2 prong to 3 prong conversion


Old 10-14-00, 08:07 PM
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I was told that I could convert my 2 prong a/c outlets to 3 prong? Is this correct and how is it done? Thank you.
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Old 10-15-00, 09:17 AM
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The answer is yes, with some "ifs" that are important. First, if the 2-prong outlets are installed in boxes that have a ground wire in them, or the boxes themselves are grounded, then it is simply a question of replacing the outlets with the 3-prong type and connecting the ground. So, you need to determine if a ground is present by testing.

Second, if there is no ground present at the outlets' boxes, then you have 2 choices. You can run new wiring with a grounding conductor and hook it up as normal, or you can find the first outlet on each circuit and install a GFCI outlet. This allows you to have ungrounded 3-prong outlets on the remainder of the circuit. These should be marked because there is no true ground provided and that is significant for some types of equipment and especially surge suppressors.

Testing for ground is fairly simple. First, turn off the breaker for the circuit you want to test. Remove the outlet from the box, but leave it attached to the wires. Look inside the box to see if there is a bare wire inside. If so, pull it out where you can reach it with a voltage tester, but not touching the outlet. Now, turn the breaker back on, and check for a voltage reading between the black lead side of the outlet and the bare wire, and/or the box. If you get a 120 volt reading, then you have a ground and you can install 3-prong outlets.
If there is no bare wire, the the box is grounded, then you need to get "self grounding" outlets.
Old 10-15-00, 10:18 PM
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yes u can convert your current 2 blade outlets to 3 prong grounded outlets useing 1 of the following methods.
1. you may simply chaing out the existing 2 prong to 3 prong if u have a grounded system . best way to tell if u have a grounded system is remove the panel cover and look 4 bare copper wires attached in the panel, if u have none then u dont have a grounded system, and must use 1 of the other methods.
2. install a gfci outlet on the first outlet on the circuit and line load it, and then install the 3 prong outlets and label them gfci procted no equpiment ground. this provides persional proctection only no ground path.
3. pull in new romex that contains a ground , and install a ground rod if 1 isnt present.
4. pull in a ground wire and a ground rod if not present. same amount of work as new romex.
Old 10-17-00, 07:55 PM
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Rank and Sparky,

I thought that I might point out that both replies spoke of connecting to the first receptacle on the circuit. I am afraid that we may be confusing the answers in this particular wiring method.

90% of the wiring that does not have a grounding conductor is not designed with a receptacle to receptacle wiring design. 90% of the wiring styles performed back when the wiring, as accepted practice, was to install the wiring without a grounding conductor in the cable was the old cloth style and BX style wiring method. This wiring was installed at that time by running from the panel to a light fixture and branching out to all the receptacles from that light fixture. The receptacles were not wired loop de loop under normal occasion. This wiring style makes it impossible to install a GFI receptacle on the first receptacle. There is not normally a first receptacle in this type of wiring style.
This is why I frequently refer to installing the GFI receptacle under the panel and running the branch circuit from the breaker or fuse through the GFI receptacle then connect the branch circuit to the load side of that GFI. This way all receptacles will be GFI protected.

If we try to install a GFI on the first receptacle on that circuit when there in normally no first receptacle on that circuit, then most receptacles on that circuit will not be under that GFI receptacle.

Good luck

Old 10-18-00, 12:12 PM
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Thanks wgoodrich for mentioning the trick of installing GFCI outlets at the breaker/fuse box. I've seen you mention it before, and I almost suggested it this time. I really like that method, and am planning to do that very thing on some of my circuits at home.
Old 10-21-00, 03:36 PM
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In old wiring though didn't the steel covering on the BX wire act as the ground wire? If so wouldn't the 3 prong outlet be grounded as long as the boxes are metal? Tim

[This message has been edited by Magoo (edited October 21, 2000).]
Old 10-22-00, 09:23 AM
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If you looked at existing then they probably did use the BX flex as a grounding source. This is the era that the grounding conductor system was introduced.

However when we are currently installing three prong receptacles then we must meet current NEC requiremenst. The 99 NEC limits the use of flexible conduit being used as a grounding path to 6' only. This would eliminate the inspector from allowing the steel of the flex to be recognized as an approved grounding path.

You do have a good point. I wonder regardless of the minimums, considering engineering principles, I believe the the steel flex would be better than no grounding path. I also wounder considering the fast pace of technology, if the flex used as a grounding path better than the GFI C-board monitering the grounding of the equipment?

It is something to think on.

Hope this helps


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