Replacing 2 prong outlets

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Nick1994

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While over replaced quite a few outlets and light switches before, I haven't upgraded them from 2 prong to 3 prong.

This is for my grandparent's house. It's a red brick house built in 1949-1950 and the 3 bedrooms still have 2 prong outlets and the rest of the house has been updated to 3 prong outlets at some point. I have opened up one of the outlets and pulled it out a bit and the back of the gang box has a screw hole for a ground wire.

Can I just run a ground wire from a new 3 prong outlet and screw it into the back of the metal gang box?
 
I don't think connecting ground wire to the metal gang box would do any ground fault protection.
I had a house built in 1952 and I had electrician update all 2 prong to 3 prongs for me. He had to put at least one GFCI in a circuit. i.e. if you have 6 outlets on one circuit you can replace 5 with regular 3 prong outlets but the 6th one has to be GFCI. Also, all outlets must be marked with"GFCI" stickers. At least in State of Washington.
 
Originally Posted By: 5AcresAndAFool
What kind of wiring does the house have? Is it cloth covered Romex, bx cable or is the wiring in conductor something else?
I think it's Romex. I might have time tomorrow to pull the outlet and take a picture.
 
If its two conductor Romex or knob and tube, the only way to convert to three prong is to use a GFCI. These can be installed without ground conductor.

If some outlets can be fished easily, it may be prudent to rewire or add a ground to a water pipe, assuming it is continuous metal back to earth. Even then, GFCI is prudent.

If the wiring is BX and you can verify continuity of the armor, that may be numbered in some places to a ground screw.
 
Originally Posted By: Donald
Check that your boxes have ground. Then decide how to proceed.


^ Correct ^

Grounding to the boxes is pointless if they are not grounded.
 
Originally Posted By: JHZR2
If its two conductor Romex or knob and tube, the only way to convert to three prong is to use a GFCI. These can be installed without ground conductor.

If some outlets can be fished easily, it may be prudent to rewire or add a ground to a water pipe, assuming it is continuous metal back to earth. Even then, GFCI is prudent.

If the wiring is BX and you can verify continuity of the armor, that may be numbered in some places to a ground screw.
Just searched what bx and knob and tube wiring is, It's definitely romex.

Do I use a GFCI on all outlets or to one of them? How can I tell which one?
 
Originally Posted By: Linctex
Originally Posted By: Donald
Check that your boxes have ground. Then decide how to proceed.


^ Correct ^

Grounding to the boxes is pointless if they are not grounded.
How can I check if they are grounded?
 
Just get a tester at Home Depot. About $8.50. If you get two orange lights, the outlet is property wired. Has a chart when you get different lights, also has a button to simulate GFCI trip.

http://www.homedepot.com/p/Commercial-Electric-Tools-GFCI-Outlet-Tester-Green-MS102H/206029151

You can change the outlet if there's a ground wire that leads back to the panel. Otherwise either rewire with 14/2 or 12/2 or add a third wire and wire it back to the ground bus in the panel. If it's BX armored cable, you might be able to get away with using the ground in the sheath.
 
Originally Posted By: Wolf359
Just get a tester at Home Depot. About $8.50. If you get two orange lights, the outlet is property wired. Has a chart when you get different lights, also has a button to simulate GFCI trip.

http://www.homedepot.com/p/Commercial-Electric-Tools-GFCI-Outlet-Tester-Green-MS102H/206029151

You can change the outlet if there's a ground wire that leads back to the panel. Otherwise either rewire with 14/2 or 12/2 or add a third wire and wire it back to the ground bus in the panel. If it's BX armored cable, you might be able to get away with using the ground in the sheath.



If you get one of those, and one of these (screw it in to the wallplate) it'll work.

1200px-Cheater_plug_edited.jpg


Alternatively if you have a multimeter, set it to 200v AC, put one probe in the hot and the other on the box. If it says 120v or close, it's grounded.
 
Originally Posted By: Wolf359
Just get a tester at Home Depot. About $8.50. If you get two orange lights, the outlet is property wired. Has a chart when you get different lights, also has a button to simulate GFCI trip.

http://www.homedepot.com/p/Commercial-Electric-Tools-GFCI-Outlet-Tester-Green-MS102H/206029151

You can change the outlet if there's a ground wire that leads back to the panel. Otherwise either rewire with 14/2 or 12/2 or add a third wire and wire it back to the ground bus in the panel. If it's BX armored cable, you might be able to get away with using the ground in the sheath.

Since they aren't currently grounded, should I replace one outlet with a 3 prong and put in the ground wire and then use one of these testers? I don't think the tester would do me any good with the current plugs I'm guessing.
 
You would get that two prong adapter mentioned earlier. Plug the tester into the two prong adapter and plug that into your two prong outlet. Your current two prong outlets could still be miswired. During home inspections it comes up all the time, the hot gets wired to neutral and vice versa. With the adapter, you'll just get one light, no ground. Then that just tells you to run the ground wire. If you use a GFCI outlet, you still have to put on a sticker that says no equipment ground. It simulates a ground, but it's not a real ground.
 
Originally Posted By: Wolf359
With the adapter, you'll just get one light, no ground. Then that just tells you to run the ground wire.
Run the ground wire from the outlet to the gang box or a real ground for the gang box?
 
Originally Posted By: Nick1994
Originally Posted By: Wolf359
With the adapter, you'll just get one light, no ground. Then that just tells you to run the ground wire.
Run the ground wire from the outlet to the gang box or a real ground for the gang box?


There is hot, neutral, and ground. Those are the 3 wires in the 3 prong outlet. The ground and neutral go to the same place eventually . The ground serves to carry "extra " electricity to the ground for safety. The 3rd prong must connect tho this ground wire to serve a purpose. The romex metal outer cable can serve as the ground wire if it makes its way to the ground. Therefore, the metal box itself is grounded if the romex is secure to the box on one end and the ground on the other end.

Receptacles down stream of the gfci are protected by the gfci. You have to figure out what's upstream and down stream.
 
Last edited:
Originally Posted By: Nick1994
Originally Posted By: Wolf359
With the adapter, you'll just get one light, no ground. Then that just tells you to run the ground wire.
Run the ground wire from the outlet to the gang box or a real ground for the gang box?


The tester will tell you if you have a real ground in the gang box or not. As others mentioned, if you're using BX, the gang box may be grounded. It's not preferred, but the BX goes to the panel and the panel is grounded and the metal sheath of BX cabling ends up acting as a ground. If you just have two wires going to the outlet, then regardless if the gang box is metal or not, there's no ground in the gang box. I believe technically the ground bus bar in the panel and the neutral bus bar are two separate bars, but lots of time people have both the neutral and the ground going to the same bar.

So if you have a real ground in the outlet box, then you can just run the ground wire to that outlet box, otherwise you need to run a new wire from the outlet box to the panel.
 
Ok, I used a tester I had laying around. Had a lens missing, looks like the right side lights up too. It lights up the same on all outlets I tried in the house including a GFCI in the bathroom and on the back porch. The one on the back porch I know is done properly, an electrician installed it (20 amp). So it looks like it's grounded.

You guys tell me what kind of wiring it is.



 
Hard to tell if that first light is really lit or if it's just light that's bleeding over from the 2nd. I would think it'd be brighter if it were but that may just be the picture. Looks like you have an adapter on it. Plug it into the bottom outlet so that the adapter isn't touching the screw on the two prong outlet. You should only get one center light. Then plug it into the top outlet. If the center screw is a ground, you should get two lights. Also the one that the electrician did should have 2 lights light.

Also can't tell about the wiring, if it were BX, it'd end before the outlet and you'd just see the wires in outlet as in your picture. Doesn't look like it though. A picture of the wires going into the panel would tell us if you had BX or not.
 
Originally Posted By: Wolf359
Hard to tell if that first light is really lit or if it's just light that's bleeding over from the 2nd. I would think it'd be brighter if it were but that may just be the picture. Looks like you have an adapter on it. Plug it into the bottom outlet so that the adapter isn't touching the screw on the two prong outlet. You should only get one center light. Then plug it into the top outlet. If the center screw is a ground, you should get two lights. Also the one that the electrician did should have 2 lights light.

Also can't tell about the wiring, if it were BX, it'd end before the outlet and you'd just see the wires in outlet as in your picture. Doesn't look like it though. A picture of the wires going into the panel would tell us if you had BX or not.
Thanks for the help. I think I'll get a new tester, will try to take a picture of the breaker box tomorrow if I remember. Leaving for vacation tomorrow morning for two weeks so I'll come back and hopefully will be replacing outlets.
 
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