Can you install a GFIC outlet in place of an old ungrounded outlet and dispense with the need of trying to run a ground wire from that outlet into the crawl space to some water pipe, and assum that the GFI will now function as the local circuit breaker if a problem were to later develop on that cucuit?
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Yes, NEC allows this. However, this provides protection for people, not equipment - so the circuit will be safe for you, but will not allow the surge protector for your computer to function correctly.
If your wiring is armored cable, you can also use the cable armor as the ground. I don't recommend it, because it is often not a good ground, but NEC allows it.
Just reread your message - a water pipe is NOT a good ground. If you end up running a ground wire, run it to a good ground such as a ground rod, not a water pipe.
Edited 6/30/2009 6:14 am ET by woodturner9
Ok and thanks for the water pipe advice, I was sort of remembering something about bonding at the water heater and sure didn't want to deal with pounding a ten foot ground rod into the soil near the house.
"Can you install a GFIC outlet in place of an old ungrounded outlet and dispense with the need of trying to run a ground wire from that outlet into the crawl space to some water pipe, and assum that the GFI will now function as the local circuit breaker if a problem were to later develop on that cucuit?"
You can install a GFCI on an ungrounded circuit and also use it to protected downstream grounding TYPE receptacles. In this the case the GFCI receptacle, and any downstream receptacles, are supposed to be marked No Equipment Ground. And the individual package of GFCI's include some labels, but they are never used.
But it does not provide a "ground".
Here are some details.
First of all it is no longer code, and in fact can be dangerous, to run a ground wire "some water pipe". The reason is that metal piping or sections are often replaced with plastic. Also shock hazard for any working on the pipes.
A ground wire can be run to another box with an equipment ground conductor, including the main panel. Or to any point on the ground electrode system.
And if the house had metallic underground metallic water pipe that is at least 10 ft long then it must be used at part of the ground electrode system, but it can only be connected on the first 5 ft of where it enters the house. And if the water piping is metallic on the inside, but not on the outside then the water piping must be bonded (electrically connected) to the ground electrode system.
Now to the what the GFCI does and what grounds (equipment grounding conductors, what connected to the 3rd pin in a grounded receptacle).
If you have a piece of equipment with and a fault (short) develops between the hot lead and metallic case then if anyone touches the case while touching some grounded object can get a shock.
A device with a ground wire and plugged into a grounded receptacle the equipment grounding conductor, "the ground wire", is connect back to the neutral conductor at the service entrance, which is usually the main panel.
With a equipment grounding conductor the fault current with flow back to the panel. And if there is a dead short the current will be high enough to trip the breaker. And even if the resistance is high enough that only a small amount of current flows the ground keeps the case at zero voltage with respect to another other surfaces that are grounded and thus safe.
However, most portable household equipment is double insulated. Either the case is plastic or there are two different types of insulation between electrical parts and any touchable metal so that even if there is a fault the user can't touch anything that would shock them. These don't have grounding plugs.
The GFCI works by measuring the difference between the hot lead and the neutral lead. And if they differ by more than 0.005 amps it will trip. Now on a double insulated appliance there is no path for ground current to flow and thus the GFCI would not trip immediately.
If it is a grounded appliance then it would trip immediately if the cord and plug where good (IE, ground pin not cut off, or wire broken by wear) and it is a true grounded receptacle.
However, in either case if you drop something into water you can still get currents from the hot side to water and anyone that might been in contact with the water.
That is why GFCI's are required in bathroom and kitchen countertops.
So in terms of personal safety either a true ground or a GFCI end up doing the same thing.
However, GFCI's can false trip from the electrical noise from motors. While modern GFCI's are much, much less to do this it is still recommended that critical appliances, such as refigerators, not be used on GFCI protected circuits if possible. Note that modern refigerators also have been insulation. Older ones often has small amounts of leakage which would trip GFCI's and helped give then a bad name.
But true grounds also serve another purpose. For surges they are used to help maintain hot and neutral at the their nominal voltage levels during a surge when used with surge protectors.
So for anything connected to a surge protector you need a true ground to get maximum protection.
William the Geezer, the sequel to Billy the Kid - Shoe
Congratulations!
BillHartmann receives the 'Breaktime Achievement Award' for continued efforts in assisting those in need.
Saaalute! View ImageView Image
Edited 6/30/2009 2:43 pm ET by rez
I can't believe how many times he's repeated that (important) treatise. I figure he must have it stashed somewhere and then copy/paste. ;)Scott.
Never got organized enough to do that.And I am now on a different computer (actually OS and can't access all of my stuff)And I like to respond to the specific message as it often has different needs or understanding.But I should setup some boiler plate. Well one of these days..
William the Geezer, the sequel to Billy the Kid - Shoe
yeah,
BT needs a dozen more like him in different fields.
Boss has been out in his field at times. Does that count?
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
receives the 'Breaktime Achievement Award' for continued efforts in assisting those in need.
What??? I don't get a kudo for my earlier and accurate post? ;-)
kudos for sure.
Helping field questions from the posters is part of the bread and butter to what keeps the forum alive and functioning in the positive.
be positive
Edited 6/30/2009 8:29 pm ET by rez
Someone should also give him an award for the longest, most drawn out posts.
Long, drawn out posts........
and if you read them, you might actually learn something useful.
JimNever underestimate the value of a sharp pencil or good light.
I enjoy learning things, but I'd rather spend less time to learn them. Some people don't know when to stop typing!
Trust me, I enjoy breaktime, I like reading the threads, and I almost always learn something, but let's face it, some people write too much. It's like a speed bump in the middle of the highway!
Alright, I know I was being mean, must've been in a bad mood.
"Some people don't know when to stop typing!"
Well, and sometimes people want a simple answer when a simple answer just won't do. Sometimes questions require a more detailed answer than the asker wants to hear, but there's no helping it. That just means the asker doesn't even know enough to frame the question properly, let alone understand the answer. In this case, every bit of info that was provided was important, maybe even critically important, depending on the use of the outlet in question.
And, just because you're plugging a vacuum cleaner into the outlet today is no reason to be sure that the outlet will never be used for, say, a computer. But I happen to be one of the 3 people on the planet who actually uses the stickers that come with GFI's, so YMMV.Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.
Le'mme see, the white wire goes on the brass colored screw...no wait...maybe it's to the little green one at the top...or is that the bottom?
Main question: "Can you install a GFCI where an ungrounded outlet is?"
Quick answer: "Yes"
Or
Slow drawn out "thread bogging" answer: See post #3
(sorry, I couldn't help myself, had the day off!)
Ok that's a lot of info. Sounds like my limited application for a bedroom (near the bed) circuit, and not near any water source could be served by a GFIC. I don't anticipate any large appliance being run off of these circuits either so not too worried about your caveat re "noise". Anyway thanks for the treatise...