Across the UC, I mean. I am assuming this is an open ground. The house has knob and tube and some old romex added on. I am guessing that the ground on this circuit is just floating and maybe touching something or other in the house, but not actually tied to anything that is an actual ground. Would 500-1000 feet of ground wires made up in 20 or so boxes just absorb half of the voltage? That is what I am assuming.
65 volts on the ground wire
- Thread starter danickstr
- Start date
- Status
cadpoint
Senior Member
- Location
- Durham, NC
I got more questions than you presented! 
I'll ask only one question!
Is this the weekend job, the call that comes in after hours, or your talking yourself through it, now?
MO
This is a job for the screw-driver, a good flashlight and the bag of diagonics tools!
Amp clamp, amp probe, tracers, needles, and the dreader voltage screamer, and a radio, the 130V caged
lamp, the 3 conducts off of a real receptacle and maybe multiplies of anything listed, or not listed!
If you got that stuff together you can find the cause and do a repair!
Here's some questions for the Owner!
Ask them if they been dancing in the house lately, any lite construction,
or the dreaded thunder storms ? What did they unplug lately, the A/C?
Did they lay carpet even worst new flooring, You get the idea !
Hope that helps, let us know!
I'll ask only one question!Is this the weekend job, the call that comes in after hours, or your talking yourself through it, now?
MO
This is a job for the screw-driver, a good flashlight and the bag of diagonics tools!
Amp clamp, amp probe, tracers, needles, and the dreader voltage screamer, and a radio, the 130V caged
lamp, the 3 conducts off of a real receptacle and maybe multiplies of anything listed, or not listed!
If you got that stuff together you can find the cause and do a repair!
Here's some questions for the Owner!
Ask them if they been dancing in the house lately, any lite construction,
or the dreaded thunder storms ? What did they unplug lately, the A/C?
Did they lay carpet even worst new flooring, You get the idea !
Hope that helps, let us know!
Where are you taking the reading from ? , main panel , recpt., switch ?
#2. I don't believe voltage gets absorbed.
e57
Senior Member
- Location
- San Francisco, CA
Hmmmmmm....... your post(s) are hard to decipher.
A solid 65V, or a soft 65v?
Outside of this - what is the problem? What else doesn't work?
One could assume with K&T that the ground is not connected to anything, unless you have seen it in a panel. See if the voltage disappears with a small load ground to neutral.
It (voltage) could be asorbed as it is serving as an open (illegal) neutral conductor - 65 could be what is left over after the load measured open in series.
A solid 65V, or a soft 65v?
Outside of this - what is the problem? What else doesn't work?
One could assume with K&T that the ground is not connected to anything, unless you have seen it in a panel. See if the voltage disappears with a small load ground to neutral.
It (voltage) could be asorbed as it is serving as an open (illegal) neutral conductor - 65 could be what is left over after the load measured open in series.
Last edited:
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
What is a "UC"?
Therefore I am assuming you used a DMM and no load to attain this reading.
Use a DMM at the same time you apply a load to the circuit, with a solenoid tester or whatever else you can readily use. If the voltage disappears under load, the 65v is likely induced onto the EGC by the circuit conductors contained in the same cables as the EGC.
Flex
Senior Member
- Location
- poestenkill ny
Ungrounded Conductor?
Jason E De Lorenzo Sr
Member
Did any one try to drain the spair electricty out of a peice of wire like you would with a garden hose?
GUNNING
Senior Member
- Location
- Gainesville, Florida
Some of that there magic smoke got on that thar ground wire. yup
I am going to ignore the 5th grade level comments.
Yes UC is ungrounded conductor. I just haven't had the chance or OK from owner to go snoop around in the attic, to see if the romex from the 80's was ever actually tied to a grounding mechanism, or is just flopping around loose.
I simply wondered if 65 volts on a Fluke 600 DMM told anyone anything based on their experience.
I did wonder if it is induced and read by a DMM, that is possible George, but the UC to Neutral is a good 121V.
Putting a load on it and taking measurements is a next step, and finding the ground and attaching it to something is probably is all that is needed in this case.
Yes UC is ungrounded conductor. I just haven't had the chance or OK from owner to go snoop around in the attic, to see if the romex from the 80's was ever actually tied to a grounding mechanism, or is just flopping around loose.
I simply wondered if 65 volts on a Fluke 600 DMM told anyone anything based on their experience.
I did wonder if it is induced and read by a DMM, that is possible George, but the UC to Neutral is a good 121V.
Putting a load on it and taking measurements is a next step, and finding the ground and attaching it to something is probably is all that is needed in this case.
Last edited:
Power Tech
Senior Member
- Location
- Lebec, California
I am going to ignore the 5th grade level comments.
Yes UC is ungrounded conductor. I just haven't had the chance or OK from owner to go snoop around in the attic, to see if the romex from the 80's was ever actually tied to a grounding mechanism, or is just flopping around loose.
I simply wondered if 65 volts on a Fluke 600 DMM told anyone anything based on their experience.
I did wonder if it is induced and read by a DMM, that is possible George, but the UC to Neutral is a good 121V.
Putting a load on it and taking measurements is a next step, and finding the ground and attaching it to something is probably is all that is needed in this case.
You would get a reading between your phase conductor on a coil of wire not connected to anything.
If this ios knob and tube / sell them a rewire. Say fire 3 times. If it is? Abandon it, run a new circuit from the panel, and be careful in the attic.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
I'll make the following assumptions:
You are taking a reading from an UC to a bare wire in a piece of romex.
You are using a DMM with no load at the test point.
You are reading capacitance on the bare wire since you said the reading from UC to GC is solid.
Did you try to take a reading with your DMM from the UC to the bare wire? If so, what was the reading?You are using a DMM with no load at the test point.
You are reading capacitance on the bare wire since you said the reading from UC to GC is solid.
Is this your home, a service call, or ??? Just curious as to what started you looking.
growler
Senior Member
- Location
- Atlanta,GA
When you say the house is wired in Knob & tube with old romex added on are we talking about new grounded circuits being added or is the romex being used to extend the knob & tube circuits?
If these are ungrounded circuits then why are you wanting to hook up a ground? Did they replace the old two prong receptacles with three prong grounded receptacles?
You really need to be carefull what you hook a ground wire to because it's fairly easy for the bare ground to become energized ( it's in a box filled with live conductors ).
You can't just attach a ground wire to "something" it has to be part of the grounding electrode system.
Read article 251-130 (C) (1) which takes you to articel 250-52.
If you need three prong receptacles the safest way is to use GFCI protected receptacles with a no equipment ground sticker.
e57
Senior Member
- Location
- San Francisco, CA
I hope you don't use this as a sales tactic????
Power Tech
Senior Member
- Location
- Lebec, California
It is a permitted job where they are adding onto existing. Thanks for more intelligent responses than a couple from last go around.
Everyone has some good suggestions and many need more info, but I can't get back there til Tuesday (was that a band?).
I am still of the opinion that it's probably just a handyman had tied into K&T without addressing the ground, somewhere back in the attic in the 80's or 90's, judging by the wire.
My original question was more of a passing curiosity about the ghost readings of my DMM than anything else, and if it would be a good guess to just assume it was a "fluke" due to an open ground and a DMM, with the readings of the DMM creating a phenomenon that appears like the other 55 volts get absorbed by the UGC network.
I am not of the belief that K&T is fire prone, unless it has been altered by ignorance, which is usually the case after 80 years.
Everyone has some good suggestions and many need more info, but I can't get back there til Tuesday (was that a band?).
I am still of the opinion that it's probably just a handyman had tied into K&T without addressing the ground, somewhere back in the attic in the 80's or 90's, judging by the wire.
My original question was more of a passing curiosity about the ghost readings of my DMM than anything else, and if it would be a good guess to just assume it was a "fluke" due to an open ground and a DMM, with the readings of the DMM creating a phenomenon that appears like the other 55 volts get absorbed by the UGC network.
I am not of the belief that K&T is fire prone, unless it has been altered by ignorance, which is usually the case after 80 years.
e57
Senior Member
- Location
- San Francisco, CA
Prove it!
Properly done and maintained it is just as safe as any other wiring method IMO. When manipulated by people with little understanding of the methods, and / or buried in insulation is when problems arise. Many of these issues are addressed in your code book.
Since many K&T installations were done in an era before circuit breakers - over-fusing was what resulted in fires - not the wiring method IMO.
e57
Senior Member
- Location
- San Francisco, CA
Two good solutions- thanks heretic. I always see ghost voltages here and there on, for example, three way travelers, etc. But never realized it was due to the high impedance on my DMM. I just stopped looking for a problem when experience had shown me there was nothing wrong with my circuits. I apprenticed with wiggies in the 80's so I sort of taught myself about DMM's and volt pens, and their tendency to pick up ghost voltage. Tore apart a few installs for no good reason til I figured out it was just GV.
e57
Senior Member
- Location
- San Francisco, CA
I have never been fond of the term "Ghost" or "Phantom" voltage - it is VOLTAGE - but not a usable hard voltage. While finding a voltage reading 50% or < of the nominal voltage could be capacitive, it very well could also be measured in series on an open conductor on the otherside of a load, or some other thing like a loose connection, or over-load happening at the time. (Like a stalled motor at the end of long conductors) Just have to know what your measuring and what type of reading you are getting particular to that situation - not just say it's this or that, and dismiss it...
- Status