Unusual Voltage

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augie47

augie47

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Tennessee
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State Electrical Inspector (Retired)
AS new member sent me a p.m. with the following question asking our help:
This is my very first post and hope you can help me. I have a situation where a ceiling fan is not running at full voltage but when you plug in the refrigerator, the ceiling fan runs fine. (Weird). This is a first for me.:confused:
 
Is this a new installation or a problem that began on an existing install ?
 
Sounds like a loose neutral.
loose at a device box, the panel or even the service?
I had a couple in the last 2 weeks where the problem was the POCO connection of the neutral at the service. On one of the calls the POCO was out 3 times and told the HO they could not find anything wrong, but never once got on the roof to check the voltage at the connections.
 
aftershock said:
Sounds like a loose neutral.
loose at a device box, the panel or even the service?
I had a couple in the last 2 weeks where the problem was the POCO connection of the neutral at the service. On one of the calls the POCO was out 3 times and told the HO they could not find anything wrong, but never once got on the roof to check the voltage at the connections.
Click to expand...

I just went through this at my own home. The neutral connection in the meter socket was bad. The linesmen pulled the meter but wouldn't fix the connection. They said I needed to call an electrician.

:D:D:D:D:D

I said I would be right back with my tools.

The linesman said I couldn't work on the meter socket hot. I said 'bet me'. I told him I was going to fix the neutral one way or another, with him or without him.

He looked up at the triplex and told his partner that I needed new connectors. Then he told me that once I was snipped I could try to fix the connection. It was in pretty bad shape with melted metal and all that good stuff. I did my magic, got power back on and bingo!! Problem solved.

I chased that bad neutral from one side of the house to the other before I made the decision to get into the meter socket.

Bad neutrals can be a PITA to locate, especially in older structures, but it can be done. I am actually getting good at it, now.
 
100213-1739 EST

K8MHZ:

A suggestion.

If the transformer is in your backyard, then its ground rod is there also, and a little digging will expose the rod or the wire to it. Measure the voltage from the transformer ground rod to your main panel neutral buss. From this with high probability you can tell if there is a power company problem.

Also the two light bulb or two meter test at the main panel on the wires from the meter, not on the lugs, will tell you if the problem is before the main panel.

If the transformer is not in your backyard but some distance away and you do not want to or can not run a test wire from transformer ground to your test meter at your main panel, then drive a 12" screwdriver into the ground in a position that is in the path from the transformer to your panel. From this you can monitor the ground voltage and make an estimate of whether there is a bad neutral.

On various jobs you could run ground voltage tests to develop some experience of what to expect. I have some ground currents that run thru my yard that are not from my transformer and I can see step changes in these currents. My usual ground voltage levels are in the 100 MV range for a distance of 12 ft between two screwdrivers.

.
 
you have in all probability a multiwire branch circuit with a bad neutral connection. Had a 3 phase boat the other day where they could not get one flour lite plugged in to an ouitlet down a wall to work but if you turned on the chop saw closer to the panel the lite came on. the chop saw and the lite were on different phases. found the home run in an outlet box midway between and lo and behold the common splice point for the home run neutral was bad. the neutrals to the loads were ok but the home run point was not. fixed the splice and all was well. the way i explain this to my baffled helpers is to draw an E. the top of the E is one hot and the bottom is the other hot.the center is the neutral. all is well til you erase the middle leg of the E and EEEK !! not so good!!
 
gar said:
100213-1739 EST

K8MHZ:

A suggestion.

If the transformer is in your backyard, then its ground rod is there also, and a little digging will expose the rod or the wire to it. Measure the voltage from the transformer ground rod to your main panel neutral buss. From this with high probability you can tell if there is a power company problem.

Also the two light bulb or two meter test at the main panel on the wires from the meter, not on the lugs, will tell you if the problem is before the main panel.

If the transformer is not in your backyard but some distance away and you do not want to or can not run a test wire from transformer ground to your test meter at your main panel, then drive a 12" screwdriver into the ground in a position that is in the path from the transformer to your panel. From this you can monitor the ground voltage and make an estimate of whether there is a bad neutral.

On various jobs you could run ground voltage tests to develop some experience of what to expect. I have some ground currents that run thru my yard that are not from my transformer and I can see step changes in these currents. My usual ground voltage levels are in the 100 MV range for a distance of 12 ft between two screwdrivers.

.
Click to expand...

I use a slightly different method.

I think it's much better to know how to use test equipment in order to make sure the problem isn't on the HO side before making the call to the POCO. If I see a problem at the top of the main (or bottom of the meter if for some reason it is not locked and I can get to it), I know the problem is on the POCO's side. Also, eliminating HO side issues gives you a 'standard' that you can use to base the POCO's line integrity with.

I know your experiment will produce some results, but such effort is not needed. There is no need to dig up ground rods or even go outdoors. I can check for a bad connection from inside by taking readings with different loads on different legs (NOT PHASES) and making an analysis therein.

Perhaps you misunderstood me when I said I chased the problem all over the house. I didn't mean it baffled me, I meant that I spent time in various spots checking and repairing bad connections. After I got everything on the load side of the panel up to snuff, I still had issues. It took me less than 5 minutes to know I had a POCO issue once I gained access to the top of the ancient 60 amp fuse panel.

The currents you see in your own yard are also POCO issues. How it happens has been discussed here several times under the guise of stray currents or stray voltages. To go any further down that road would certainly put the thread at risk of a hijack.

I do thank you for your time and your suggestion. It's just that over the years I have developed very quick and accurate troubleshooting methods that I can trust, and trust every time. The very basis, though, is understanding how test equipment works and what the readings you get actually mean.
 
100214-1238 EST

K8MHZ:

I know you are well experienced at this type of troubleshooting, but many others are not.

At the main panel by monitoring the three input wires you can determine if there is a likelihood of a power company problem, but it could be on the customer side of the meter. If you can not open the meter or do not want to, then a voltage drop measurement in the yard can be useful. The best yard measurement is when you have access to the transformer ground rod. Otherwise just using the voltage gradient in the yard can provide useful information.

My two screwdriver 12 ft test is interesting to use to to identify the direction of the current. What I would like to try, but do not have the time, is a 8, 12, or 16 point test with continuous monitoring. This would provide better information on the changes in current and direction. Not useful to an electrician, but an interesting study.

.
 
All I did was check voltage from leg to neutral on the transformer side of the service drop connection and on the HO side to determine a bad service drop connection to the neutral was the problem.
 
gar said:
100214-1238 EST

K8MHZ:

I know you are well experienced at this type of troubleshooting, but many others are not.

At the main panel by monitoring the three input wires you can determine if there is a likelihood of a power company problem, but it could be on the customer side of the meter. If you can not open the meter or do not want to, then a voltage drop measurement in the yard can be useful. The best yard measurement is when you have access to the transformer ground rod. Otherwise just using the voltage gradient in the yard can provide useful information.

My two screwdriver 12 ft test is interesting to use to to identify the direction of the current. What I would like to try, but do not have the time, is a 8, 12, or 16 point test with continuous monitoring. This would provide better information on the changes in current and direction. Not useful to an electrician, but an interesting study.

.
Click to expand...

Gar,

If the next point I determine that needs to be checked is the customer side of the meter socket that is what will happen. So far, the POCOs have been very cooperative with me and if they can't get to my site in short notice they give me an OK to clip the tag and take measurements so long as they are notified when it's time to re-tag the meter. If I, for some reason, could not get cooperation I would snip the tag and pull the meter on a safety basis as we all know a bad connection there can be a fire hazard.

You have piked my interest as I have always wanted to check potential differences between electrodes in close proximity to the SDS versus close proximity to the served load. Here all the pigs are grounded with a bare solid #6 which is easy to tag for a reading without having to dig. I also would like to see what the potential is between transformers but that's not likely due to the amount of separation. At least here I can measure a distance of around 200 feet one way and 150 feet another way at a 90 degree angle for random ground voltage readings and I have about 170 feet between my pig and my meter for source to load readings.

I also want to see how much current limitation there is in this 'stray' voltage.

Since I live adjacent to a rural area that is likely to have single conductor with a ground return I may even pick up some of that current.

Some would consider this useless information but I know that there is always a chance that such information will suddenly become useful.
 
100214-2130 EST

K8MHZ:

Sounds like you have an ideal location in which to play.

I use about a 12 ft distance between two rods because this is about the distance with two Fluke extension leads on each side of the meter and a Fluke alligator clip to the screwdriver.

As you change the angle to the earth N E S W you will see a change in the voltage. The maximum voltage has the direction thru the two probes in line with the current vector, or direction of current flow. At least the composite current if currents are coming from more than one direction.

If you use a scope and line sync, then you could see if the phase shift changes with direction. I have not done this. Also might be desirable to use a phase lock detector and look at only the fundamental frequency. There might be currents from some other country or grid system not synced to us. Truly I do not know what to expect when doing very detailed signal analysis of what ground currents may exist.

One day I went out to see if there was substantial ground current below high tension lines. I was traveling around in the Waterloo area between Jackson and Ann Arbor and found a tie between DTE and Consumers. No excessive currents in the area.

.
 
K8MHZ said:
...
Since I live adjacent to a rural area that is likely to have single conductor with a ground return I may even pick up some of that current. ...
Click to expand...
I don't think there is any SWER systems in use in the US, but I could be wrong.
 
don_resqcapt19 said:
I don't think there is any SWER systems in use in the US, but I could be wrong.
Click to expand...

One in Alaska, occasional rural use in the Upper Midwest (I have heard of them in Michigan).

Remember the hype about the cow's not making milk because of electrical currents in the ground? In reality, it was found that SWER's actually WERE affecting livestock and it wasn't hype. It was also found that faults on the primary neutral of distribution lines had the same effect.
 
Gar,

I live a couple miles from Consumer's 315k backbone you may have found tied to DTE. I live a half mile from Consumer's 138k power lines and have a 44k drop across the street in addition to my 120/240 drop to the house.

I'll bet I would find some interesting currents from one side of my property to the other.
 
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