Current leakage on residential service

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don_resqcapt19 said:
Bill,

No matter what the resistance is, the current will follow ohms law. It would not be unusual to get a megger reading of over 100 meg for an appliance. A 100 meg would result in a leakage current of 1.2 micro amps. Your meter has a resolution of 10 times that with a plus or minus 5 count accuracy. I guess the only way to continue is if we know the resistance of all of the possible leakage paths.
Don
Don:

We're making gains, as we've got away from the zero current statement. A couple of posts above I said that the 565 won't read lower than .01ma. Even with those specs, that isn't much current flow. Would you consider current flow below .01ma a problem? What would you consider a problem?
 
Bill,
I don't see the flow as a problem...the only problem I see is the meter reading current if there isn't any. I'm not sure we are away from the zero statement. If the expected current based on a megger reading is 1/10 of the resolution of the meter, then I think it should read zero.
Don
 
don_resqcapt19 said:
Bill,
I don't see the flow as a problem...the only problem I see is the meter reading current if there isn't any. I'm not sure we are away from the zero statement. If the expected current based on a megger reading is 1/10 of the resolution of the meter, then I think it should read zero.
Don
Don:

The ECM article says or at least I gather from it that there will always be "some" current flow or leakage through the insulation.

As far as the meter goes, I don't know how it works or should at currents at or below .01ma. A Fluke 360 has a low 3ma range setting but I didn't want to pop for that in the first place!
 
Last edited:
Leakage is there, yes. I guess my point in all this is where are you going or what do you want to know or do. Does leakage current exist, yes.

At what point does it become a problem? We have had buildings where the ground current measured in excess of 300 amps. We isolated and found the neutral/grounded conductor in a 4000 amp busway was grounded. THIS WAS A PROBLEM, but they had lived with it for years, it was not till they added load and the current exceeded the 320 amp setting on the GFP relay and tripped the building did it become an noticcable issue.

Other places we have had low amperage readings 1-5 amps but it was causing screen shake. We isolated and repaired this also.

But in every building we measure some ground current, there is some measurable reading typically in the 1-5 amp range. The question for me at this point is is this leakage or due to a downstream ground.

I think (IMO), if the feeders, branch circuits and distribution equipment are meggered and meet acceptable industry standards, anything you measure that would be considered leakage current, that is, not due to intentional or accidental neutral to ground connections downstream from the main service, is accceptble.





(take a look at NETA Interantional Testing Association specs)
 
Bill,
The ECM article says or at least I gather from it that there will always be "some" current flow or leakage through the insulation.
True as there is no such thing as a perfect insulator, but in most cases this current will not be measurable.
Don
 
As far as a clamp on meter being capable of measuring currents in the 1 mA range, I admit that I was also very skeptical as some have already mentioned. However, I have used a fluke multi-meter (187) and a clamp on AEMC (model 759, I believe) and it seemed to be adequate in the single digit mA range. I must say however, that I was not impressed with the AEMC tech people.

One of these days, I will verify a few values using some Pearson Electronics Inc CT?s connected to a good data acquisition system that we have.

As far as what leakage values are to be concerned about, I will leave that to others. But perhaps the interest in this subject could also come from an article in ECM magazine a few months ago in which they talked about current flowing into one home from another via a metal cold water pipe due to a poor service neutral connection at the other home.

A paragraph in that article mentioned a possible link to childhood leukemia. It involved low amounts of current flowing through a child when the child touched the faucet (cold water line) and a drain in the tube (at a different potential). I have no opinion as to likelihood of this medical issue.
 
brian john said:
Leakage is there, yes. I guess my point in all this is where are you going or what do you want to know or do. Does leakage current exist, yes.

At what point does it become a problem? We have had buildings where the ground current measured in excess of 300 amps. We isolated and found the neutral/grounded conductor in a 4000 amp busway was grounded. THIS WAS A PROBLEM, but they had lived with it for years, it was not till they added load and the current exceeded the 320 amp setting on the GFP relay and tripped the building did it become an noticcable issue.

Other places we have had low amperage readings 1-5 amps but it was causing screen shake. We isolated and repaired this also.

But in every building we measure some ground current, there is some measurable reading typically in the 1-5 amp range. The question for me at this point is is this leakage or due to a downstream ground.

I think (IMO), if the feeders, branch circuits and distribution equipment are meggered and meet acceptable industry standards, anything you measure that would be considered leakage current, that is, not due to intentional or accidental neutral to ground connections downstream from the main service, is accceptble.





(take a look at NETA Interantional Testing Association specs)
Brian:

My original question was about "normal" current in the neutral at the POCO which was answered way above. I mentioned the small current reading in a power cord and it kind-of took off! I was curious about leakage current, etc., so I looked into it. Just poking around.

At 300A, you don't even need a special current leakage meter. I can see your point. No megger here but I have a Fluke 1507 insulation tester.

Thanks for your input!
 
plate said:
As far as a clamp on meter being capable of measuring currents in the 1 mA range, I admit that I was also very skeptical as some have already mentioned. However, I have used a fluke multi-meter (187) and a clamp on AEMC (model 759, I believe) and it seemed to be adequate in the single digit mA range. I must say however, that I was not impressed with the AEMC tech people.

One of these days, I will verify a few values using some Pearson Electronics Inc CT?s connected to a good data acquisition system that we have.

As far as what leakage values are to be concerned about, I will leave that to others. But perhaps the interest in this subject could also come from an article in ECM magazine a few months ago in which they talked about current flowing into one home from another via a metal cold water pipe due to a poor service neutral connection at the other home.

A paragraph in that article mentioned a possible link to childhood leukemia. It involved low amounts of current flowing through a child when the child touched the faucet (cold water line) and a drain in the tube (at a different potential). I have no opinion as to likelihood of this medical issue.
I have a Fluke 189 which is said to be out of production and be replaced by a new model!! I haven't dealt with AEMC tech support too much other than trying to help interpeting their terrible manuals.

They did relay that a cutomer had current in effluent going through pvc in a dairy. Now that's a load, hey?:grin:
 
don_resqcapt19 said:
Bill,

True as there is no such thing as a perfect insulator, but in most cases this current will not be measurable.
Don
Don:

They have some pretty strict specs for leakage for medical equipment. They say that 1ma can be felt.
 
wptski said:
Don:

They have some pretty strict specs for leakage for medical equipment. They say that 1ma can be felt.

And this is handled by keeping the conductors short.

The iso system alarm threshold is 5ma or 24,000 ohms of total impeadance, but the system must have a minimum of 200,000 ohms, or no more than .0006 amps of total leakage current in an idle state (no load) with all breakers on and the LIM connected.

Insulation must be XHHW.

The test sets for these systems are pretty high tech units, cheaper test sets used to be in the $7,000.00 range and must be calibrated yearly.

I have no idea what they run now.

Roger
 
I do not know if anyone has brought this up or not. I got bored reading all the pages of debate. Here is some food for thought.

Any electrical system has distributed capacitance between all the circuit conductors. The larger the system, the more capacitance there is. Just about all of the equipment will have some form of RFI devices (in the form of capacitors) and possible MOV's installed from L-G and N-G. This is the source of current.

With distributed line capacitance, filters and MOV's is the source for unexplained currents in the Equipment Grounding Conductors in what is known to be a properly wired and functioning system.

It can be of several amps in large industrial system, or low micro-amp region of residence. To many varibles to predict, but if all you are worried about is a few milli-amps, life is short and there are better things to do than chase ghost.
 
dereckbc said:
I do not know if anyone has brought this up or not. I got bored reading all the pages of debate. Here is some food for thought.

Any electrical system has distributed capacitance between all the circuit conductors. The larger the system, the more capacitance there is. Just about all of the equipment will have some form of RFI devices (in the form of capacitors) and possible MOV's installed from L-G and N-G. This is the source of current.

With distributed line capacitance, filters and MOV's is the source for unexplained currents in the Equipment Grounding Conductors in what is known to be a properly wired and functioning system.

It can be of several amps in large industrial system, or low micro-amp region of residence. To many varibles to predict, but if all you are worried about is a few milli-amps, life is short and there are better things to do than chase ghost.
Try searching for IEC-601 or UL-544, that'll get you started if you think that it's nothing.
 
Bill,
They have some pretty strict specs for leakage for medical equipment. They say that 1ma can be felt.
That is a lot bigger number than what I am talking about. If I meg the equipment and have a 100meg(100,000,000)ohm leakage path and the voltage is 120 volts the current is 0.0000012 amps that is a lot less than 1mA (0.001 amp). Often my megger says that the leakage path is greater than 1999meg.
Don
 
WPTSKI, I thought you were talking about your home for things like a washing machine, lathe, and humidifier. Is that correct?

That has nothing to do with med equipment and surgical rooms. Leakage current is a concern in patient areas because small amounts of leakage current can develop small voltage potential differences. The only reason that is important in medical areas is because when you are under anesthesia, have open wounds, or otherwise sick the bodies electrical resistance is extremely low and the lower voltages can push lethal current through the body. Secondly voltage difference might cause a spark in areas where surgical gasses are use.

I have read through many of the post here, and familiar with many of the responders which represent hundreds of years of experience including my 30 + years specializing in grounding, TVSS, DC and particularly leakage current associated with power quality. The amounts of currents you are seeing is normal and there is no fix assuming the devices are operating properly.

Roger who has responded specializes in Hospital design and I am certain he will concur even in hospitals there is leakage current on the overall electrical systems, it is just limited in certain areas and eliminated to the extent possible on medical equipment used in surgery where there are gasses and patients.
 
dereckbc said:
Roger who has responded specializes in Hospital design and I am certain he will concur even in hospitals there is leakage current on the overall electrical systems, it is just limited in certain areas and eliminated to the extent possible on medical equipment used in surgery where there are gasses and patients.

Dereck, absolutely, and as Don mentioned earlier, there is no perfect insulator, and the dielectric strength of even the best conductors have a limit.

Wptski, BTW, I think Dereck is probably aware of the documents / standards you referred to.

I don't really understand what your worries are with the values you are seeing in a residential setting, even if they are real and not meter error.

If there were 5ma (I haven't read every post, but I saw that scanning the thread) we would be at or approaching a GFCI trip level, anything lower should not be a major concern. Just MHO.

Roger
 
dereckbc said:
WPTSKI, I thought you were talking about your home for things like a washing machine, lathe, and humidifier. Is that correct?

That has nothing to do with med equipment and surgical rooms. Leakage current is a concern in patient areas because small amounts of leakage current can develop small voltage potential differences. The only reason that is important in medical areas is because when you are under anesthesia, have open wounds, or otherwise sick the bodies electrical resistance is extremely low and the lower voltages can push lethal current through the body. Secondly voltage difference might cause a spark in areas where surgical gasses are use.

I have read through many of the post here, and familiar with many of the responders which represent hundreds of years of experience including my 30 + years specializing in grounding, TVSS, DC and particularly leakage current associated with power quality. The amounts of currents you are seeing is normal and there is no fix assuming the devices are operating properly.

Roger who has responded specializes in Hospital design and I am certain he will concur even in hospitals there is leakage current on the overall electrical systems, it is just limited in certain areas and eliminated to the extent possible on medical equipment used in surgery where there are gasses and patients.
You said that you were bored with thread, chasing ghosts, et. like leakage means nothing but there are cases were it does, medical equipment!

I never said that what I'm reading for leakage is dangerous. I was told that I was mistaken, no clamp meter will read that low and the current will be zero. All three points have been reversed.

My mistake was mentioning this low leakage current as it seems to have caused a uproar here!

Yes, I "mainly" refering to residential types of appliances and some light machinery!

This is the second time that "years of experience" is mentioned. Is there something wrong with questioning an answer here? I have 34 years in my trade and never had a problem with a apprentice questioning an answer I gave or something I did!
 
roger said:
Dereck, absolutely, and as Don mentioned earlier, there is no perfect insulator, and the dielectric strength of even the best conductors have a limit.

Wptski, BTW, I think Dereck is probably aware of the documents / standards you referred to.

I don't really understand what your worries are with the values you are seeing in a residential setting, even if they are real and not meter error.

If there were 5ma (I haven't read every post, but I saw that scanning the thread) we would be at or approaching a GFCI trip level, anything lower should not be a major concern. Just MHO.

Roger
Roger:

Never said that I was worried about the current leakage I was seeing. I have no idea what you all do for a living or what your expertise is!

AhHa! GFCI values are exactly what I asked of in another forum, if those values could be used as limits of safety!

Seems like there were users that were better suited to address the low leakage current point but weren't here or didn't post.
 
I was told that I was mistaken, no clamp meter will read that low and the current will be zero.
That is still my postition with equipment that has what I find to be typical megger readings...that is in excess of 100meg. Sure there may be lab instruments that can read this very low current, but not something you can buy.
Don
 
wptski said:
I was told that I was mistaken, no clamp meter will read that low and the current will be zero. All three points have been reversed.

I said your meter could not read microAmps. I was partially wrong, your meter specs say it cannot read less than 10 microAmps.

I said the meter will read zero (in your case that is still .01mA) if you clamp it around all of the current paths. This is a basic law of physics and must always be true.

This is the second time that "years of experience" is mentioned. Is there something wrong with questioning an answer here? I have 34 years in my trade and never had a problem with a apprentice questioning an answer I gave or something I did!

So far we have 59 discussions over 6 pages, that is a lot of questions and answers. The problem seems to be you are not getting an answer that you like.

Yes, leakage current is real. Yes, it is measurable. Yes, it can be dangerous. However, your meter shows there is leakage current from a 3 conductor cord connected appliance insulated (maybe even isolated) from ground but you have yet to identify the path that current is taking.
 
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