Current leakage on residential service

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mattsilkwood

Senior Member
Location
missouri
wptski said:
Jim:

Right, they all flowing through the clamp but what flows some gets cancelled out and what's left is leakage. I've seen graphics where the magnetic fields are shown. Since you don't agree with the ECM article which is a carbon copy of other articles I've read on subject, you'll never change your views.
ok leakage where is it leaking to it cant just dissapear.
 

wptski

Senior Member
Location
Warren, MI
Karl Riley:

I have several clamp meters and probes but don't have every current clamp made but I've never seen one that has a "zero" button for AC current, only DC current. What make/model are you using?

If you or others would like to see this thread end, stop posting the same "Is there a problem causing concern" or "What's your electrical problem", etc.

Posting about the low current leakage in this forum was a big mistake as this forum would only be cocerned if it's at a dangerous level. It's more at a electronic level than electrical.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Bill,
Your stuck on zero! Look at Post #10, the link to a Fluke PDF on current leakage. Look at Fig. 1, does it say that it's going to read zero? Why do it if it's going to read zero, right? If you get a reading, it's leakage.
To have leakage there has to be a path for the current to flow on...detectable amounts of current don't flow through the air on 120 volt circuits. All of my posts say that if there is no other current path other than the cord then the meter has to read zero or it is wrong. There is nothing that will change this law of physics.
Don
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Bill,
Current flows over and through the insulation. Insulation is just another path.
And this path is within the amp clamp...why doesn't the meter see it? Does it make a different type of magnetic field that the meter doesn't detect?
Don
 

76nemo

Senior Member
Location
Ogdensburg, NY
wptski said:
Brian:

Your profile states that you are a contractor. You have 7/8 current clamp meter that you don't trust below 1A!:-? Reading a branch circuit, my AEMC 565, F25 and MeterMan CT238 probe all show around .4A.

I'm not sure if there's a way test a RMS meter for zero as they are going to flicker a bit on the last digit with nothing clamped.


Brian, are you a construction contractor? I know WPTSKI from another forum, and he mentioned this post. Do you ever have to troubleshoot any old institutions or refurbished office space?

Check out Fluke's 360 and it applications in fluke.com. What WPTSKI is speaking of is a totally different application than what you're thinking, it seems. Fluke's 360 holds a hefty price tag, but look at it's spec's and you'll appreciate why!
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
76NEMO and Bill,

I have not read any post that says low level leakage current does not exist.

What I have seen are repeated requests for Bill to identify the specific leakage current path he discussed concerning his corded appliances.
And I have not heard from Bill why his meter does not effectively read zero if his clamp on encompasses ALL current paths.

What specifically don't you like about this discussion? Do you want to discuss possible health concerns? How about EMI issues? Or is it insulation degradation?

It seems you are interested in advancing the general use of a clamp-on meter (not manufacturer specific) to find situations of low level of leakage current.

Oh by the way, I did not say I did not agree with the EC&M artical, I only said I did not agree with the definitions.
 

wptski

Senior Member
Location
Warren, MI
Jim:

The path is through the insulation to ground that's what leakage is. My meter won't read zero in ma range because it can only go to .01ma but why, again to you say zero? If I put it in the higher amps range, it'll read zero then! Take a look at the link in Post #10, Fig #1 where the clamp is around a single phase and grounded conductor. Why are they showing that? Why would they show that if it's always going to be zero??? They are showing you how to use the clamp to read leakage current. In a perfect world, it would read zero but no insulation is perfect and there is always some leakage.

Is the leakage I seen a problem? No! I got interested in general power quality issues and wanted to look at leakage current. I'm not try to promote anything at all.
 

karl riley

Senior Member
Bill, my clamp-on with a zero button is an Extech 380947. I also use a Soar 611. The Extech actually has a resolution of 1 mA.

Bill, I have to ask you at this point to say specifically what you want to find out. Forget all the previous posts. Dereck has answered you in relation to micro-amps. I have given you my guess as to the current on the grounding conductor you originally asked about.

If you can say what you want to find out perhaps the other posters can try to stick specifically to that question.

Karl
 

wptski

Senior Member
Location
Warren, MI
Karl:

I have a Extech 380942, I think that's model number anyway, not with me right now. It has a zero button but has no function in AC amps just DC amps. The same with a Fluke i1010, Meterman CT238 and ESI695(???). The CT238 has a zero adjust, not a press to zero. Some function as zero or relevant in DC volts. I don't think there is a zero button on the Fluke 360 either! It's the AC/DC clamps that normally have that and that's why I asked.

I was looking for trouble. It's a preventative maintainance thing. Like going to a doctor for a check up, hoping not to find a problem but if you do, fix it. Seems like you guys can't understand that! Unless it blows a fuses, trips a breaker or your getting poked, you have no problem.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Bill,
Why would they show that if it's always going to be zero??? They are showing you how to use the clamp to read leakage current.
It is not always going to read zero, but the in the case you have defined, there is no other current paths for the leakage to flow on so it must read zero or be in error. Checking for leakage is a common test, but in many cases there are multiple remote paths for the current to flow on...you example has no such path.
The path is through the insulation to ground that's what leakage is.
There has to be a conductive path for it to get to ground. With the cord connected isolated appliance, where is this conductive path? It doesn't just flow through the air at this voltage.
I was looking for trouble. It's a preventative maintainance thing. Like going to a doctor for a check up, hoping not to find a problem but if you do, fix it. Seems like you guys can't understand that!
I think that most of us understand that, but the choice to do that type of testing is not ours to make...it is an economic decision made by the client. Some will have PM testing done on a regular basis and others only react to problems.
Don
 

wptski

Senior Member
Location
Warren, MI
Karl:

I can't view a PDF(Manual) from where I'm at right now but the specs listed at Tequipmet state the Auto One-Touch Button which also serves as a relevant too for DCA only. Unless the manual contradicts this, zero serves no function in AC amps.
 

wptski

Senior Member
Location
Warren, MI
Don:

I know what you are saying! If it's a two wire power with no grounding, there's no place or ground for the current from leaky insulation to go to, right? If so, a two wire cord will never leak current, right? Then why has Fluke shown us how to use their current leakage clamp around a single phase wire and a grounded conductor? Are they wrong?

I've seen some place a explantion of this with graphics but don't remember where! Would you believe it anyway???
 

plate

Senior Member
Location
South East PA
On the issue of zero current: The current transformer on a hand held meters such as these (and others) have a resistor on their ?terminals.? The meter is a voltage meter, with ac signals and the meter set to measure its lowest possible value, you may never read ?zero,? it depends on how they set up the meter.

If you take some of the best CT?s made (like a pearson) and hook it up to a very high quality data acquisition system, there is always going to be some low level amount of noise, the voltage you measure (equivalent current) will never be zero.

I believe when someone states zero, I believe they are saying that it is essentially zero, or not measurable using that particular meter or system.
 

dereckbc

Moderator
Staff member
Location
Plano, TX
wptski said:
I was looking for trouble. It's a preventative maintainance thing. Like going to a doctor for a check up, hoping not to find a problem but if you do, fix it. Seems like you guys can't understand that! Unless it blows a fuses, trips a breaker or your getting poked, you have no problem.

That is a very condescending tone, and shows a lack of respect and knowledge of what we do. That is the reason for a lot of the negative feedback you are receiving.

For example: my job title is a Power Protection Engineer for a very large telephone company, In all our telephone switching offices I install current detection systems on all DC and AC distribution system to monitor for any current on the grounding and bonding systems. When it detects current; it sets off a loud alarm bell then sends telemetry to a central alarm monitoring point for follow up investigation. In just about every case the result is from installation activities from technicians and installers making improper wiring terminations on the power systems

Electricians do look for current on equipment grounding conductors and grounding systems; Karl makes a living at it and written books about the techniques. What every electrician on this board will tell you is when they find current on the system, the vast majority is from improper wiring techniques that do not comply to NEC, like bonding the grounded circuit conductor (neutral) downstream from the service disconnect device. In the rare cases where it is the equipment, all the electrician has the authority to do is notify the owner to have the equipment repaired and/or replaced. Sometimes the electricians even find bootleg grounds, especially in IT systems where some technician went in and bonded the neutral to ground together in a receptacle or panel to eliminate a voltage difference between N-G.
 

karl riley

Senior Member
Bill, I will address the one question you asked, which was why would Fluke show a clamp-on being used clamped around a hot and a neutral (ungrounded and grounded conductors) if it was always going to read zero?

This is what I do all the time when I am called in to trace the source of net current magnetic fields in circuits. If you clamp around a hot and neutral and get a reading (usually a half an amp to many amps) that means one of two things, usually:

1) Some of the neutral that should be balancing out the hot is traveling in another path, either a separate grounding path, or to another neutral. This would indicate a wiring error that needs to be corrected.

2) There is excess neutral, coming from another circuit. This also would be an error.

The follow-up measurements would be to measure the hot and neutral separately to see what the situation is. This is often done in the panel box.

Since we are not dealing with micro-amps we don't have to be worried about the absolute accuracy of our ammeters. We are seeing symptoms which lead us to the cause of the disease.

If it is said that the conductors you are measuring are going to a completely isolated appliance, and there is no equipment grounding conductor, then the reading should be zero. If it is not, either the meter is at fault or the appliance actually is not isolated and you need to investigate further.

Bill, I would suggest that if you have any more to say about instruments, you should start a new thread purely about instruments and their accuracy and tolerances.

This thread may have run itself out, but if you have anything more to say about the cause of net currents, let's hear it. I believe you have been told that any parallel currents flowing on insulation would not show up as net current.

Karl
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Bill,
I know what you are saying! If it's a two wire power with no grounding, there's no place or ground for the current from leaky insulation to go to, right? If so, a two wire cord will never leak current, right? Then why has Fluke shown us how to use their current leakage clamp around a single phase wire and a grounded conductor? Are they wrong?
That is not what I have been saying....in many cases there are other current paths and there can be significant amounts of leakage current. That would be what the Fluke document is talking about. Your example was an isolated appliance with no current paths that can flow measurable current other than the cord. If there are no paths other then the cord, your meter should always sum to zero...it is only when there is an external path with a low enough impedance to permit a measurable amout of current to flow that you will read other than zero. Many installations have multiple other paths, but you said your appliacne is isolated. The only way to know is to meg all of the coundutors of your test appliance to the electrical system grounding conductor while the appliance is not connected to the electrical system. Take the results of that test and apply ohms law to find the maximum possible leakage current.
I've seen some place a explantion of this with graphics but don't remember where! Would you believe it anyway???
If it shows current flow without a path, then no I woundn't beleive it because it would be wrong.
Don
 
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wptski

Senior Member
Location
Warren, MI
Karl:

For one, to refer to it as net current from what I've read, you need clamp around the phase, ground conductor and grounding wire too.

Excess neutral! Explain that please.

You did point out one that I wasn't going mention fearing stirring the pot anymore. Using two probes of the same make/model. Matched? Of course not! Clamped one on the phase andthe other on the grounded conductor on a inductive load, connected to a scope, looking at phase angle. They are shy a degree or two of cancelling eachother out. Do the same on a pure resistive load and it's more like zero phase angle.

If you found .5A of leakage, what prompted the call?

What wrong about talking meters? Is was the first thing brought up. That I couldn't measure microamps. I would never start a new thread here or post in another thread after this one. I learn from my mistakes!

I'd like to know about the zero button on your Extech, does it really zero in AC current or DC only?

Do you know that you can read leakage of one type around phase and grounded conductor without a load?

This thread will stop when you want it to by not replying.
 

brian john

Senior Member
Location
Leesburg, VA
Brian, are you a construction contractor? I know WPTSKI from another forum, and he mentioned this post. Do you ever have to troubleshoot any old institutions or refurbished office space?

I am not a construction contractor (not that makes a difference) I am an electrician that specializes in solving problems other electrical contractors, facility personnel, or engineering firms can't. I have never NOT solved a problem in 23 years in business and another 14 working for others (well maybe as an apprentice). I am not SMART by any means but I am diligent. I have worked in just about any type of facility, you can name.

Above that I own an electrical contracting firm that in addition to service and small installations performs electrical testing, Infrared scanning and maintenance on generators, battery systems, most electrical distribution equipment.

My question to Bill was and remains WHAT IS HIS QUESTION or issue, and from the post of others it seems they are in the dark also. I think it is great he posted here, I am all for open discussion, not overly impressed with his attitude, it sure got under my skin.

For me leakage current as noted previously, is not an issue when it is proven to be a by product of a properly installed and tested system.
 

wptski

Senior Member
Location
Warren, MI
Don:

I've checked a few appliances but lets take one, a gas dryer. It has a three pronged power cord, so it has one path to ground. Another path that somebody pointed out above, the gas line itself. Where shall I start? I have a Fluke 1507 insulation tester, no megger.
 
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