GFCI Failures + Gadgets

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The TEST button puts the R between Line Black and Load White, or the inverse. This so TEST works on GFI's with no ground. (At least on the ones I've fiddled with..)
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wroth:

there are for ordinary receptacles?
Jim
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wrote:

If you are asking about a breaker that fits in your panel, just about all current styles have a GFCI breaker.
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wroth:

    No. I was asking about the outlet receptacle type of GFCI.
    But adding a single ground fault breaker per circuit to the panel would seem to be a much better solution than adding multiple outlet type ground fault breakers.
Jim
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Breakers are the best, however they generally cost 4 to 8 times as much, and have the inconvenience of needing to go to the panel every time they trip (and they can trip often when using power outside). The GFI plugs also have terminals to wire additional plugs, lights, etc to protect things later on in the circuit.

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Jeff wrote:

Why are breakers the best?

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Because GFI breakers are at the panel, and all wiring, outlets, accessories, etc are protected, not just the ones after the GFI outlet. GFI breakers should be more reliable, especially since they are in a usually fairly controlled environment. GFI breakers are also located in one spot - if a GFI plug trips from an outlet later on in the circuit, then there may be some difficulty in locating which GFI outlet tripped, or if a normal breaker tripped from over current.

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Jeff wrote:

Ok, I see. It's not that the breaker is better, per se, it is the position it occupies in the circuit.

Ok - that's a technical reason for breakers over receptacles but only if it is true. Are GFCI breakers known to be more reliable then GFCI receptacles, to your knowledge?

So that falls under "easier to use" (or whatever you want to call it.)
Thanks! I don't necessarily agree that the points you raised make a GFI breaker better than a GFCI receptacle, but I can appreciate your rationale.
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James Meyer wrote:

A GFCI receptacle protects both itself and the circuit connected to the load side of the receptacle.

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Rip one apart and see what failed. They usually have screws on the back. All they are is a current transformer with both the hot and the neutral going through it. If the current in the neutral and the hot is not exactly the same, a current is produced in the current transformer. Most GFI's trip at a 5 mA differential, meaning a 5 or more mA current leakage from the neutral or hot will trip the GFI. Perhaps the solder joints failed from the excess thermal cycling?
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That sounded too high, so I googled for confirmation. You're right.
When I worked in the hospital, I remember the Electrical Safety Officer coming around with his cart and checking every 110Vac gizmo. His spec was 15uA. (You would marvel at this collection of cut-off molded 110V plugs.)
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Whoa! 15uA - Some insulation will collectively leak that at 120V AC especially on a humid day, and then there's stray capacitance leaking to ground!

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In

Yeah but, in the desert southwest, there ain't much in the way of stray humidity...
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The 15ua spec is the limitation of leakage current to the patient, from any piece of equipment. Not any sort of limitation for the GFCI device itself. The spec at our hospital was 15 ua., but I think the spec was 10 ua in ICU & Surgery. The specs between the leakage current safety for the patient and the amount of current necessary to trip a GFCI are basically unrelated. The two were both safety factors but for two different reasons. Even when an electrical device was grounded, there could still be minute leakage currents, that could reach the patient. These leakage currents had to be limited to below 10 or 15 microamps because patients often had devices that made more intimate contact, with the inside of the body. The skin does offer some resistance, however even a range of microamps, could be fatal if connected internally.
I was a Biomedical Engineer/Safety engineer at a hospital for three years. I had to test EVERY outlet and service almost every piece of electrical/medical equipment in the hospital. The adjustable GFCI tester I used was calibrated in ma and 99% on the GFCIs would trip as the knob reached 3ma. They were click settings as opposed to a pot.
The first part of the input of the sensor for the GFCI was a toroid transformer with three windings. The first two (I will call the main) windings were wound as current opposing, around the toroid. Such that if the two main windings(Hot & Neutral Lines) had the exact same amount of current passing through them, they would cancel each other and no output would be present at the third winding. The third winding was connected to the differential inputs of an op-amp. If there was any imbalance of current between the hot and neutral lines, the imbalance would negate the cancellation and a current would be induced in the third winding of the toroid, biasing the op-amp and in turn triggering the relay to break the power circuit. The imbalance would be indicative of current taking an inappropriate path to earth, through a path other than the neutral line of that same outlet.
The statement that no safety ground line is required for the GFCI to operate the way it was meant to, is true. However the test button would not operate, because the test button put a resistor from the hot line, to the safety ground line as a test, to cause the imbalance in the hot and neutral lines. Even if no safety ground line was connected to the given outlet, any amount of leakage above 2 or 3 ma, to another path to earth, such as a waterpipe, would be measured, as an imbalance in the toroid transformer, flip the output of the op-amp and in turn, trip the relay. A safety ground is not necessary for a GFCI to operate normally, but of course it would be stupid not to have a safety ground in any event.
buck
(this post was read in alt.binaries.schematics.electronics)
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Jim Thompson wrote:

The environment, and lack of testing, kills GFCI receptacles installed outdoors. GFCI receptacles should be tested once a month, per manufacturer's instructions. They have two general categories of failure: electronic and mechanical. Mechanical: the electronics operates a solenoid, which operates the mechanical mechanism to open the contacts. Heat/cold, humidity, dirt all can combine to gum up the mechanical works - and that is particularly true outdoors where there is more of all of those than indoors. When you perform monthly testing, the mechanical mechanism is less prone to freezing up due to the accumulation of gunk. Electronic failure is also exacerbated by outdoor installation, for the same three factors - heat/cold, humidity and dirt. Heat harms electronics, temperature changes cause expansion/ contraction, humidity and dirt combine to form resistive gunk.
Note that I did not mention surges. I do not mean to say that a surge could not be involved - I just want to exclude that from the environmental factors I am talking about.
Install GFCI receptacles indoors to protect the outdoor receptacles. It is a far better approach. The downside is that a trip of the GFCI requires a walk inside to reset it.
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Didn't you use the appropriate colored wires?
And as to why they didn't last you don't give us enough details. There are different grades of receptacles. Plus being put outdoors certainly does not help. I have no idea how good the housing is and if it leaks. Plus I have no idea if the GFCI's that broke were cheap ones made in China.
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On 17 Nov 2003 12:22:31 -0800, scott snipped-for-privacy@my-deja.com (Childfree Scott) wrote:

Two circuits, each common is white. Have to be paired correctly thru the GFCI.
Housing is standard metal outdoor/wet-location box.
Malaysia. The new ones are made in Mexico :-(
...Jim Thompson
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On 17 Nov 2003 12:22:31 -0800, scott snipped-for-privacy@my-deja.com (Childfree Scott) wrote:

Should have also noted: The wiring in question was pre-placed for expansion and capped off with wire nuts. So now I have to pair off the black and red with the proper white, otherwise the GFCIs will trip on any load.
...Jim Thompson
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On Sat, 15 Nov 2003 15:44:40 -0700, Jim Thompson

That is why the electric company should install a GFCI up on the pole at the transformer. That way, everyone and everything is protected in the whole neighborhood.
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Good idea if only using theoretical knowledge. Bad in reality. It is a classical example of why decisions based only upon theory are not sufficient. It is why they teach in high school science the concepts. Required is both the theoretical concepts AND experiment confirmation. Why is the refrigerator, specifically demanded by code, not on a GFCI? Because GFCIs are good in some places and not desirable in others - as has been proven by experience. A blown GFCI on a refrigerator can create food poisoning - something learned by field experiments.
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