Replacing 3-Prong Electrical Plug

Jaddie

Jaddie

New member
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:

master_blaster_plug.jpg


Broken stock plug

master_blaster_plug_1.jpg


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.

master_blaster_plug_2.jpg


Another image of the exposed wires after snipping off broken plug

master_blaster_plug_3.jpg


Snipped-off plug

master_blaster_plug_4.jpg


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.
 
Congratulations on replacing the plug head of your master blaster.

I found it interesting that the black hot wire went to the silver post and the white neutral wire went to the brass post, because when you wire a electrical outlet, the black hot wire goes to the brass screw side of the outlet and the white neutral wire goes to the silver screw side of the outlet.

In any event, since the electricity most commonly used is alternating current, it really wont matter which wire is on which post, except of course the green ground wire which should always go to the correct post.

Glad you were able to do this successfully !

Dan F
 
Stokdgs said:
Congratulations on replacing the plug head of your master blaster.

I found it interesting that the black hot wire went to the silver post and the white neutral wire went to the brass post, because when you wire a electrical outlet, the black hot wire goes to the brass screw side of the outlet and the white neutral wire goes to the silver screw side of the outlet.
Click to expand...

I found that interesting too, I've never seen that. Typically the neutral goes to the silver. I would probably correct that. Also, not trying to criticize, but next time I would recommend soldering the strands of copper.
 
Dear Friends

My felt sick at my stomach when I read your more experienced observations, but I double-checked Wikipedia and my plug, and I believe I have it correct. (Go to Wikipedia and search for "NEMA connector." The forum software obfuscates "wiki" with "####" in the link.)

Do you think I should have wired this particular plug the other way? Maybe this plug has its hot and neutral blades reversed. Silver is definitely to the upper-right of the ground plug, brass to the upper-left.

Thanks for keeping me honest.
 
Jaddie,
It will be fine. Alternating Current (A/C) does exactly that. Goes up one and down the other.
There are zillions of outlets and plugs wired either way and no one has burned their house down yet.. :)

If anything was wired incorrectly or badly, it would have sparked/and/or thrown the circuit breaker immediately.

Dan F
 
Dear Dan

The Blaster ran fine. The plug was a little warm, but I figure that's just from the heavy draw.

I want to be correct.
 
It will be fine. Alternating Current (A/C) does exactly that. Goes up one and down the other.
Click to expand...
Unless it's polarized. Then it must be hot-neutral-ground.

The original plug does not appear to be polarized.
 
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.
 
Dear Friends

On the original plug there are a W by one blade, a G by the ground plug, and a diagram indicating continuity between ground and W and discontinuity between ground an the unlabeled blade.

What does W denote in this context?

master_blaster_plug_6.jpg
 
I just put a continuity tester on my Metro Plug which is labeled just like yours.

Doh!Scratch that first one. I can't remember the results from garage to house.

There is no continuity between any prong on the plug, but there is ground continuity between G and the housing.

I called my electrician. According to Troy, the W designates "outdoor use".
 
Mr. Gloss said:
I just put a continuity tester on my Metro Plug which is labeled just like yours.

Doh!Scratch that first one. I can't remember the results from garage to house.

There is no continuity between any prong on the plug, but there is ground continuity between G and the housing.
Click to expand...

Dear Mr Gloss

Does this mean only the ground plug matters?
 
Dear Mr Gloss

I just called my electrician, too, aka my paw-in-law. He says W denotes white. I'm unable to corroborate this with online sources, but I bet someone with more knowledge can find it.

I'm still searching for an authoritative source and found a guy who assumes G denotes green.

So far I'm inclined to believe W is for white and G is for green. I'm inferring this information from this PDF.

My paw-in-law is giving me a hard time about paying a "ridiculous" price for my plug. He cites this plug that he bought on sale at Harbor Freight for US$0.59. It's now US$2.99. I paid US$4.34 for mine. The Harbor Freight plug has identical blades, unlike mine.
 
I was also thinking W" denotes white or Neutral, since there are only 3-colors if you are lucky and they are all different.

You are still fine...

My Master Blaster with both motors on, will heat up the cord a little, after a long while of Blasting.

Hotter weather will increase the amount of heat because it cannot be cooled as fast when the ambient temps are higher...

If you see nothing wrong, hear nothing wrong, and especially do NOT Smell anything like plastic/rubber burning, you are good to go..

Usually the ground brass prong on the plug falls off, breaks off, and then I dont have one there.

Since I dont mix standing water with electrical devices, I will always be ok with this until I decide I may want to fix it - or not -

Dan F
 
It is always good to check your outlets with an electrical tester to see if they are all wired correctly.
 
I was also thinking W" denotes white or Neutral,
Click to expand...
If it does indicate white, then if you have the white lead connected there it is correct, since when you plug it in the W prong will insert in the longer slot, which should be neutral or white.


"W" is stamped on every outdoor approved power cord.

It is always good to check your outlets with an electrical tester to see if they are all wired correctly.
Click to expand...

Especially when operating switched devices.

Usually the ground brass prong on the plug falls off, breaks off, and then I dont have one there.

Since I dont mix standing water with electrical devices, I will always be ok with this until I decide I may want to fix it - or not -
Click to expand...

It has nothing to do with water, it's to keep you from dying from a fatal shock.

The idea behind grounding is to protect the people who use metal-encased appliances from electric shock. The casing is connected directly to the ground prong.

Let's say that a wire comes loose inside an ungrounded metal case, and the loose wire touches the metal case. If the loose wire is hot, then the metal case is now hot, and anyone who touches it will get a potentially fatal shock. With the case grounded, the electricity from the hot wire flows straight to ground, and this trips the breaker in the breaker box. Now the appliance won't work, but it won't kill you either.
 
Ok, last thing I will ever say about this -

"It has nothing to do with water, it's to keep you from dying from a fatal shock."

If everything else is working, and the chances of a wire flying off a connector is hardly EVER going to happen, then probably, the ONLY thing that can happen in Detailing for the majority of people, is water on the floor, and an electrical cord connected to an extension cord that is dragged onto or over a wet surface.
So, to me, it has everything to do about water and its ability to conduct electricty..

Im done here, too many experts... :)
Dan F
 
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