chasing a ground problem

ATSman

ATSman
Location
San Francisco
Occupation
Self Employed
I know this ? will be off from OP but, how are you using an ohmmeter to check torque? Torque is a mechanical measurement.
Fred,
Yes that's a good question and you are correct. But if the bus bars have loose connections or corrosion between the joints then it will show up as a high resistance reading since the ductor is so sensitive. This is a tried and true method of checking the integrity of a bolted connection, breaker contact condition, etc.
I suggest you do some research on the subject:
 
I also have seen way to many questionable indoor systems that rely on the conduit for ground just for the fact of lazy people not tightening set screw couplings and or connectors.....way to many....
So these lazy people who do shoddy work will do a good job making the wire EGC connections but not the conduit connections? That is interesting.

I think to offer more advice on the problem, we would need to know specifically where your voltage measurements were taken and if you used a low or high impedance meter.
 

laz

Member
Location
PNW
Occupation
electrical contractor owner/operator
RE............ So these lazy people who do shoddy work will do a good job making the wire EGC connections but not the conduit connections? That is interesting.

I honestly don’t understand why you take exception to this comment........and “shoody work” is your word not mine........ that is interesting

Take out the word lazy and use “ tired, hung-over, over worked, burned out, lack of attention, absent mindedness, confused, apprentice, journeyman, etc. etc. etc..... it happens to all of us.....my point was i agreed with the WADOT requiring a physical wire in lieu of just relying on the metal conduit system. And yes, it could be overlooked and or under tightened also..........part of life..........it happens.....

One individual apt. coax, RG-6, was removed from the splitter in the demarc box and the test leads were put on the end of the coax and on to the splitter itself. There is no utility ground of any kind in any of the demac boxes that i had access to and or i could find.......so the only ground it is reading to is off the main coax attached to the splitter. ....where it is getting it’s ground is unknown to me..... i ass-u-me it is off the pole it drops from or at the very worst all the way back to where it gets it ground from the cable company....

So the coax tested was removed from the splitter at the demac box.....and the other end went directly into one of the apartments which that specific run was assigned to..... It was terminated at a splitter in/on the wall of the apt. approx. 4 - 6’ from the demarc box and one left there going directly into the bedroom and the other went along the wall approx 6 - 8’ and thru into the living room.....no other taps.... two total....each apt......all apts. the same...

High impedance meter........on voltage setting............

so....advice...or advise.... please...............

and i am really not trying to be a smart ass here.........just need to fix the problem..............and i do appreciate all the help all of you have freely given....thanks
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
RE............ So these lazy people who do shoddy work will do a good job making the wire EGC connections but not the conduit connections? That is interesting.

I honestly don’t understand why you take exception to this comment........and “shoody work” is your word not mine........ that is interesting

Take out the word lazy and use “ tired, hung-over, over worked, burned out, lack of attention, absent mindedness, confused, apprentice, journeyman, etc. etc. etc..... it happens to all of us.....my point was i agreed with the WADOT requiring a physical wire in lieu of just relying on the metal conduit system. And yes, it could be overlooked and or under tightened also..........part of life..........it happens.....

One individual apt. coax, RG-6, was removed from the splitter in the demarc box and the test leads were put on the end of the coax and on to the splitter itself. There is no utility ground of any kind in any of the demac boxes that i had access to and or i could find.......so the only ground it is reading to is off the main coax attached to the splitter. ....where it is getting it’s ground is unknown to me..... i ass-u-me it is off the pole it drops from or at the very worst all the way back to where it gets it ground from the cable company....

So the coax tested was removed from the splitter at the demac box.....and the other end went directly into one of the apartments which that specific run was assigned to..... It was terminated at a splitter in/on the wall of the apt. approx. 4 - 6’ from the demarc box and one left there going directly into the bedroom and the other went along the wall approx 6 - 8’ and thru into the living room.....no other taps.... two total....each apt......all apts. the same...

High impedance meter........on voltage setting............

so....advice...or advise.... please...............

and i am really not trying to be a smart ass here.........just need to fix the problem..............and i do appreciate all the help all of you have freely given....thanks
A high impedance meter can give you a voltage reading if the coax is run parallel to energized wires. More so if those wires have a load on them.
 

gar

Senior Member
201025-2143 EDT

Some useful information conduit impedance https://steeltubeinstitute.org/wp-content/uploads/2020/05/GROUNDIN.pdf
In particular see 4.2 .

As a useful guess, without adequate details, I will assume your conduit would be less than
0.5 ohms.

To test voltage drop on the conduit get a roll of #16 wire to make a long test lead from your main panel, and close to a point where main panel grounding is performed, your main panel neutral bus bar. Connect the test wire to the neutral, and run this wire to somewhere where you want measure the conduit resistance. Use a 1500 W 120 V space heater to inject about 10 A on the conduit. Measure the conduit voltage drop before turning on the heater. Turn heater on and measure the voltage change. You might power the heater from a different phase, and again observe the voltage change.

Report back. At this point I have no guess as to what you will see.

.
 
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