High resistance reading neutral to equipment ground

suemarkp

Senior Member
Location
Kent, WA
Occupation
Engineer
If N-G resistance is high and voltages under load are good, that implies the bad connection is in the grounding wire path. A high resistance doesnt affect voltage readings when no current flows. A meter doesnt drag down the voltage because it has virtually no load. Try running a load from hot to ground instead of hot to neutral and see if that heavy load functions (a big power saw is a good test because you can tell if it doesn't sound right).
 

AC\DC

Senior Member
Location
Florence,Oregon,Lane
Occupation
EC
How did you test for L-N on each phase. You need to have a Large current imbalance on one phase to find help find a voltage swing.
tun on all A phase and find what’s working and load it up, the. Take your reading, and then swap it. bring a heater and heat Gun to help. Don’t rely on the power company to find it they generally never do in my area.
 

kwired

Electron manager
Location
NE Nebraska
How did you test for L-N on each phase. You need to have a Large current imbalance on one phase to find help find a voltage swing.
tun on all A phase and find what’s working and load it up, the. Take your reading, and then swap it. bring a heater and heat Gun to help. Don’t rely on the power company to find it they generally never do in my area.
And they shouldn't be expected to find resistance from neutral to EGC, that has to be something load side of service equipment.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Perhaps I missed it, but in this thread I haven't seen that the N-G voltage was measured on the problem branch circuit. As kwired mentioned in post #5, if the branch circuit came from a subpanel then there might be a voltage drop on its feeder neutral due to the current in other branch circuits. Although a multi-meter measures resistance by applying a DC current, measuring the resulting DC voltage, and then using R = V /I, if there was any AC voltage present that might mess up the resistance measurement. That's why the N-G voltage should be measured first to confirm that it's negligible. Since this has been a problematic case, it might be best to make a DC voltage measurement as well as an AC one on N-G.

Unless it's already been done, turning off the main breaker before making the N-G the resistance measurement should eliminate the possible neutral voltage drop issue from other circuits that's mentioned above.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Normal voltage drop on a feeder neutral and/or a branch circuit is not going to blow up a television set.
No, but it might be messing up the OP's N-G resistance measurements and therefore causing him to go on a "wild goose chase" if his measurements of 33 to 98 ohms are not valid.
 

AC\DC

Senior Member
Location
Florence,Oregon,Lane
Occupation
EC
And they shouldn't be expected to find resistance from neutral to EGC, that has to be something load side of service equipment.
If a tv really did blow up then it’s either a lose neutral connection on a multi wire, loses neutral connection at sub/main/meter, or at the pole. Every time I have these issue it’s the power company problem.
Though if his reading are correct .You would be right it would not be a power company issue
 
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