Installing GFCI in garage with no ground

[Charles J. Yezza]

Originally Posted by dvalley

Wow,

You two are really getting deep with this GFCI situation. I'm learning quite a bit on this thread. Thanks to the both of you.

You got that right, and all I was asking was the correct way to install a GFCI on a ungrounded circuit.

I went back and fixed per suggestion. My 3-light tester showed the circuit as being grounded, my sure tester showed and un-grounded circuit. I learned from this post. Thanks to all the inputs. I may not use that chaep tester anymore as it definitely fooled me!!!!!!!!!!!!

[Greg Fretwell]

The sure test looks for a low impedance path (<1 ohm), the 3 light tester only shows you have enough of a path to light a neon. (meg ohms).

[Greg Fretwell]

Mike nobody picked up on my question, what do you think?
With a 2 wire circuit to the garage, couldn't the installer drive a rod and connect the ground to the neutral?
(no other metalic paths) 250.32(B)(2)

Nothing in that rule says it has to be a feeder, it can be a single branch circuit.

[Paul W. Abernathy]

Running to DC to catch a flight and wish I had gotten in on this earlier.....seems very interesting...

I will say this......the Earth is never to be considered an effective path to do anything.....driving a rod at a building, lamp post and what have you has nothing to do with the electrical system....serves no viable function in the electrical system as it pertains to the dwelling...other than lightning and surges...and in regards to 250.32(B)(2)...more so Lightning.

It is essential to provide an effective fault path to clear OCPD's.....in regards to GFCI's...they detect leakage which results in a magnetic field in the transformer of the GFCI resulting in the circuitry to cut out.....leakage of 4-6mA will cause it to open......leakage because of improper installation, bad equipment, improper connections and so on will make the GFCI activate and is part of the sources for nusi. tripping....

Ok....gotta run......flight leaves in 3 hours and I have a 2 hour trip...Oh....No Greg.......the exception to 250.32(B)(2) still provides this path....via the grounded conductor...but you knew that.....later fellas.....have fun.

[Greg Fretwell]

I never said a ground rod alone would open the breaker on a fault, nor was that my intent. Only that it would operate the GFCI on a bolted fault like they had in the garage door scenario.
My 250.32(B)(2) was directed at the top note in this thread and yes you are using the grounded conductor as the grounding path, specifically allowed in this situation ... until the 2008 is adopted.

Mike was implying that in the desert he lives in it would take over 800 8' ground rods (at >20,000 each) to get under 25 ohms. I knew they had a drought but I didn't realize it was that bad

[Mike Whitt]

Originally Posted by Greg Fretwell

Mike nobody picked up on my question, what do you think?
With a 2 wire circuit to the garage, couldn't the installer drive a rod and connect the ground to the neutral?
(no other metalic paths) 250.32(B)(2)

Nothing in that rule says it has to be a feeder, it can be a single branch circuit.

(2) Grounded Conductor. Where (1) an equipment grounding conductor is not run with the supply to the building or structure, (2) there are no continuous metallic paths bonded to the grounding system in each building or structure involved, and (3) ground-fault protection of equipment has not been installed on the supply side of the feeder(s), the grounded conductor run with the supply to the building or structure shall be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The size of the grounded conductor shall not be smaller than the larger of either of the following:

Othere sections of the NEC would not allow the connection of the electrode system to the neutral of a branch circuit any where on the system.

The allowance to bond to the neutral at the second building is not the only allowance in the NEC for allowing the neutral to act as an equipment grounding conductor. See 250.140

[Greg Fretwell]

I suppose we could argue about this for a month or two but the phrase you highlighted was about GFCI protection, not defining what they mean by "supply". If they meant "feeder" to the exclusion of branch circuits why didn't they use that word at the top of the article? It is really a moot point since the whole thing was deleted in the 2008 code.
As far as I know this was the last place that allowed the neutral to also act as the EGC on the line side of the service disconnect.

[Mike Whitt]

Originally Posted by Greg Fretwell

the phrase you highlighted was about GFCI protection,

They are not talking about GFCI protection but instead they are referring to GFPE or equipment fault protection (shunt trip breaker)

Originally Posted by Greg Fretwell

not defining what they mean by "supply". If they meant "feeder" to the exclusion of branch circuits why didn't they use that word at the top of the article?

There was no need to as the grounding of the neutral must be in the service equipment. This is one of the reasons for 225.36

Originally Posted by Greg Fretwell

It is really a moot point since the whole thing was deleted in the 2008 code.

and in my opinion it is a good thing that they did.

Originally Posted by Greg Fretwell

As far as I know this was the last place that allowed the neutral to also act as the EGC on the line side of the service disconnect.

See 250.140 for another place this is allowed.

[Paul W. Abernathy]

I just wanted to interject and say....I LOVE you guys......thehehehehe