause a second when it came time to cut the female plug off the cord. Once I cut it off there would be no turning back, but i figure out of the cords I have, its the best one to use for this so off it went. I cut about a foot of the cord off with the plug so I can use that for something else later on. I don't know for what, but I'm sure it will come in handy at some point.

Electricity is dangerous so if you are not familiar with how to wire an outlet, make sure you study up on that so you don't wire it wrong. The black wire is hot and goes to the brass screw and the white wire and goes to the non-brass screw. The other (it was green in my cord) goes to ground. Here is a link to an Instructable with a video if you need a visual aid https://www.instructables.com/id/How-to-install-an...

I cut off the plug, stripped the wires and ran it through a hole that just happened to be the perfect size and spot. I can't guarantee that your spool will be as cooperative so do what you gotta do. I drilled two small holes in the bottom of the electrical box and used a zip tie to secure the cable. Next up, I used the scrap of household wiring to connect the two plug sets together, then I attached the cord to the other set of connections on one of the socket sets. There was only one ground connection per set so I left a tail coming off one of them and used a wire nut to attach the ground wires. It's kinda hard to see in the picture, sorry that didn't get a better one.

I tested it with the multi meter to make sure everything was wired correctly.

The outlets I got are described as "tamper resistant". If you look in the outlet in the last picture, there are plastic pieces blocking the openings. They move out of the way when you plug something into it. The display where I found them said that it's supposed to be safe for kids but I think it will be great for keeping saw dust and other debris from getting into the outlets.

Step 4: Final Assembly

Now to wrap it all up. The outlets, box, and cover plate were attached to the mount plate which was then attached to the spool. Then I attached the knob and wrapped the cord around the spool.

Hope you like this, if you do, I'd love some votes! Thanks

After Thought -

In all honesty, the base/hand hold will probably bother me and most likely I'll end up taking this thing apart and rebuilding that and putting a bigger hole on top with a new mounting plate. If I do, I'll probably shorten how far the hand hold goes inside so it's easier to wrap my fingers around in there. Right now it's too close to the electrical box to get a good grip in there so I recommend cutting maybe a half inch off the shaft of the flange and cutting the other two pieces to the same height.

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    41 Discussions

    With all the comments i'm surprised no one picked up on the bare jacket of the cord going thru the sheet metal tube with no rubber grommet or heat shrink tubing on it for wear protection. The maker is going to be rolling and unrolling this cord and will wear a hole in the covering eventually causing a short.

    1 reply

    Good catch. I’m actually a little ashamed I didn’t think of that myself. I work in aviation and I’m normally good about spotting a chaffing issue. I’m not worried about it myself right now. I don’t use it that often and even more rarely unwind it all the way. I’ll be sure to keep an eye on it though and if I take it apart at all I’ll be sure to fix that


    3 years ago

    You could cut an extra board, roughly the same diameter as the spool, with a handhold that sticks out beyond the spool. Then mount the spool to it with a 'lazy-susan' bearing.

    http://www.amazon.com/Susan-Bearings-Thick-200-lb-Capacity/dp/B0006LBVDI (See also: Lowes, Home Depot, etc.)

    1 reply

    3 years ago

    The inductance is trivial and regardless is not responsible for any cord heating. However a coiled cord subject to heavy loads/current will get hotter than one that is not coiled. Standard wire tables usually include the current ratings of bundled versus free air wires. Just google it.


    3 years ago

    I appreciate the info about inductance - I was trained a lifetime ago as a flightline electrician on military aircraft, and my dad was a commercial and residential electrician, and it still didn't occur to me that this could happen. I've been anxious to find a reel that doesn't cost an arm and a leg but now wonder if I ought to just leave it alone...


    3 years ago on Introduction

    if you need more information about <a href="http://911electronic.com/tunnel-diode-characteristic-symbol-definition/">tunnel diode</a>, you can click in this link. I check this site and there are some information about tunnel diode.

    I think your project is a good idea but it looks like the cord you used does not have a ground prong. This could be a lethal mistake.

    1 reply

    4 years ago

    Inductance is a non-issue. The current in the hot and neutral wires is balanced, so the coil has an exactly equal number of clockwise and counter clockwise turns.

    There IS a problem with using a coiled cord: Heat can build up due to
    lack of air cooling. The heat is proportional to the square of the current, so a 10A load heats the cord 4x as much as a 5A load. Once the cord begins heating, the resistance increases, which causes even more heating. When the cord gets hot enough to damage the insulation, the conductors can short, causing a catastrophic failure. Even if this does not happen, a hot cord can drop enough voltage to cause performance problems.

    2 replies

    Reply 4 years ago

    Ok, that makes sense. So the magnetic fields created by the two conductors would counteract each other?


    Reply 4 years ago on Introduction

    Pretty much. There will be a strong field _between_ the two conductors, but not around the pair. If you have ever used a clamp type ampmeter, you will get no reading if you place it around an extension cord. To get a reading, you have to place it around a single conductor.


    4 years ago on Introduction

    That's pretty awesome, but mount it on bicycle wheels and it would be legendary! Ooh, I have some crappy snowblower pneumatics that would be perfect.


    Very nice instructable. Having built a few of these myself, I appreciate
    your method. I believe I will use your method next time I build a cord
    reel. I would note: if you pay $120 for a 14ga. 100 ft. cord, you are
    paying waaaaay too much. Try $39.97 at Home Depot. It's only $84.97 for a
    12ga. cord. So you actually got the cord for a little under half price.
    Then the biggest problem with a 100ft. 14ga. extension cord is that it
    will only support a moderate (around 5-6A.) without a substantial drop
    in voltage. I use a 100ft. 12ga. extension cord for my 18" electric
    chainsaw which draws 14A @ 120V. A few weeks ago, I cut the cord so I
    had to resort to a 14ga. one. There was a distinct difference in the
    speed of the motor with the smaller cord and the smaller cord will get
    warm. BTW the wider terminal (usually marked with a silver colored screw) on the outlets gets the white wire.

    1 reply


    I see what you mean about the price. Even know when I look on Amazon I don't see it listed for $120. There is a listing for around $80. Maybe the seller was trying to gouge the price or maybe that price was for two of them. Who knows.

    This is the thickest gauge cord I've owned so far. The other two main cords that I own are a Rigid(probably 16ga.) and a super cheap cord thats probably even smaller. I've never ran anything off of them that draws that much power. If I'm doing the right math your chainsaw is pulling about 1,600W. I mainly used them for a 1/4 in drill, small miter saw, and a cheap airless spray gun so i'm not sure I've put enough of a demand on them to make a difference. I'll be sure to remember that for the future though. Thanks


    4 years ago on Introduction

    Thanks for the comments!

    I'm trying to think of how it can be modified so the outlets are stationary. I have an idea but thats going to require a bit of tinkering to figure out though.

    2 replies

    Reply 4 years ago on Introduction

    You are going to need a slipring assembly. Making one of those, especially for line power, is not a trivial task, involving laborious lathe work with brass, sliding contacts, and insulating material that encloses the entire thing. Been There Done That (almost)! I made a 96 channel slipring for work, but it didn't carry hazardous voltages. It took me a week, and that was after I designed it.


    Reply 4 years ago on Introduction

    Thanks for sharing your experience. I figured it wouldn't be a simple task and based off your input probably beyond the scope of the tools I have without creating something potentially dangerous.