How to Repair 3-Prong Electrical Plug

[Jaddie]

Dear Friends

A few days ago the ground of my Master Blaster's plug broke off into my extension cord.

I'm not a card-carrying DIYer, but after wiring up my son's model railroad and doing a Google search for "Repairing 3-Prong Electrical Plug," I found this YouTube video:

Repairing a 3-Pronged Grounded Electrical Cord - YouTube

I read the comments and learned that the instructor made one error: it does matter which wire goes to which blade on the plug. In short, the green wire will go to the ground, the positive or black wire will go to the silver blade (or the blade on the top right of the ground plug if you're facing it), and the white or negative wire will go to the brass blade (or the blade on the top left of the ground plug).

A quick check at Wikipedia provided a wealth of information, including nomenclature and wiring diagrams for this type of plug as well as many others.

Here is the plug I purchased from Lowe's to replace the plug that came with my Master Blaster.

In short, here are the basic steps:

1. Cut off the old plug with wire cutters.
2. Using wire strippers strip about 0.5–0.75" of cover from the blunt end created in the previous step. This will expose three wires, each covered by its own jacket.
3. Strip about half to three quarters of the exposed length of each of the three wires.
4. Twist the ends of each of the three wires so that each is compact and can be threaded through a small opening.
5. Thread housing of replacing plug on electrical cord.
6. Insert each of the wires into its proper place on the replacement plug (green for ground, black for positive or top right, and white for negative or top left).
7. Tighten the corresponding screws to secure the wire.
8. Reassemble the plug and test.

Here are some quick-and-blurry pictures from my iPhone from my Master Blaster repair:

Broken stock plug

Exposed wires after snipping off broken plug. Notice the stringy insulation. I snipped those loose strings off when attaching the wires to their connector points on the replacement plug.

Another image of the exposed wires after snipping off broken plug

Snipped-off plug

Replacement plug properly installed

I'm embarrassed to admit that this process took me half an hour. I forgot to put the replacement plug's housing on the cord prior attaching the three wires, so I had to repeat some of this process.

 

[beamerstrumpet]

LOLOL Been there done that Just a note, the YT guy is correct in that if you do mess up the black and whit, It really wont matter a whole lot. nice to get it 100% but I have done lots over the years and it has never had an ill effect that I could see. Most important though is your Ground.

I also like to splice chords to make them longer. cut, strip, twist ends, match and twist together (after twisting, lay exposed wire flat against insulated part of of wire,,NOW THE IMPORTANT PART: ONCE YOU HAVE THEM ALL JOINED UP, YOU HAVE TO ISOLATE EACH ONE OF THEM. Wrap each connection in electrical tape(or if you have heat shrink,which needs to go on before you twist them together) Once each wire is wrapped, then you can tape them all together. I like to wrap it till its at least 4 passes up and down. Make sure the cord you are adding is rated either same or higher for your tool. This might help ya out at some point also.

 

[Setec Astronomy]

LOLOL Been there done that Just a note, the YT guy is correct in that if you do mess up the black and whit, It really wont matter a whole lot. nice to get it 100% but I have done lots over the years and it has never had an ill effect that I could see.

Maybe nothing you could see, but mixing up the hot and neutral is a big deal and something you don't want to do.

 

[El Flaco Taco]

In short, the green wire will go to the ground, the positive or black wire will go to the silver blade (or the blade on the top right of the ground plug if you're facing it), and the white or negative wire will go to the brass blade (or the blade on the top left of the ground plug)..

Actually it's the other way around. Black wire bronze screw, white wire silver screw. But your machine will still work if the polarity is reversed.

 

[Jaddie]

Dear El Flaco Taco

That's what people are saying.

I was going by the diagram and instructions on Wikipedia.

But now I thinking I'm going to unscrew this thing and wire it your way.

 

[Jaddie]

Dear Friends

All I've been able to find online is that the hot wire usually goes to the brass blade and the neutral wire usually goes to the silver blade.

'Tis true that I have a silver blade and a brass blade. Figuring the manufacturer of the plug must have made it that way for a reason, and on the heels of your corrections, I rewired the plug so the black wire is in the brass blade's connector and the white wire is in the silver blade's connector.

If you guys hadn't corrected me, it would've been wired incorrectly. While some of you maintain it really doesn't matter, it matters to me. This compartment of my life, detailing, is about imposing order on chaos. I'd prefer to be correct whenever possible.

Thank you for helping me get there.

I wrote the tutorial above to help y'all, but, as it turns out, you've helped me.

Thank you.

 

[MarkD51]

Simple way to check, place original Plug in Vice, Hacksaw Plug open, and check.

 

[Detailing by M]

......
I'm embarrassed to admit that this process took me half an hour. I forgot to put the replacement plug's housing on the cord prior attaching the three wires, so I had to repeat some of this process.

LOL! We all have done this so don't be embarrassed. I can't count how many times I've forgot the housing.

 

[Jaddie]

Dear Friends

(The information below has been corrected and updated from its first appearance as the original post of this thread.)

A few days ago the ground of my Master Blaster's plug broke off into my extension cord.

I'm not a card-carrying DIYer, but after wiring up my son's model railroad and doing a Google search for "Repairing 3-Prong Electrical Plug," I found this YouTube video:

Repairing a 3-Pronged Grounded Electrical Cord - YouTube

I read the comments and learned that the instructor made one error: it does matter which wire goes to which blade on the plug. In short, the green wire will go to the ground, the positive or black wire will go to the brass blade, and the white or negative wire will go to the silver blade.

A quick check at Wikipedia provided a wealth of information, including nomenclature and wiring diagrams for this type of plug as well as many others. (I can't link to the Wikipedia article from here. The forum software fouls up the URL, so all I can do is suggest visiting Wikipedia and searching for "NEMA connector." This style of connector is a NEMA 5-15.)

Here is the plug I purchased from Lowe's to replace the plug that came with my Master Blaster.

In short, here are the basic steps:

1. Cut off the old plug with wire cutters.
2. Using wire strippers strip about 0.5–0.75" of cover from the blunt end created in the previous step. This will expose three wires, each covered by its own jacket.
3. Strip about half to three quarters of the exposed length of each of the three wires.
4. Twist the ends of each of the three wires so that each is compact and can be threaded through a small opening.
5. Thread housing of replacing plug on electrical cord.
6. Insert each of the wires into its proper place on the replacement plug (green for ground, black for positive/brass, and white for negative/silver).
7. Tighten the corresponding screws to secure the wire.
8. Reassemble the plug and test.

To the best of my knowledge, the remainder of the original post is correct.

 

[tuscarora dave]

Maybe nothing you could see, but mixing up the hot and neutral is a big deal and something you don't want to do.

That's right. The Safety ground and neutral or common (white wire) work together to provide current a path back to ground in the event of a short circuit. If they're hooked up backward the tool will still run but your path to safety ground is compromised, meaning the tool's user could take the majority of the current instead of it going to ground.

 

[El Flaco Taco]

That's right. The Safety ground and neutral or common (white wire) work together to provide current a path back to ground in the event of a short circuit. If they're hooked up backward the tool will still run but your path to safety ground is compromised, meaning the tool's user could take the majority of the current instead of it going to ground.

I'm sorry but that's just not the case. The only danger to the tool user in a reversed polarity situation like this would b if the user decides to open up the machine and work on it while its plugged in. In normal applications the ground on the device is going to be the best path to ground. Which means no affect on the user.

 

[tuscarora dave]

I'm sorry but that's just not the case. The only danger to the tool user in a reversed polarity situation like this would b if the user decides to open up the machine and work on it while its plugged in. In normal applications the ground on the device is going to be the best path to ground. Which means no affect on the user.

I've been wrong about stuff before...

Thanks for clearing that up.

 

[El Flaco Taco]

I've been wrong about stuff before...

Thanks for clearing that up.

No problem. I'm just happy to be able to give a little back to the forum. Albeit off topic insignificant info. Maybe one day I'll get good enough at detailing to be able to share good detailing info.

 

[Setec Astronomy]

I'm sorry but that's just not the case. The only danger to the tool user in a reversed polarity situation like this would b if the user decides to open up the machine and work on it while its plugged in. In normal applications the ground on the device is going to be the best path to ground. Which means no affect on the user.

Perhaps you could explain to us the purpose of the polarized plugs on most electrical devices?

 

[jfelbab]

It's done for added measure of safety. The neutral side is typically at or very near ground potential and if a two-wire device like a metal toaster or a lamp is not polarized and the hot side of the plug is reversed there may be a greater chance of electrocution. Say touching the lamp bulb socket or the toaster shell and a cold water tap for example. Similarly, the third ground wire is intended to be used to insure the shell of most devices is at ground potential in the case something breaks in the device or the wiring deteriorates. True most two-wire devices with or without polarized pugs are usually triple insulated but the purpose here is to avoid or minimize shock hazards.

 

[El Flaco Taco]

Perhaps you could explain to us the purpose of the polarized plugs on most electrical devices?

Are you referring to the one larger one smaller blades on plugs? I can't. Except to say tht it's internal fusing and switching. Which has no affect on operation.
I'm going to guess that "most" plugs are not polarized. None of the 3 pronged grounded plugs are polarized. And a quick survey of my tools have returned a 50% result of polarized plug ends. My Rupes is not polarized but the 3403 is. My Makita Circular saw is but my Milwaukee Hole Hawg isn't.

 

[jfelbab]

FWIW, The code for wiring in the US:

Protective ground is either a bare or a green wire
Neutral is a white wire
Hot is always black or red in case of a three way.

The plug neutral is always the wide blade and the bronze color connection while the hot connection the narrow blade and is the silver connection.

And all three wire plugs are indeed polarized. They cannot be inserted upside down as the third ground pin prevents it.

 

[El Flaco Taco]

Jfelbab u an electrician?

 

[Setec Astronomy]

Are you referring to the one larger one smaller blades on plugs? I can't. Except to say tht it's internal fusing and switching. Which has no affect on operation.
I'm going to guess that "most" plugs are not polarized. None of the 3 pronged grounded plugs are polarized. And a quick survey of my tools have returned a 50% result of polarized plug ends. My Rupes is not polarized but the 3403 is. My Makita Circular saw is but my Milwaukee Hole Hawg isn't.

So you're giving people safety-related electrical advice, when you don't even understand why it's unsafe, except that you have found the tool still works if the hot and neutral are reversed. The reason that some of the tools you have do not have polarized plugs, is that the construction of that tool does not make it unsafe if the hot and the neutral are reversed. Either that or they were manufactured before the requirement was code or common sense made it that way.

It's fine if you don't understand the intricacies of alternating current wiring systems, but it's imprudent for you to tell people on a public forum that it's ok to circumvent conventions that are there for their safety. As any electrician if it's important to maintain hot/neutral protocol.

 

[720eyes]

It's fine if you don't understand the intricacies of alternating current wiring systems, but it's imprudent for you to tell people on a public forum that it's ok to circumvent conventions that are there for their safety. As any electrician if it's important to maintain hot/neutral protocol.[/QUOTE]


You are correct