Current on Conduit

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Old 04-16-14, 10:18 AM
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Current on Conduit

I put a clamp on ammeter on a piece of 1/2 emt while that circuit was under load and I was getting almost 1 volt of current.... I don't think I am able to test a pipe for current like this (ie clamp meter is for one conductor) however, does that mean I have voltage leaking to ground?
 
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Old 04-16-14, 10:25 AM
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Normally the current going out on wires inside the conduit equals the current coming back on (neutral) wires inside the same conduit so you should read zero amperes using a clamp on ammeter. But within the conduit one wire is likely more centered between the ammeter jaws compared with another wire and the net current as measured would then end up unbalanced (nonzero).

A clamp on ammeter is intended to measure current in one conductor at a time.

By the way, if you set the clamp on ammeter (if it is a multimeter) to volts, any clamp on readings are meaningless. You need to use the two wires with clips or probes for voltage measurements.
 

Last edited by AllanJ; 04-16-14 at 11:19 AM.
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Old 04-16-14, 11:28 AM
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This is a 240 circuit, however there is a neutral.

So how would one tell if there was any voltage on a conduit, obviously not enough to trip a breaker?

EDIT-- Ive been going around the house with my clamp meter and I am getting current on many of the conduits in my basement. All less than 1 volt AC.

Is that false reading? Whats happening here?
 

Last edited by ardmi; 04-16-14 at 02:07 PM.
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Old 04-16-14, 03:20 PM
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It gets weirder... after a few hours the same conduits that were showing less than 1 current on them, all now say 0. Nothing has changed in the house.

When they were showing current, turning off those circuits in the panel had no effect... they were still showing some amperage,

Now I turn on my dryer circuit and after a few minutes the slight amperage returns on all the conduits that were showing current before.....

And then I check my GEC at both the ground rod and the water main and when those other pipes are showing current... the gec always read 0?

does it sound like I have an issue here?
 

Last edited by ardmi; 04-16-14 at 04:44 PM.
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Old 04-16-14, 03:33 PM
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No you don't have any issues. Rest easy.
 
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Old 04-16-14, 04:04 PM
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Please elaborate Chandler.
 
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Old 04-16-14, 04:08 PM
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A clamp on ammeter can't read voltage with the clamp. Are you referring to amps?
 
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Old 04-16-14, 04:10 PM
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Are you just playing with the ammeter? I don't understand the concern of the reading since,it has been explained pretty well. You are getting an uneven return reading, which should be zero, but can vary due to the location of the individual wires in the conduit. The GEC will, or should read zero. The neutral will read the same as the hot wire, but reflected. So if clamped together the reading is zero. Too much time involved in an area of small concern. It poses no problem.
 
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Old 04-16-14, 04:34 PM
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Like I said, its reading current... or amps. less than 1 amp on some of the conduits at transient times... it fluctuates at time 0 other time other readings. I can also turn off the circuit and still get a reading on that conduit...

Alans response is great, but I am still confused why I am getting AMPERAGE on my conduit and that it FLUCTUATES....

I assume my clamp meter is measuring the flow on the conduit and not the wires inside.
 
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Old 04-16-14, 05:04 PM
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I also just clamped the water pipe as it enters my basement before the meter and I am getting .30 amps on it. However, the GEC connected to it is showing 0.

Im getting real nervous here....
 
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Old 04-16-14, 06:07 PM
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It is a digital meter isn't it? Read:http://www.doityourself.com/forum/el...m-voltage.html
 
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Old 04-17-14, 04:53 AM
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I think dismissing it for phantom voltage is a cheap way out. Surely there is some explanation why I am reading less than an amp on my water ground and on the same on some of the conduits. Phantom voltage would suggest it would be constant as I have seen it fluctuate from 0 to 1 amp over time. And switching off the circuits that are inside the conduits that are showing a reading has no effect, it doesn't disappear.
 
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Old 04-17-14, 05:01 AM
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Induced voltages from other circuits can be affecting your readings. You are obsessed with a trivial matter that ties up a great deal of time to explain. For one, and with no disrespect to you, I will leave this thread to others who care to banter about it.
 
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Old 04-17-14, 05:22 AM
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That's the second time you dismissed my question Chandler. My concern is definitely valid even if you are unable or unwilling to answer it properly.

I fear there is a neutral issue at play here.

For example, I am getting current on my GEC at the water entrance. Its low, about .50 Amps. When I turn on a microwave up stairs, the GEC jumps to .75 amps. The microwave on the other circuit is also making a small difference in the reading on the conduits.
 
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Old 04-17-14, 07:34 AM
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I narrowed down the current on the conduit to a specific circuit.

When a refrigerator was running, I am getting the amp reading (about a .5 to 1.5A) on the conduit the circuit is run in. I am also getting some current, but to a lesser reading, on a nearby conduit on a different circuit.

When the refrigerator is turned off the current readings go to "0" on both conduits....

Now I am trying to make sense of this. It seems I am barking up the wrong tree here probably.
 
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Old 04-17-14, 07:39 AM
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Can you explain how you are measuring the current on the conduit? Are you just putting a clamp on meter around it?
 
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Old 04-17-14, 07:48 AM
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I don't really know how clamp on ammeters work but I am led to believe that the conduit is too fat to be measured let alone the individual current carrying conductors inside influencing the meter reading.

If you get a reading of more than a tenth of an ampere when clamping a grounding electrode conductor (usually less than 1/4 inch wire from ground rod or water pipe to panel) then you should check your ground and neutral wiring.
 
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Old 04-17-14, 08:07 AM
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Its not the fridge, its the circuit. a 1500 heatgun puts about 5 amps on the conduit. But I am not sure if that means I am reading current flow on the conduit or non-zero flow from the conductors inside.

Can you explain how you are measuring the current on the conduit? Are you just putting a clamp on meter around it?
Clamping around the entire pipe. That's why I am not sure if that's an accurate measure or am I actually seeing current leaking to ground? Or something totally different.
 
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Old 04-17-14, 08:13 AM
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This video gives you the basic instruction: https://www.youtube.com/watch?v=9T4DF4JFKH8 Some of the things, and terminology he uses is not quite right but the use of the meter is correct.

Bottom line is you do not use a clamp on meter around a conduit, or more than one wire. This will either give you false readings, or just not work at all. In your case they are false readings and are of no use.
 
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Old 04-17-14, 08:23 AM
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Have you measured voltage to a known good ground using an analog multimeter.
 
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Old 04-17-14, 08:38 AM
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thanks for dumbing it down with the youtube video but A few things I read online about EMI and induced current from unbalanced raceways suggest you use an amprobe around the entire raceway just as I describe. And at that point it is measuring the conduit as a single conductor not the wires inside.

If they are false readings as you suggest, then why do they go away when the circuit is open and change under load?

And Ray I am not talking about voltage here.... im talking about amperage.


Heres one page that mentions the use of the amprobe as I describe>
Electrical Wiring Problems & High EMF
 
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Old 04-17-14, 08:56 AM
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And Ray I am not talking about voltage here.... im talking about amperage.
And I know that but without voltage to ground it is not a hazard. You may have "water" in the "pipe" but no pressure to push it out.
 
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Old 04-17-14, 09:00 AM
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Ray mentions it...because you can't have current w/o voltage...but you can have voltage w/o current.

If there is no voltage reading to ground then the current you are seeing is a false reading or is some product of the wires in the conduit. Either way, w/o a voltage to ground...it matters not. At least not as some sort of shock hazard.

The link you posted about EMF gives some good info on what may cause these imbalanced circuits, but the only way you may find it is to inspect each switch, receptacle, junction box, panel or sub-panel as well as any connected fixtures for proper wiring. The readings you are getting could be because a neutral or ground is wired wrong somewhere so that you are getting current flow on that single conductor in the conduit, but not on the hots inside. Then clamping around the conduit would be reading just that one wires current flow.

Notice the first line of the second paragraph "Since these wiring problems usually manifest no overt functional deficits in the electrical system...".

If you want to try to eliminate it, looks like you'll be doing a lot of crawling around checking every connection and making schematics of your house.
 
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Old 04-17-14, 09:41 AM
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So if I am not getting voltage on those same conduits showing current then its nothing to worry about? For example if I test for voltage between the conduits that are showing current and the ground slot on an outlet on a different circuit I am not showing voltage, just continuity.

So if I am running a high heat load (ie heat gun) that only is two prongs then its not even connected to the gec ie the conduit... so when I am seeing 5 amps when clamped around that pipe your saying I am reading the conductor inside not the conduit?

If there is no voltage reading to ground then the current you are seeing is a false reading or is some product of the wires in the conduit. Either way, w/o a voltage to ground...it matters not. At least not as some sort of shock hazard.
Then I rule out a shock hazard, what about inductive heating ie fire hazard?
 

Last edited by ardmi; 04-17-14 at 10:03 AM.
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Old 04-17-14, 10:04 AM
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That's exactly my take on it. It may be an installation issue or there could be a bad/miswired neutral on another circuit and so it is taking the path through the neutral in that conduit. Your meter would show current flow, but it's not actually on the conduit, but the single conductor inside.

I guess it could also be that the neutral in the conduit is bad/miswired..so what you are reading is the hot wire and the neutral somewhere else is returning current to the panel.

If you aren't getting voltage to ground...then there is no shock hazard. You could rig a piece of wire direct from your ground rod and use that as your ground reference, but if the conduit and water pipes are bonded together and to the ground rod...then they are all at the same potential anyway.

Finding whats causing the issue you see is going to be a ton of work as I stated. You'll have to open every single box in the house (including any that may be buried in insulation or illegally hidden), every fixture, every sub and main panel. You'll have to disconnect any hard wired items like dishwasher, water heater, garbage grinder, etc. You may have to disconnect everything, including in the panels and check continuity on every single wire from point A to point B.

Not an electrician, but I spent over 20 years in the Navy dealing with electronics and electrical systems.

Your system is working, no electrical shocks, no breakers tripping, no overheating (that you've stated anyway)...so why drive yourself crazy about what's basically a non-issue.

I am curious about 2 things...why does your IP show you in the midwest and what prompted you to even check your conduit for current flow?
 
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Old 04-17-14, 10:08 AM
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Inductive heating??? Seriously? Explain to me how that would even happen? You mean 5-10-15 amps of current on a conductor inside EMT is supposed to inductively heat the conduit enough to cause wood to burst into flame? Never happen, no way, no how.
 
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Old 04-17-14, 10:29 AM
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I would like to point that the site you linked to is a company that provides a service for a fee. I would take anything they have on there with a grain of salt unless you can find an independent site to back up their claims.

There is imbalance on all sorts of circuits in electrical installations. As you saw in the video, he was reading the loads on a three phase panel. Each leg has the same voltage, but a different amount of current. Then when you check the neutral, it was only carrying 12 amps. This can happen on any multi-wire circuit.

Is there a multi-wire circuit in that conduit? I bet there is more than two wires in it.

what about inductive heating ie fire hazard?
Does the conduit feel hot? The only time you can get a dangerous level of induced current is if somebody runs a single wire through a metal conduit, which is a code violation.
 
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Old 04-17-14, 10:34 AM
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Is there a multi-wire circuit in that conduit? I bet there is more than two wires in it.
Yes there are at least 5 or 6 conductors from two or three different circuits in that conduit. However, its turning off only one of those circuits that makes the current readings disappear.

I believe there are some switch legs in the same conduit (thinking they wouldn't have returns).

In fact you mention MWBC, there used to be surely one in that pipe. When I got a new panel installed, the electricians said they ran a separate neutral and split the shared circuit.. I hope they didn't monkey that one up (not to confuse matters, thought I would throw that out there).

Does the conduit feel hot? The only time you can get a dangerous level of induced current is if somebody runs a single wire through a metal conduit, which is a code violation.
The one showing the most current is not warm nor hot. However, a dryer circuit close by warms up pretty nice under load which I figured was normal for a 30A elec dryer circuit. That conduit shows the current as well from the other circuit... its directly next to it.


I am curious about 2 things...why does your IP show you in the midwest and what prompted you to even check your conduit for current flow?
I am in Chicago. Not sure why it says Cal. Anyway, I was checking conduit flow because of the dryer circuit I mentioned above. (however, the dryer circuit is not the one I am turning off to make the current disappear on either pipe) This can get crazy confusing quickly!
 
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Old 04-17-14, 11:03 AM
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It is normal for a pipe to get warm when a lot of current is flowing through the wires. A dryer pulls about 22 amps during normal operation.

Just for piece of mind, I would track down the "extra" neutral they installed and make sure it is properly installed.

All in all, I think this is nothing to worry about and is a case of a little knowledge being dangerous.
 
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Old 04-17-14, 11:11 AM
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All in all, I think this is nothing to worry about and is a case of a little knowledge being dangerous.
I totally agree with this. It doesn't change the fact something seems screwy.

Just for piece of mind, I would track down the "extra" neutral they installed and make sure it is properly installed.
Im guess they pulled a neutral to the box where the thought the two circuits shared a neutral. If they were in the wrong box or something... what would occur if that shared neutral is still shared downstream but now has 2 returns back to the busbar.... The two circuits are still on opposite phases.

does that make any sense... probably not.
 
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Old 04-17-14, 11:32 AM
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what would occur if that shared neutral is still shared downstream but now has 2 returns back to the busbar
Those two neutrals would just be paralleled. Not necessarily a bad thing, just not normal.

It doesn't change the fact something seems screwy.
I think most of the screwiness is how you are using the clamp on meter. This not the normal way to use an ammeter and you are getting all sorts of crazy results because of that. You have steel conduit, up to 6 wires carrying current, and possibility paralleled neutrals to add to the craziness.
 
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Old 04-17-14, 11:41 AM
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With the shared neutral scenario I present, do you think I need an electrician here?

At the least that would mean the circuits are still sharing a neutral and would be a shock hazard without handleties... that is not so much my concern though. Is this a fire, overheating hazard? As stated the two circuits are on opposite legs of the service.

I would be hard pressed to find an electrician to after the holiday.

I think most of the screwiness is how you are using the clamp on meter. This not the normal way to use an ammeter and you are getting all sorts of crazy results because of that. You have steel conduit, up to 6 wires carrying current, and possibility paralleled neutrals to add to the craziness.
This is where I am confused as I am reading difference of opinion here. its reading the conduit as one conductor, just like you would a single wire. I assume the wires inside are shielded by the metal, and it is indeed the conduit itself I am reading as a lone conductor.

But then I also read as you said that I am reading an unbalanced current on the conductors inside.
 

Last edited by ardmi; 04-17-14 at 12:05 PM.
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Old 04-17-14, 12:09 PM
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Shock hazard? Not really. The code for handle ties did not go into effect until 2008 or 2011. IMO - it is a poor rule as it encourages working circuits hot in my line of work.

Fire hazard? No.

I see your point of basically using the conduit as "one wire" however I wonder how the steel of the conduit plays into the mix by blocking the magnetic field created by current in the wires. If the meter was "seeing" the conduit and wires as a single conductor, it would be reading everything in that conduit as well. This would also involve some canceling between similar circuits.

Just for fun, have you tried taking a reading at the main panel and putting the clamp on meter around all the wires going into that conduit? I am curious what kind of reading you would get with and without the heat gun load.
 
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Old 04-17-14, 01:33 PM
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Just for fun, have you tried taking a reading at the main panel and putting the clamp on meter around all the wires going into that conduit? I am curious what kind of reading you would get with and without the heat gun load.
Unfortunetly I wasn't able to as the 6 wires in that pipe are squished in deep enough I cant get the clamp around it without taking it all apart.

That would have answered my question with certainty if my reading was flow on the conduit or flow on the conductors inside.

Does the fact that there are 6 wires in that conduit (3 connected to bus bar 3 ungrounded) tell you anything about balanced returns with the mwbc stuff I mentioned in mind?
 
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Old 04-17-14, 02:07 PM
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Hello ardmi....

I believe your question has been answered many different ways here. The pros here have giving you some great advice. After reading this thread, it is rather frustrating as it seems the questions and answers are going in circles..


With the shared neutral scenario I present, do you think I need an electrician here?

IMO I feel it would be best at this point to consult a pro.. Even though this is a DIY site I believe a physical person/licensed electrician in your home will be best equipped to answer your questions and rectify your issue/concerns.

It seems it is beyond the scope of this forum to assist you any further.

I do hope after you have the professional troubleshoots your issue you will post back with the information he gives..

Possibly it will help others here in the present and future..

Thank you for being a member and we hope to help you with further DIY projects you may have..

Thanks for your understanding.... The first round is on me....
 
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Old 04-17-14, 02:33 PM
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Yeah whatever, nice way of saying 'get lost' I think.

I think Chandler has the answers I am looking for, but the cats got his tounge
 
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Old 04-17-14, 03:15 PM
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No Chandler (who I believe hold a electricians ticket in his state, and an associates degree in the field) doesn't have an answer, nor does TI who is a licensed electrician with years of experience. It's apparent that you don't really have the electrical knowledge to continue on your own. Your use of volts when you meant amps in your earlier posts is one indication of that. You continue to talk about the conduit carrying current...it's not. You were advised to check the wires in the panel from that conduit, but you say they are squished in deep...well, that wouldn't stop an electrician with the proper tools and experience.

Think of someone posting here that says their car has a weird knock or thump. All anyone can do over the Internet is advise of the most LIKELY issues based on information provided.

I just got back from my doctor because of unexplained heel pain. Not much he can do til I get my x-ray done and he gets the results back. He gave me possibilities but nothing definitive.

Think of your own field, whatever it may be. Have you ever had someone ask you questions that were just impossible to answer without all the info or actually being there?

That's what has happened here...if you can't get to the individual wires in the conduit somewhere in the run or in the panel...not much more help can be given.

No hard feelings are held by anyone, nor are we saying get lost. It's just that you may get frustrated as the responses taper off to nothing.
 
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Old 04-17-14, 08:25 PM
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I just got back from my doctor because of unexplained heel pain. Not much he can do til I get my x-ray done and he gets the results back. He gave me possibilities but nothing definitive.

Did your doctor mention plantar fasciitis? I had it last year and was able to cure it in about 3 or 4 months once I used the right stretching exercises. I learned it was quite common.
 
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Old 04-17-14, 10:17 PM
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Not to go OT...but different pain. Wife had PF as did I a long time back, and it isn't like that.
 
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