No change, tested at panel with hair dryer on
My personal home has current on #6 to water pipe.
- Thread starter Eamp
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No change, tested at panel with hair dryer on
No change, so the line with the hair dryer on went to 102 volts, and with the dryer running the other line stayed at 120 volts.
help me here, you got to give me some numbers to work with...
I tested from his room with the hair dryer on and it drops to 111v at the prongs from the hair dryer. Went into basement and tested both phases at panel with hair dryer running still and both phases @120v
I plugged the hair dryer in a 100 ft extension cord in basement and it dropped to 102v and then checked at panel and both phases 120v at panel with hair dryer still running
Ok, you have a bad neutral from his room to the panel. My bet would be a loose neutral in the panel.
you can pinpoint it by leaving the dryer on and checking the phase to ground voltage at a couple different places in the panel, only moving the probe on a neutral to different neutrals. Leave the phase probe in one spot.
Tighten all the neutral connections in the panel
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I said "neutral issue" to myself as soon as I started reading the OP.
Eamp, check to see if the rooms with the issues are on circuits that share a 3-conductor cable in the panel.
Eamp, check to see if the rooms with the issues are on circuits that share a 3-conductor cable in the panel.
Sent PM
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
190918-2343 EDT
Eamp:
As an electrician your training is clearly lacking in providing you with an understanding of electrical circuit theory, and troubleshooting methods.
For most homes the power company will supply three wires from a transformer to your main panel. Two of the wires can be classified as hot as a convenient name, and one as a neutral.
The neutral is earthed at the power company transformer.
These three wires ultimately terminate in your main panel on three buses. There is also a grounding bus in the main panel. This grounding bus is connected to (bonded) the neutral bus, as is the main enclosure. The grounding bus, and thus the neutral, are connected to a grounding electrode. Under normal conditions the difference in voltage between any of the different things wired to the neutral bus (power company ground rod, ground bus, local ground electrode, and main enclosure) should be small under worst case loading of the main panel. Millivolts to several volts. Several volts would be unusual, a 200 A load from neutral to one hot would be unusual.
Without a meter you can use two 15 W incandescent, or larger, bulbs to look for neutral problems. 15 W is easier on the eyes. If you have a high resistance neutral, and load one phase to neutral, then one bulb will get brighter, and the other dimmer. If one bulb remains about constant, and the bulb on the loaded side gets dimmer, then you have a high resistance in the hot supply line on the loaded side.
The two bulb method is useful when you want an easy way to see what is happening, or when you have only one meter. Also simultaneously reading two meters is harder than viewing two adjacent bulbs.
Some of your comments seem to be unrelated to the problem, or seem to be misleading.
I don't have any more time now.
.
Eamp:
As an electrician your training is clearly lacking in providing you with an understanding of electrical circuit theory, and troubleshooting methods.
For most homes the power company will supply three wires from a transformer to your main panel. Two of the wires can be classified as hot as a convenient name, and one as a neutral.
The neutral is earthed at the power company transformer.
These three wires ultimately terminate in your main panel on three buses. There is also a grounding bus in the main panel. This grounding bus is connected to (bonded) the neutral bus, as is the main enclosure. The grounding bus, and thus the neutral, are connected to a grounding electrode. Under normal conditions the difference in voltage between any of the different things wired to the neutral bus (power company ground rod, ground bus, local ground electrode, and main enclosure) should be small under worst case loading of the main panel. Millivolts to several volts. Several volts would be unusual, a 200 A load from neutral to one hot would be unusual.
Without a meter you can use two 15 W incandescent, or larger, bulbs to look for neutral problems. 15 W is easier on the eyes. If you have a high resistance neutral, and load one phase to neutral, then one bulb will get brighter, and the other dimmer. If one bulb remains about constant, and the bulb on the loaded side gets dimmer, then you have a high resistance in the hot supply line on the loaded side.
The two bulb method is useful when you want an easy way to see what is happening, or when you have only one meter. Also simultaneously reading two meters is harder than viewing two adjacent bulbs.
Some of your comments seem to be unrelated to the problem, or seem to be misleading.
I don't have any more time now.
.
growler
Senior Member
- Location
- Atlanta,GA
There has been nothing said that would indicate a bad neutral. Not a single voltage measurement mentioned is above 120V.
Unless you are dealing with a MWBC you don't really have a neutral you have a return path. A bad connection anywhere along the path can cause a larger than normal voltage drop. Even a bad connection on the return.
You are right and it could be a loose connection at the neutral bar but that's not a bad neutral that's a bad connection and will only add resistance to the circuit..With a loose connection like that there will never be a power surge (over voltage ) situation.
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
Back stabbed receptacle? 
growler
Senior Member
- Location
- Atlanta,GA
Back stabbed receptacle?
Could easily be a bad back stabbed receptacle. I have seen a lot of them that caused a higher than normal voltage drop on a circuit.
And it can be a bad connection on either the hot or return side. The resistance added by poor connection will be the same.
Now your arguing semantics...
if it’s loose it isn’t good, ergo, it’s bad...
if you were there , had the panel open checking, would you tighten the neutrals while you were in there first?
Its a starting point that clearly was needed, and with currents on the #6, it seemed a good place to start.
from there he could start pulling outlets, or looking elsewhere,
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
190919-0744 EDT
Eamp:
In post #24 I believe you said that at the main panel both phases read 120 V to neutral for a hairdryer change of load on one of the phases somewhere else. I will assume a hairdryer is about a 10 A load.
I have a 1500 W 120 V space heater that I use as a test load. When warmed up it is about 10 A and cold about 11 A. Its exact value is not too important for these tests. However, accurate voltage measurements are important because under normal conditions we don't expect much voltage change.
Whether your test load is at the end of a long cable, or right at the main panel is not important relative to tests at the main panel.
With a 10 A load change you should see some voltage change at the bus bars of the main panel.
At my main panel today when I ran a test phase A read 123.8 V, and B read 123.9 V. Whatever loads I have on at the moment they are moderately well balanced.
Adding an unbalanced heater load of about 10 A phase A changed to 124.1, and B to 122.9 . The A change is +0.3 V, and B is -1.0 V. Thus, the load was added to phase B. That the B change is somewhat more than 2 times the A change is to be expected. But I won't discuss that.
That you did not see a change in phase to neutral voltages at the main panel with an about 10 A change in load means you do not have a power company, or main panel problem. At least to the bus bars.
If I understand your 100 ft extension cord test it does not mean much other than I suspect it is #16 wire.
An extension cord can be useful for troubleshooting your problem, but not from the aspect of how I understand you used it.
Now to what you need to do.
At the main panel get more accurate readings of the voltage changes with you hairdryer load. Also it would be somewhat useful to know the approximate load current of the hairdryer.
Install two duplex receptacles at your main panel, one on each phase. Ideally these should be on their own breakers. If not feasible, then on breakers that are not related to the circuits where you have problems.
Your 100 ft extension cord will be a long test lead from the main panel to wherever you want to make measurements. That it is #16 is no problem, or even if it was #30, because your voltmeter load current on that test lead is only in the microampere range.
The extension cord provides three test leads into the three buses in the main panel.
Use the extension cord EGC lead as your primary reference point. Make it the black lead to the meter.
Go to a location where you think you have a problem. Provide a way to connect your hairdryer as a load at this point. With and without the load measure the problem location neutral, and hot voltages to the extension cord EGC, and report back.
.
Eamp:
In post #24 I believe you said that at the main panel both phases read 120 V to neutral for a hairdryer change of load on one of the phases somewhere else. I will assume a hairdryer is about a 10 A load.
I have a 1500 W 120 V space heater that I use as a test load. When warmed up it is about 10 A and cold about 11 A. Its exact value is not too important for these tests. However, accurate voltage measurements are important because under normal conditions we don't expect much voltage change.
Whether your test load is at the end of a long cable, or right at the main panel is not important relative to tests at the main panel.
With a 10 A load change you should see some voltage change at the bus bars of the main panel.
At my main panel today when I ran a test phase A read 123.8 V, and B read 123.9 V. Whatever loads I have on at the moment they are moderately well balanced.
Adding an unbalanced heater load of about 10 A phase A changed to 124.1, and B to 122.9 . The A change is +0.3 V, and B is -1.0 V. Thus, the load was added to phase B. That the B change is somewhat more than 2 times the A change is to be expected. But I won't discuss that.
That you did not see a change in phase to neutral voltages at the main panel with an about 10 A change in load means you do not have a power company, or main panel problem. At least to the bus bars.
If I understand your 100 ft extension cord test it does not mean much other than I suspect it is #16 wire.
An extension cord can be useful for troubleshooting your problem, but not from the aspect of how I understand you used it.
Now to what you need to do.
At the main panel get more accurate readings of the voltage changes with you hairdryer load. Also it would be somewhat useful to know the approximate load current of the hairdryer.
Install two duplex receptacles at your main panel, one on each phase. Ideally these should be on their own breakers. If not feasible, then on breakers that are not related to the circuits where you have problems.
Your 100 ft extension cord will be a long test lead from the main panel to wherever you want to make measurements. That it is #16 is no problem, or even if it was #30, because your voltmeter load current on that test lead is only in the microampere range.
The extension cord provides three test leads into the three buses in the main panel.
Use the extension cord EGC lead as your primary reference point. Make it the black lead to the meter.
Go to a location where you think you have a problem. Provide a way to connect your hairdryer as a load at this point. With and without the load measure the problem location neutral, and hot voltages to the extension cord EGC, and report back.
.
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
i believe a fluke 345 can do this, but not a commonly used piece of test equipment.
growler
Senior Member
- Location
- Atlanta,GA
I know it may sound like I'm arguing semantics here but I'm not, I'm not even arguing, I'm pointing out the fact that the bad connection is just as likely to be with the black wire as the white wire. The symptoms will be the same if the connection is loose at the breaker as at the neutral bar.
If the problem is just as likely to be on the black conductor as the white then why would we want to call it a bad neutral?
Frank DuVal
Senior Member
- Occupation
- Electrical Contractor, Electrical Engineer
Also the Fluke 434 and 435.
Yes, not typical, since $8k! I've had to use one.
growler
Senior Member
- Location
- Atlanta,GA
I kind of hate to ask this but what type of speed control are you using with these fans? Pull chain, remote, box mounted control or what ever?
It was somewhere to start with what apparently was an apprentice electrician.
I agree it could also be a black wire problem, but with the voltage drops, and him being unable to provide other phase voltage at the correct place, how are we to know it isn’t a bad neutral? Actually, the black wire came to mind with him saying the fans are hot. Low voltage, motor overheating. Don’t know why the tv got hot though...
kinda went the other way when he said the cases got hot fast. Now I’m assuming a bad neutral on at least that circuit and return currents going back to source through the bare ground on the Romex...
He provided phase voltages to ground at the plug in question with an 18V drop. I really wanted a phase voltage on the other phase somewhere at that area ( if there was one) rather than at the panel where he took his measurements. He could have very well been taking his measurements at the panel on top of the main at the SE cable. Who knows? If it’s a bad connection in the panel, there it is... I was hoping for maybe a loose wire for that circuit only by the postings.
If that didn’t fix it, at least that has been ruled out, and it was a good and most logical place to start in reading the posts.
the entire thread was a head scratcher. We were back and forth, then the conversation stopped abruptly.
I hope the problem was found and he simply fixed it and went to bed...
we will see later if he posts again..
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
You could troubleshoot the Neutral issue, or you could isolate your piping like this guy https://www.youtube.com/watch?v=U2iejrZsXkM :lol:
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