I’ve done such repairs using insulated straight electrical crimp connectors. They provide a much better connection than my soldering (non-)skills. They may end up being a bit more bulky, but that may not matter – this patch is going to be bulkier than the original cable in any case.
There’s no homeowners OSHA, of course, but in industrial and construction settings, any sort of repairs must be done by a liscenced electrician. Probably for a good reason.
It is easy to make a strain-proof repair in a few minutes with nothing but a utility knife, electrical tape and three properly sized wire nuts.
Do not replace the plug. It will never be as waterproof or secure as the original and will be annoyingly bulkier.
When I repair a cut expensive extension cord, I leave alone the native molded plugs, use wire nuts and electrical tape, and provide strain relief by binding together the two cords approaching the repair so that the linear stress is on the tape binding the two cords together and not on the wire nuts. I wrap each wire nut repair individually and then collectively, exposing only as much outer casing as necessary to free the wires. Then I extend the whole wrap down over the incoming cords so that the strain is not on the wire nut. When the cord is strained, the electrical tape binding the two ends together will easily take the strain. Learn how to stretch electrical tape as you apply it, and pull it until it snaps at the end of a bind. Don’t cut it.
When you use the wire nut, which has an internal metal cone with threads in it, simply expose just enough bare wire to extend fully into the nut, place both bare wires together, and screw on the nut until tight. Use nuts without tabs, because they will be easier to wrap with electrical tape, and expose each insulted wire enough to get a wrap onto the two incoming ends.
This is strong, simple, waterfast and effective. It leaves about 4-6 inches of a bulky ball of electrical tape.
Most of the solutions above strike me as ridiculous overkill for a $30 extension cord. It’s just silly to solder wires together, for example. Very few of the electrical connections in your house are soldered. It’s just as ridiculous to use shrink wrap when electrical tape is effectively the same thing.
Except that it’s not. I love the attitude that tools and techniques can’t cross functional boundaries, and that only solutions found in the right store aisle can be used in any particular situation. In particular, I’ve lost count of those who howl at the notion of soldering car or electrical connections - by god and GM, only screw and crimp connectors can be used on cars, and only wirenuts and screw terminals in AC wiring. No matter what. That’s the Lawwwwww.
Soldering and shrink-wrapping a repair may be a “foreign” solution to a union electrician, but it produces a strong, permanent repair whose only downside is that a foot or so of the repaired cord is less flexible. I’ve had such repairs outlast the rest of the cord.
All of these standard house-wiring approaches, with twisted connections, wirenuts and gobs of electrical tape, seem impossibly half-assed to me - WHY have a bulky knot in the cord that’s going to catch on everything, tape that’s going to slowly unwind and a connection that can be pulled apart with moderate strain? I’ll take all the downside of a replacement connector over that, and I hate the things.
Solder and shrink wrap are just as valid in car and AC wiring as they are in your basic Heathkit. Just because it’s not in the standard toolkit for the field doesn’t mean it’s a bad idea. Or heresy. Or girly-man. Or whatever the objection is.
One piece of advice I picked up early on was:
“Solder all solderless connectors.”
Crimp connectors (or wire nuts, for that matter), are purely for assembly convenience, not for longevity or reliability. I insist that our assembly guy solder all the crimp connectors for the Molex plugs on our product.
And anyone who thinks all that effort isn’t worth a “$30 extension cord” hasn’t priced the damn things lately. Whether it’s the copper, the manufacture or just plain gouging, decent-gauge, decent-quality cords have gotten expensive.
Chief P’s got it right about trying to keep the original molded connectors, though. Almost any option is better than tossing a good molded-on connector in favor of a screw-terminal repair one.
when using electrical tape don’t pull and stretch to break and finish the end.
slightly stretched tape is good in the middle of the repair, it holds and is sealed tighter then.
the end of any wrapping should have a few wraps of untensioned pressed down hard. the untensioned tape has stronger adhesion.
All good advice here, but ultimately you have to ask yourself the age-old question: how good is good enough? If your standard is perfection, then toss the cut cord and buy a new one. If your standard is to just get the thing working again so you can get on with your life, then go with something like Chief Pedant’s approach. I’ve got one 20 year old cable that has been cut and repaired so many times that almost every solution mentioned above is represented. They all work reasonably well.
In post 13, amateur barbarian gives good instructions. I do have a slight issue with step 8’s “use plenty of solder” statement. It is not exactly wrong, but I have seldom seen a joint made by an inexperienced person that did not have excessive solder, and often this was an indirect cause of failure.
The ideal amount of solder will fully wet the conductors and form a just perceptible fillet between them. The outline of individual strands will still be visible, and there will be no lumps of solder hanging off the joint.
Excessive solder soaks the wire for a longer distance and increases the odds of breakage due to stress concentration. It also prolongs the cooling time leading to a greater chance of:
The most common failure of such joints is due to movement while the solder is cooling. Some sort of mechanical fixturing like temporarily taping a stick to the wires like splinting a fracture will avoid this. A second pair of hands will serve but gloves or rags may be needed as it is hard to hold still when your fingers are burning.
There are a lot of things in my long post that take some additional judgment - the length of the shrink tubing, how far to keep the tubing from soldering heat, exactly which kind of join to use on the wires. I wrote them mostly for the inexperienced user, and while I pride myself on my deft soldering skills (I put the final polish on with SMCs) I know how most people do it. By “plenty of solder” I meant mostly to avoid one glob, half-melted onto both conductors. Filling the joint well is better, even with the general concerns you mention.
A well-soldered joint should be smooth, shiny, and show the outlines of the wires that are soldered together. No blobs, no points and (ideally) no solder anywhere near a component case or wire sheath. But this is pretty heavy-duty, DIY repair work and strong and sturdy is more important than neat and ISO-quality. 
Well, if you want to be really overkill, go the surplus store and get military grade Canon Plugs, and potting compound, good soldering supplies and then spend the time.
Bawahahaha
IMO, 15 amp 100’ cord is an accident waiting to happen and a tool killer.
30 amp or more is a good extension cord for working tools or things with motors. IMO
What I do when the tide is rising with no way to get to the mainland and what I do back at the shop during down time is usually two different things.
If you have time to ask on a message board, you have time to do it the best you can with your personal skill abilities.
What is your time worth? How much $$$ you got, etc…
A good solder job with good shrink wrapping, all the way up to & including the outer case. Just under the outer case where it is cut away there is 2-3 length ways fiberglass tape wrapped with fiberglass tape & black tape so that the last outer shrink wrap will come out almost normal in the middle.
You have tension strength and a lack of real flexibility of 6-10 inches would not be bad. IMO.
I’m probably not adding much here, but I’ll still give my two cents.
My first thought is to install a high quality, inline receptacle w/ integral strain relief. Hubbell and NewLine make good stuff. But for the price of one of their receptacles, you may as well buy a new extension cord.
As stated by others, the only approach that makes economic sense is to chop up another extension cable and make a splice.
If I were doing it, I would use eutectic, rosin-core solder and heat shrink tubing. Amateur Barbarian has a good procedure, but I do things a bit differently:
- Cut & strip wires. Stagger the joints.
- Insert heat shrink tubing over each of the three wires.
- Insert a long piece of heat shrink tubing over the whole cable.
- For each of the three wires, simply shove the strands together so that they intertwine. (Think of your fingers when you hold your hands… the fingers on your left hand are intertwined with the fingers on your right hand when you shove your hands together.) Doing this will make the joints very strong.
- Solder each of the three splices.
- Use a Dremel tool and cylindrical grinding bit to smooth each solder joint.
- Slip heat shrink tubing over each solder joint and shrink it using a heat gun.
- Slip heat shrink tubing over all the solder joints and shrink it using a heat gun.
Yes there are heavy duty female plugs which are held on by the screw as well as a plastic part which grips the cord as it enters the body of the plug. I have used dozens of them over the years.
This is the right answer. In Canada, we have the same sort of compression fitting. Soldering, crimps and electrical tape will hold and I would consider that if you had cut the cord in the middle, but you are only losing 2 feet. Do it right, do it safely, put a new end on.
Not after reading post 11.
Replacement plugs are quick, convenient, expensive (often half the cost of a new cord or more - and the cheap ones aren’t worth buying) and limit the cord’s uses.
Inline repair takes some time and materials, a little expertise, but is nearly costless and returns the cord to original condition.
Choose wisely.
Yeah, the “getting sued” reason. The descriptor “good” is bent in this scenario, of course.
it’s true that many outdoor yard tools will only take a molded receptacle.
a good inline repair (which i only would do to preserve a molded end for that reason or if i would loose 10 feet or more of cord) does take lots of time.
a splice needs 6 to 10 inches. heat shrink tubing to fit the wires and the jacket, the highest quality electrical tape, a soldering gun. the splices should be staggered and twisted mechanically tight, soldered smooth to no larger than the wire and insulation diameter. each splice covered in heat shrink tubing. the whole splace area wrapped in tap to bring it to the cord jacket diameter for its whole length. the whole area plus a few inches covered in heat shrink tubing.
the repaired area will be much stiffer, which may be a problem if near you.
use orange jacketed cord so you can see it. always be holding, placing, throwing the cord in back of you.
Interesting read. In this part of the world we use 240V and it is to my understanding not within code to use solder for this kind of repair. Solder certainly is not used for any kind of fittings.
I can buy a 25 metre extension cord for $20 (AUD) or pay a few dollars more and get one rated to 15amps. I can also buy a replacement plug or socket to fit onto the appropriate end for about $6-$8.
So, standard procedure would be to buy a replacement plug and wire it on, throwing away the short bit. If it was cut near the middle you would probably consider buying two plugs and ending up with a couple of shorter cords. (My dog chewed the middle out of one not too long ago.) Then again, at a mere $20 I have often just bought a replacement and thrown the damaged cord into my special box in the shed which I raid whenever I need a cord of a particular length.
I would never dream of doing a soldering job such as AB has described.
It’s the first thing I would think of, simply because I have the tools to do it. I already have the soldering iron and solder. And wiring stripping tools. If anything, I may need to purchase some HST, which is very cheap.