# Radon fan tripping GFCI



## MTW (Aug 28, 2013)

As much as I like Leviton, was it a Leviton GFCI? And was it WR?

Out of curiosity, why is a radon fan being GFI protected? There is no need for that, code wise.


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## MDShunk (Jan 7, 2007)

MTW said:


> As much as I like Leviton, was it a Leviton GFCI? And was it WR?
> 
> Out of curiosity, why is a radon fan being GFI protected? There is no need for that, code wise.


Some are cord and plug connected


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## WronGun (Oct 18, 2013)

MDShunk said:


> Some are cord and plug connected




It’s a leviton WR, about 200 Installed in the last year with no issues.

I use taymac pvc boxes with the taymac gasketed in-use covers I even siliconed the foam going around where the box meets the cover 

It’s GFCI Protected because it’s an exterior Receptacle 


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## MDShunk (Jan 7, 2007)

Do you have the equipment to accurately measure the current on L1 and compare it to the current on the neutral? I'm betting money bad fan. They only last but so long. I never did radon remediation, but I've replaced a heck of a lot of radon fans that went bad over the years. In truth, if they had a cord, I'd put a knockout in the peckerhead and run sealtite if it was outdoors. I only used the corded ones in basements or attics.


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## MTW (Aug 28, 2013)

MDShunk said:


> Some are cord and plug connected


Interesting. I've never seen that. All the radon companies hard wire them here.


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## splatz (May 23, 2015)

When you say the GFCIs are failing, what happens? Will they hold unloaded or with a known good load?


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## eddy current (Feb 28, 2009)

Hardwire it, no GFI. Never have to go back


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## paulengr (Oct 8, 2017)

Most motors end life as a ground fault. Bearings fail and scuff the insulation, or it gets moisture in it, or the shaft gets damaged, or a surge wipes out the insulation, or just maybe it survives all that and the insulation gives way from old age. That’s why the first motor test is almost always a Megger.


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## trentonmakes (Mar 21, 2017)

eddy current said:


> Hardwire it, no GFI. Never have to go back


This

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## Helmut (May 7, 2014)

All the radon fans I've seen are plastic housings. Seems like the same logic as mandating GFI cords for use with double insulated, two prong power tools.

What the real reason for it?


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## J F Go (Mar 1, 2014)

If you can't hard wire it I'd put in a single receptacle and install a GFCI breaker. I very much dislike GFCI receptacles and will never again install one.


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## Paul S. (Sep 8, 2012)

I like the idea of insulation testing the motor. Also, do an insulation test on the circuit. I had a customer that was operating a treadmill on a circuit installed by others. He thought he was overloading his circuit. I told him that wasn't his problem. I checked the circuit and found two small cuts in the wiring insulation at the back of the outlet box, (probably from someone's razor blade.) The more current you draw, the more likely that current will leak through compromised wiring. I then put some tape over the cuts and the circuit has been operating normally ever since as far as I know.


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## gpop (May 14, 2018)

WronGun said:


> I’m getting annoyed now... I’m going back for my third warranty call for an exterior GFCI that keeps failing, it is being used for a radon fan.
> 
> Everything is newly installed in the house. The service all the way to the dedicated radon fan GFCI.
> 
> ...


If the only fix is to replace the gfci you would have thought that there would be some sort of sign. If the gfci is dry with no arc marks the chances are the gfci should still reset with the load disconnected which would indicate a fault with the load rather than the gfci. 

I have seen something odd like this but that was a one in a million where the long bottom screw just happened to be perfectly lined up with the back of a wire nut.


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## lighterup (Jun 14, 2013)

Paul S. said:


> I like the idea of insulation testing the motor. Also, do an insulation test on the circuit. I had a customer that was operating a treadmill on a circuit installed by others. He thought he was overloading his circuit. I told him that wasn't his problem. I checked the circuit and *found two small cuts in the wiring insulation at the back of the outlet box*, (probably from someone's razor blade.) The more current you draw, the more likely that current will leak through compromised wiring. I then put some tape over the cuts and the circuit has been operating normally ever since as far as I know.


Could you explain why this would be current leak? It's in a box.
Don't we strip insulation off of thhn all the time in order to wrap
the copper around the _termination screw_?...and by doing this
is this a point of current leakage?

I've never heard of this before and am interested in further 
knowledge on the matter


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## MDShunk (Jan 7, 2007)

lighterup said:


> Could you explain why this would be current leak? It's in a box.
> Don't we strip insulation off of thhn all the time in order to wrap
> the copper around the _termination screw_?...and by doing this
> is this a point of current leakage?
> ...


Glad you said it and not me. I don't want to dogpile. :wink:


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## lighterup (Jun 14, 2013)

I was told (by an electrical inspector) that taping 
around the terminal screws was a violation.

Whether it is an actual violation or not ..IDK ,
but if it in fact is , I guess taping around the
terminal crews to stop current leakage isn't 
an option..soooo what to do?

Fork connectors?


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## trentonmakes (Mar 21, 2017)

I always tape terminal screws when installing in a metal box.
Never heard of it being a violation???


lighterup said:


> I was told (by an electrical inspector) that taping
> around the terminal screws was a violation.
> 
> Whether it is an actual violation or not ..IDK ,
> ...


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## splatz (May 23, 2015)

Unlike the exposed terminals on receptacles nicks are sneaky, they might not even be visible until the wires are folded up, then they wind up in the wrong spot, touching or just-about-touching something conductive. 

You can wind up with a high impedance short rather than a dead short that just trips if there's a conductive path through dirt, condensation, etc. in there. The megger would know. It's not the load but the voltage that determines whether it conducts. 

(I am assuming the nicks in the wires were on the load side of the receptacle, they might leak but it wouldn't trip the GFCI on the line side.)

There's no leakage out the bare terminals under normal circumstances they are far from each other. If there was, there would be leakage from the load side terminals on the GFCI receptacle to the ground receptacle and they'd trip. (OK so theoretically there might be some infinitesimal current flowing across the air gap but in real terms no leakage, zero for practical purposes, nowhere near the 4-6ma that trips a GFCI.) 

I think that inspector was wrong about taping around the receptacles current screws, I'd swear I even saw that as optional in the instructions. I think most agree it's not a bad idea with metal boxes.


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## paulengr (Oct 8, 2017)

Taping under screws is a problem, over is fine. In fact it probably seems obvious when in doubt, insulate.

It’s not a Code violation and if you think of the traditional motor termination (bolted lugs) on NEMA motors, taping is the rule not the exception.

There are two problems with taping lots of things. First you can’t inspect it so this is like getting an inspection before sheet rocking vs. after. There are no violations but it can’t be inspected. So there is no easy way to see the wire color, see if it’s wrapped 270 degrees, or the insulation is trapped under the screw, or if the screw was tightened. The second issue is you can’t easily troubleshoot something all taped up...can’t easily inspect or put probes on it.

Plus in metal boxes over time tape doesn’t stop anything. I can’t tell you how many dozens of motor leads have failed at the peckerhead where it chafed right through tape, even if some idiot felt the urge to make a giant tape ball instead of securing the leads so they don’t rub or using duct seal or mastic to secure things. 3M is pretty clear on how to use their product to tape motor leads.


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## splatz (May 23, 2015)

paulengr said:


> Plus in metal boxes over time tape doesn’t stop anything. I can’t tell you how many dozens of motor leads have failed at the peckerhead where it chafed right through tape,


That's totally different from a receptacle though. With a receptacle, you're just taping to prevent incidental shorts from the terminals to the box when the cover is off. 

There are receptacles with no terminals, gets around the whole problem


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## eddy current (Feb 28, 2009)

When I see a receptacle that has tape wrapped around it my first thought is that it was not installed by a professional.
When the receptacle is attached to the box the terminal screws can not touch the box, so why tape it?


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## splatz (May 23, 2015)

eddy current said:


> When I see a receptacle that has tape wrapped around it my first thought is that it was not installed by a professional.


Although that is usually accurate, I don't really see anything wrong with it. 

Now wrapping a wire nut in tape, that bothers me, for whatever reason.


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## Paul S. (Sep 8, 2012)

lighterup said:


> Paul S. said:
> 
> 
> > I like the idea of insulation testing the motor. Also, do an insulation test on the circuit. I had a customer that was operating a treadmill on a circuit installed by others. He thought he was overloading his circuit. I told him that wasn't his problem. I checked the circuit and *found two small cuts in the wiring insulation at the back of the outlet box*, (probably from someone's razor blade.) The more current you draw, the more likely that current will leak through compromised wiring. I then put some tape over the cuts and the circuit has been operating normally ever since as far as I know.
> ...


This was some small cuts on a piece of NM cable. Sometimes, when taking the outer 
layer off, people cut too deeply and cut into the actual conductor insulation. When the conductors are right next to each other, or next to the ground, having cuts in the sheathing can allow current to leak. I hope that makes sense now.


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## gpop (May 14, 2018)

eddy current said:


> When I see a receptacle that has tape wrapped around it my first thought is that it was not installed by a professional.
> When the receptacle is attached to the box the terminal screws can not touch the box, so why tape it?



yep and none of us would ever change a receptacle live


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## Wirenuting (Sep 12, 2010)

About the only time I’ll wrap a receptacle is in a box using Madison straps. 
I never wrap ones outside, the tape gives moisture a place to collect.
Seems the past 10 years or so, I’ve seen more screws rusting and corroding. Cheaper metal from China?


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## sbrn33 (Mar 15, 2007)

lighterup said:


> I was told (by an electrical inspector) that taping
> around the terminal screws was a violation.
> 
> Whether it is an actual violation or not ..IDK ,
> ...


This could very well be the worst attempt at a troll post I have seen since rewire.


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## lighterup (Jun 14, 2013)

sbrn33 said:


> This could very well be the worst attempt at a troll post I have seen since rewire.


who me ?


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## lighterup (Jun 14, 2013)

eddy current said:


> When I see a receptacle that has tape wrapped around it my first thought is that it was not installed by a professional.
> When the receptacle is attached to the box the terminal screws can not touch the box, so why tape it?


so current leakage doesn't create a magnetic field 
from the screw to the side of the metal box....









:vs_laugh:Now that was a troll post there SBRN


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## MDShunk (Jan 7, 2007)

Paul S. said:


> This was some small cuts on a piece of NM cable. Sometimes, when taking the outer
> layer off, people cut too deeply and cut into the actual conductor insulation. When the conductors are right next to each other, or next to the ground, having cuts in the sheathing can allow current to leak. I hope that makes sense now.


It only makes sense if you changes some of the laws of physics that apply to electricity.


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## Paul S. (Sep 8, 2012)

MDShunk said:


> Paul S. said:
> 
> 
> > This was some small cuts on a piece of NM cable. Sometimes, when taking the outer
> ...


Okay, I'm not sure where the confusion is. What usually happens when you have cracked and brittle, damaged, conductor insulation?


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## MDShunk (Jan 7, 2007)

Paul S. said:


> Okay, I'm not sure where the confusion is. What usually happens when you have cracked and brittle, damaged, conductor insulation?


Until the metallic surfaces physically touch, assuming we're talking about voltages encountered in a dry interior of a dwelling, absolutely nothing.


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## lighterup (Jun 14, 2013)

Paul S. said:


> Okay, I'm not sure where the confusion is. What usually happens when you have cracked and brittle, damaged, conductor insulation?


please continue...
What happens with cracked , brittle insulation dries up , flakes off
into a form of blackened dirty dust?

BTW
I've rewired homes where the K&T did just this leaving
nothing but the bare wire between each insulator.

What was left was a coating on the floors and in the walls
of the remnant dust it turned into. House had zero insulation
either in the attic or walls , so I'm sure this helped expedite 
the process.

It was actually my selling point to convince the HO to get the job.


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## active1 (Dec 29, 2009)

eddy current said:


> When I see a receptacle that has tape wrapped around it my first thought is that it was not installed by a professional.
> When the receptacle is attached to the box the terminal screws can not touch the box, so why tape it?


I don't wrap tape around rec in new construction.
But for service working hot, always.

Pushing it in it can easily bump the mudring.
That can create 2 more problems.
What else tripped and where is the panel & breaker for this.
In a big facility it can cost an hour looking for the panel and or trying to get access to a room someone put a panel in.

Worse is if it's a switch on a 277v circuit and the distribution breakers are turned down low.
Half the power could be knocked out on 1 floor or more.


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## trentonmakes (Mar 21, 2017)

eddy current said:


> When I see a receptacle that has tape wrapped around it my first thought is that it was not installed by a professional.
> When the receptacle is attached to the box the terminal screws can not touch the box, so why tape it?


Handy boxes and old metal boxes are a close fit, so I tape em up as an added precaution and it helps me sleep better at night.
I dont really need any beauty rest, its more of a peace of mind thing.

My old boss would tape up outdoor receptacles in a plastic weatherproof box. Lol
I never did and always got bitched at for it. I did use tape if it was a metalbox. Again, peace of mind and just something I got used to doing.

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## Bird dog (Oct 27, 2015)

trentonmakes said:


> Handy boxes and old metal boxes are a close fit, so I tape em up as an added precaution and it helps me sleep better at night.
> I dont really need any beauty rest, its more of a peace of mind thing.
> 
> My old boss would tape up outdoor receptacles in a plastic weatherproof box. Lol
> ...


First time the power is turned on there are fewer shorts to track down.


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## Paul S. (Sep 8, 2012)

MDShunk said:


> Paul S. said:
> 
> 
> > Okay, I'm not sure where the confusion is. What usually happens when you have cracked and brittle, damaged, conductor insulation?
> ...


Well, I don't want to disagree with you because I am assuming you are more experienced than I am. But, as I stated earlier, I did have a customer who had two small cuts on the wires that were connected to the load side of a GFCI. The GFCI would reset with no problems. However, when a load was attached, which in this case was his treadmill, after an amount of time, the GFCI would trip. After separating these wires, and taping over the areas that were the insulation was cut, the treadmill would work just fine and would not trip the GFCI. Perhaps I made an assumption. My assumption would have been that, as more current was drawn by the motor on the treadmill, the more likely it was to leak to ground through those small cuts in the insulation. All I did to correct the problem, was to separate the two wires where the insulation had been compromised, tape over the insulation, and everything was fine after that. If my assumption is wrong, please explain that, if you will. I would like to learn something if that's what needs to happen. I guess I would also have to ask if what you stated is true then why do we do insulation testing? What does it matter if the insulation is poor or not or has a low resistance as long as the conductors are not physically touching there should be no problems. I'm definitely not asking this in a smarty pants way either; again, if I need to learn something then I want to learn it or better understand it. Thanks in advance.


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## trentonmakes (Mar 21, 2017)

Maybe the wires were touching or barely touching and you taping them remedied that situation?

Old dry brittle insulation will still work without issue until it contacts something. Many older homes still have these wiring and do not have nuisance trips. Doesnt necessarily mean its a good thing.

The point was, that alone will not trip the gfi.

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## Paul S. (Sep 8, 2012)

trentonmakes said:


> Maybe the wires were touching or barely touching and you taping them remedied that situation?
> 
> Old dry brittle insulation will still work without issue until it contacts something. Many older homes still have these wiring and do not have nuisance trips. Doesnt necessarily mean its a good thing.
> 
> ...


I assume that is correct, that the wires were barely touching each other, just enough to cause a problem under a heavier load. I understand that old dry insulation will not alone trip the GFCI. (We have bare conductors and terminations all over the place...) My original point, or thought, was that an insulation test might show some weakness somewhere that might not be able to be easily seen with the eyes. Whether there's a fault with the motor, or on the circuit wiring, or even in the cord that goes to the motor.


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## gpop (May 14, 2018)

Paul S. said:


> Well, I don't want to disagree with you because I am assuming you probably are more experienced than I am. But, as I stated earlier, I did have a customer who had two small cuts on the wires that were connected to the load side of a GFCI. The GFCI would reset with no problems. However, when a load was attached, which in this case was his treadmill, after an amount of time, the GFCI would trip. After separating these wires, and taping over the areas that were the insulation was cut, the treadmill would work just fine and would not trip the GFCI. Perhaps I made an assumption. My assumption would have been that, as more current was drawn by the motor on the treadmill, the more likely it was to leak to ground through those small cuts in the insulation. All I did to correct the problem, was to separate the two wires where the insulation had been compromised, tape over the insulation, and everything was fine after that. If my assumption is wrong, please explain that, if you will. I would like to learn something if that's what needs to happen. I guess I would also have to ask if what you stated is true then why do we do insulation testing? What does it matter if the insulation is poor or not or has a low resistance as long as the conductors are not physically touching there should be no problems. I'm definitely not asking this in a smarty pants way either; again, if I need to learn something then I want to learn it or better understand it. Thanks in advance.


I think you are trying to use what you have learnt at higher voltages and use the same rules at low voltage. On a high voltage cable even a scratch can lead to corona which can lead a to failure.

On 120 either the wires touch or you need a carrier to bridge the gap. (mold, insects, etc)

I think the big secret is that most cables are nicked when the exterior sheathing is removed. Ive watched residential guys strip and install a backstab in under a minute and move on to the next like a robot. when i asked how do you do that with out nicking the wire the guy said it takes practice and it doesn't matter if you do nick it.


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## eddy current (Feb 28, 2009)

active1 said:


> eddy current said:
> 
> 
> > When I see a receptacle that has tape wrapped around it my first thought is that it was not installed by a professional.
> ...


Tape on receptacles!!!!!


Working live !!!!!


Omg, what a hack!!! 

Lol , jk


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## paulengr (Oct 8, 2017)

gpop said:


> I think you are trying to use what you have learnt at higher voltages and use the same rules at low voltage. On a high voltage cable even a scratch can lead to corona which can lead a to failure.
> 
> On 120 either the wires touch or you need a carrier to bridge the gap. (mold, insects, etc)


Same logic applies either way. 300 V/mm is usually considered the distance at which you can "track" or "arc over". It still works even at low voltages with very thin traces on circuit boards. So for 120 V, that would work out to 0.4 millimeters or about 0.016", or about 1/64 inches. If I remember right #14 THHN is around 16 mm of insulation. So the wires don't have to touch but darned near it.


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## Paul S. (Sep 8, 2012)

I'm hesitant to send this, I definitely don't want to be seen as a hard head here. I gain a lot of valuable input from this site. Take this for what it's worth, I hope it increases, at least, my understanding of what we have been discussing. This is from Fluke's website:

Leakage current measurement basics
May 2013


In any electrical installation, some current will flow through the protective ground conductor to ground. This is usually called leakage current. Leakage current most commonly flows in the insulation surrounding conductors and in the filters protecting electronic equipment around the home or office. So what's the problem? On circuits protected by GFCIs (Ground Fault Current Interrupters), leakage current can cause unnecessary and intermittent tripping. In extreme cases, it can cause a rise in voltage on accessible conductive parts.

The causes of leakage current

Insulation has both electrical resistance and capacitance - and it conducts current through both paths. Given the high resistance of insulation, very little current should actually leak. But -- if the insulation is old or damaged, the resistance is lower and substantial current may flow. Additionally, longer conductors have a higher capacitance, causing more leakage current. That's why GFCI breaker manufacturers recommend one-way feeder length be limited to 250 feet, maximum.

Electronic equipment, meanwhile, contains filters designed to protect against voltage surges and other disruptions. These filters typically have capacitors on the input, which adds to the overall capacitance of the wiring system and the overall level of leakage current.


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## Paul S. (Sep 8, 2012)

paulengr said:


> gpop said:
> 
> 
> > I think you are trying to use what you have learnt at higher voltages and use the same rules at low voltage. On a high voltage cable even a scratch can lead to corona which can lead a to failure.
> ...


This, at least in my mind, agrees with my experience, (and the example I wrote of earlier.) However, I'm willing to admit that I might be missing something, or misunderstanding what really happened.


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## splatz (May 23, 2015)

paulengr said:


> Same logic applies either way. 300 V/mm is usually considered the distance at which you can "track" or "arc over". It still works even at low voltages with very thin traces on circuit boards. So for 120 V, that would work out to 0.4 millimeters or about 0.016", or about 1/64 inches. If I remember right #14 THHN is around 16 mm of insulation. So the wires don't have to touch but darned near it.


That's pretty damn close going from memory! 

https://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheetOEM5 

12 and 14 AWG THHN is 15 mils (0.015") insulation plus 4 mils (0.004") jacket (the clear layer over the actual insulation) and 0.019" is about half a millimeter. 

So if you made two razor nicks, and lined them right up, the conductors would be 1mm apart and no arc. 

Real world confound I'd anticipate, when you fold up the wires, that razor knick could turn into a stripped wire, it's no longer a nice straight wire with a barely there razor thin nick in it.


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## splatz (May 23, 2015)

Paul S. said:


> This is from Fluke's website: Leakage current measurement basics May 2013


Here's the full article, I learned something there, thanks for posting 

http://en-us.fluke.com/community/fluke-news-plus/clamps/leakage-current-measurement-basics.html 



Fluke said:


> Leakage current measurement basics
> May 2013
> 
> 
> ...


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## paulengr (Oct 8, 2017)

Usually I run into THHN ground faults from chafing on the end of a conduit (no bushing) or where someone just run them through an opening with a cut edge that wasn't even filed.

The clear jacket is nylon. The insulation is PVC on THHN.


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## just the cowboy (Sep 4, 2013)

*The more current part*



Paul S. said:


> This, at least in my mind, agrees with my experience, (and the example I wrote of earlier.) However, I'm willing to admit that I might be missing something, or misunderstanding what really happened.



I think it was the more current part not the jumping over part. More current will not change the arc distance. As for the tread mill example vibration was probably the cause.


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## Paul S. (Sep 8, 2012)

just the cowboy said:


> Paul S. said:
> 
> 
> > This, at least in my mind, agrees with my experience, (and the example I wrote of earlier.) However, I'm willing to admit that I might be missing something, or misunderstanding what really happened.
> ...


I suppose, it's possible that vibration from the machine could be coming up through the cord and jiggle those conductors just enough... I suppose it's also possible that as more current is drawn, you'll have a little more heat, that could change things a bit also.


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## StriickeN (Sep 11, 2017)

We run into this problem multiple times a week (the "electrician" they hire always taps into our dedicated circuits) so when rain gets into the fan it trips the breaker. Even if i stub out a wire for their fan they dont even use it... A lot of times the d/c is full of water too.


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## erod0815 (Jul 15, 2018)

How many amps is the GFCI receptacle? If the fan puts out more amps than the receptacle can handle, it will trip every time.


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## erod0815 (Jul 15, 2018)

Radon Fan Tripping


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## readydave8 (Sep 20, 2009)

erod0815 said:


> How many amps is the GFCI receptacle? If the fan puts out more amps than the receptacle can handle, it will trip every time.


should only trip on fault current, not overcurrent, right? also not familiar with a fan "putting out" amps:vs_rocking_banana:


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