Going from 2 to 3 prong

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Old 08-09-09, 08:01 PM
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Going from 2 to 3 prong

My whole house has two prong plugs I recently had the electric service upgraded to 200amp. Now I want to try a swap out some of the two prong outlets for three prong ones.

Its my understanding that as long as you have three wires coming into the current two prong box that you are good to swap them out as the third wire is the ground wire, correct?

Acenti 15-Amp Duplex Receptacle-Alabaster AC215-W - Smarthome
 
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Old 08-09-09, 08:13 PM
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It is not just any three wires needed. You need a ground wire. Your options depend on how your house is wired.
If it is very old 2 wire knob and tube you only options is running ground wires back to the panel or installing GFCI devices and marking the receptacles "no equipment ground".
If it is wired with flex conduit (greenfield) you may be able to pull new grounds in the flex or install GFCI devices like above.
If you have BX (AC) steel cable. It is listed as a grounding path and all you would need to do is is install grounding pigtails or use self grounding receptacles.
Notice, I didn't mention anything about Romex. I assume if you have Romex you would have grounding receptacles.
 
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Old 08-10-09, 06:49 AM
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It is not just any three wires needed. You need a ground wire. Your options depend on how your house is wired.
If it is very old 2 wire knob and tube you only options is running ground wires back to the panel or installing GFCI devices and marking the receptacles "no equipment ground".
If it is wired with flex conduit (greenfield) you may be able to pull new grounds in the flex or install GFCI devices like above.
If you have BX (AC) steel cable. It is listed as a grounding path and all you would need to do is is install grounding pigtails or use self grounding receptacles.
Notice, I didn't mention anything about Romex. I assume if you have Romex you would have grounding receptacles.
Thanks for the reply, I know I dont have knob and tube. and there are two outlets that have already been switched over by the previous owners. So I guess I have BX (AC) steel cable?
 

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Old 08-10-09, 07:08 AM
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I know I dont have knob and tube. and there are two outlets that have already been switched over by the previous owners. So I guess I have BX (AC) steel cable?
More likely they just put grounded receptacles on an ungrounded circuit or worse and dangerous they ran a bootleg ground to neutral. Look in the attic at exposed cables to see what they are.
 
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Old 08-10-09, 06:30 PM
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Look above the panel. You should be able to see the cables or whatever wiring method you have. BX is about 1/2" in diameter. Flex conduit is closer to 1" in diameter.
 
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Old 08-10-09, 06:53 PM
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Do you have three wires in the outlet box? If so, can you describe them to us?
 
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Old 08-12-09, 02:33 PM
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Hi:

I just went though the same thing. My daughter's new (well really old) apartment outlets provided only two prong plugs, no ground. I checked; the circuits use BX cable. The ground tested fine on the all the outlets I wanted to update, so I could have used the metal BX cable. However, I decided to install GFCI outlets in any case. Better be safe than sorry. The apartment building is really old, and I am not sure I trust the cabling. The CFCI units are fairly cheap. I don’t connect the ground, and labelled the circuits “no equipment ground" with the provided labels. Now the window A/C and computers are running fine.
 
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Old 08-12-09, 07:15 PM
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Originally Posted by John Nelson View Post
Do you have three wires in the outlet box? If so, can you describe them to us?
They look like regular copper wire with a sheathing on it.
 
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Old 08-12-09, 07:34 PM
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Originally Posted by impeyr View Post
Hi:

I just went though the same thing. My daughter's new (well really old) apartment outlets provided only two prong plugs, no ground. I checked; the circuits use BX cable. The ground tested fine on the all the outlets I wanted to update, so I could have used the metal BX cable. However, I decided to install GFCI outlets in any case. Better be safe than sorry. The apartment building is really old, and I am not sure I trust the cabling. The CFCI units are fairly cheap. I don’t connect the ground, and labelled the circuits “no equipment ground" with the provided labels. Now the window A/C and computers are running fine.
The key word it come up is Apartment that part you should have get a hold of landlord first before you do anything with electrical system so best to not do it anything until talk to landlord and see if he can get qualifed electrician come out and deal with it.

Merci,Marc
 
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Old 08-16-09, 03:49 PM
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Originally Posted by tb582 View Post
They look like regular copper wire with a sheathing on it.
Anyone? I took a trip to home depot and picked up one these outlets, I think I'm going to start by changing out one of the current 3 prong outlets that has been painted over and two prong outlet
 
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Old 08-16-09, 03:56 PM
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Maybe I missed it but I haven't seen anything posted by you that indicates you can use three prong outlets.
They look like regular copper wire with a sheathing on it.
 
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