I'm changing out some 2 prong receptacles in an old home that has no ground wire (ie, the electrical cables have a hot and neutral, no ground wire). I'd like to install new 3 prong receptacles. Is this OK? What are the implications of doing this? Thanks!

-You could replace the non-grounding type receptacle with another non-grounding type receptacle
Or
-you could replace a non-grounding type receptacle with a grounding type--where supplied through a GFCI. If you go this route, then you would have to label the receptacles supplied through the GFCI: No equipment ground and GFCI protected.
Or
-you could replace the non-grounding type receptacle with a GFCI. Label the receptacles: No Equipement Ground.
Or
-You could run a new circuit from the panel

-You could replace the non-grounding type receptacle with another non-grounding type receptacle

Good luck finding those!

-you could replace a non-grounding type receptacle with a grounding type--where supplied through a GFCI. If you go this route, then you would have to label the receptacles supplied through the GFCI: No equipment ground and GFCI protected.
Or
-you could replace the non-grounding type receptacle with a GFCI. Label the receptacles: No Equipement Ground.
Or

A very clear and concise answer. Just make sure you properly label every receptacle on the circuit.

The implication of using 3 wire outlets with out a grounding conductor is there is no safety ground wire to drain any fault currents.

The GFI method is allowed and helps to protect people from ground faults, but not having a safety ground will affect any device that must have a ground to operate, such as a surge protector.

Two wire devices are still very available at any hardware or electrical supply store.

Tk... it must be a local thing because neither Ace, Lowe's, or Home Depot have two prong outlets in stock close to my home.

"The implication of using 3 wire outlets with out a grounding conductor is there is no safety ground wire to drain any fault currents.

The GFI method is allowed and helps to protect people from ground faults, but not having a safety ground will affect any device that must have a ground to operate, such as a surge protector."

This is very true... but he doesn't have the ground available now. I believe he's after what most folks are after with this situation... the ability to plug in a 3 prong plug into a receptacle. Washington gave him the easiest and cheapest legal solution to that problem. Again, you're correct... he still doesn't have a ground. But he won't have that short of a fairly major rewire.

I haven't looked recently, but it the past my Lowe's had plenty of the 2 wire outlets. I see little good reason to use one except in the rare case of replacing an old defective one.

Thanks for all the info. Let me sum up the responses to see if I have it straight...
1) There is effectively no issue with replacing 2 prong outlets with 3 prong outlets. There is no safety ground wire to drain any fault currents but that was the case when the 2 prong outlets were in use anyway, correct?
2) I can install a GFI as the 1st outlet on the circuit and protect people from the fault current mentioned above, correct? (I understand it won't protect equipment that needs a ground though).
3) What is the significance of labeling the recepticales, I assume at the panel? Is this so that someone unfamiliar with the wiring would know that even though there's a 3 wire plug and/or GFI its still not grounded? If yes, makes sense. Thanks again!

Please do not misunderstand, there is an issue with replacing 2 wire receptacles with 3 wire, there will be no ground.

The only method allowing 3 wire outlets in place of two wire outlets is to protect the 3 wire outlets with a GFI, AND label each 3 wire outlet with the labels provided with a new GFI receptacle that state "GFI Protected" and "No Equipment Ground". This label is applied to each outlet to warn a user that there is no equipment ground, however there is GFI protection.

Using the GFI at the first outlet to protect the outlets downstream is fine, exactly what they are designed for, however, this only works if two wire cable goes from outlet to outlet.

If the home is wired with Knob & Tubing, this will not work, as the outlets are wired in parallel, or individually, rather than "daisy chain".

This, of course, is a shortcut to re-wiring the outlets with all new 3 wire cable, which would provide the protection of a safety equipment ground.

As I stated, some devices will not operate properly without an equipment ground, such as surge protector plug strips, popular with computers.

Do not get a false sense of security just because the 3 wire outlets are protected with GFI. These will help protect people from a short that energizes the metal frame or housing of appliances.

Surge protectors, and probably other devices that I cannot think of at the moment will be useless. Just today we discussed a dimmer that uses the equipment ground as a reference for the internal electronics.

Rewiring is always the best method, if at all possible or practical.

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Originally Posted by tkrussell

Please do not misunderstand, there is an issue with replacing 2 wire receptacles with 3 wire, there will be no ground.

The only method allowing 3 wire outlets in place of two wire outlets is to protect the 3 wire outlets with a GFI, AND label each 3 wire outlet with the labels provided with a new GFI receptacle that state "GFI Protected" and "No Equipment Ground". This label is applied to each outlet to warn a user that there is no equipment ground, however there is GFI protection.

Using the GFI at the first outlet to protect the outlets downstream is fine, exactly what they are designed for, however, this only works if two wire cable goes from outlet to outlet.

If the home is wired with Knob & Tubing, this will not work, as the outlets are wired in parallel, or individually, rather than "daisy chain".

This, of course, is a shortcut to re-wiring the outlets with all new 3 wire cable, which would provide the protection of a safety equipment ground.

As I stated, some devices will not operate properly without an equipment ground, such as surge protector plug strips, popular with computers.

Do not get a false sense of security just because the 3 wire outlets are protected with GFI. These will help protect people from a short that energizes the metal frame or housing of appliances.

Surge protectors, and probably other devices that I cannot think of at the moment will be useless. Just today we discussed a dimmer that uses the equipment ground as a reference for the internal electronics.

Rewiring is always the best method, if at all possible or practical.

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That's it in a nutshell. As clear and concise an answer as you could want. Please read his last sentence... that is far and away the best thing you could do for your home and loved ones.

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-You could run a new circuit from the panel

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Thank you!

:)

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Please do not misunderstand, there is an issue with replacing 2 wire receptacles with 3 wire, there will be no ground.

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Understood, but I'm not worse off than I was before correct? Meaning, if I replace the 2 wire plug which was ungrounded with a 3 wire plug which is ungrounded I'm no worse off, no better off right?

Not quite correct. As long as the GFCI is properly installed and the outlets are labeled, you have ground fault protection, so you're better off. But you won't have equipment ground... which is what you have now.

Ground fault protection makes sense. But how do I have equipment ground now with a 2 wire outlet which has no ground? Thanks!

Are you saying you have a ground? I have seen NM installed with the ground wire folded back where it enters the box and grounded by the strain relief.

Cobraguy said

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Not quite correct. As long as the GFCI is properly installed and the outlets are labeled, you have ground fault protection, so you're better off. But you won't have equipment ground... which is what you have now.

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The house has 2 prong outlets so there's no ground now. I was curious why Cobraguy said... "which is what you have now". I'm trying to understand how I have equipment ground now when there's no ground wire?

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Originally Posted by Cobraguy

Not quite correct. As long as the GFCI is properly installed and the outlets are labeled, you have ground fault protection, so you're better off. But you won't have equipment ground...which is what you have now.

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''you have ground fault protection''

Ground fault protection means that if some of the power leaks to a ground other than the neutral, the GFCI shuts the power off.


''you won't have equipment ground.''

Equipment ground means that if the power leaks to the equipment ground, it instantly overloads the breaker and it shuts the power off.


''which is what you have now.''

Might have been clearer as ''which you will still lack.'' Over all, a good post. It is tough composing answers that won't be misinterpreted. Many of mine have been.

My last post was based on you saying you have the ground. That would be possible even if the ground wire was folded back out of sight.