Two wire house... again

[Brad Smith]

Just read this:

Sec. 210-7(d)(3) permits any of the following installations when replacing a 2-wire ungrounded receptacle:

(a) Replace it with another 2-wire receptacle;

(b) Replace it with a GFCI-type receptacle and mark the receptacle with the words “No Equipment Ground;” or

(c) Replace it with a grounding-type receptacle protected by a GFCI device (circuit breaker or receptacle). Since the grounding terminals for the receptacles are not grounded, you must mark the receptacles with the words “GFCI Protected” and “No Equipment Ground”

What about the face plates if they aren't GFCI's, do they need to be two prong? 

Do you put these "No Equipment Ground" labels on your receptacles?

[Steve Babiak]

Originally posted by @Don Meinke:

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That being said back to original post, subject,  how do you wire a gfi outlet into a 2 wire system and make it trip if there is a ground fault issue???  Do you HAVE to string a new bare wire from the box? Or is that just preferable if possible?

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Ah, you have been exposed to the myth that a GFCI must have a ground wire in order to function as a ground fault protection device. That is a myth. The GFCI functions by sensing the amount of current in the hot and the amount of current in the neutral, and if those two currents do not match to within some small difference a ground fault is "declared" and the device trips - the ground current is not measured, it is assumed to be the difference between hot and neutral currents. As such, GFCIs are allowed by code to be ungrounded if properly labelled as such; appropriate labels are often found inside the packaging with the GFCI. 

And you can test that if you choose by disconnecting temporarily the ground wire from a GFCI and pushing the test button, and it should trip. 

Now, there are GFCI testers that are inserted into a receptacle to test the GFCI; if the GFCI is ungrounded, those testers will not trip the GFCI. Some would conclude from that that the GFCI is not protecting from ground faults, but pressing the test button on the GFCI is the only reliable test method.