DMM read on ground - neutral mains

Thread Starter

abdulbadii

Joined Aug 30, 2017
87
DMM set in AC V and one of If its probe on ground the other on N (neutral) gives ~21V (unstable read ~ 7-33V) instead of 0V, how can there's some electric potential here, is it always AC or a chance being DC ?
while AI chat hints:


  1. Stray Voltage
  2. Grounding Issues
  3. Imbalance in the Circuit
  4. imperfect MM itself

Help elaborate it crystal clear
 

MaxHeadRoom

Joined Jul 18, 2013
28,825
Most modern meters are high impedance devices, They will react to many stray currents that may be present. you need to place a low resistance, 1k e.g. , across the leads a see if the signal is sustained.
 

crutschow

Joined Mar 14, 2008
34,837
If you are going between the safety ground wire and neutral, then is sounds like the neutral and ground are not connected together at the breaker box as they should be.
 

tautech

Joined Oct 8, 2019
409
Phantom voltages exist, for one reason or another.
A DMM with a LoZ range is needed to know it they might be dangerous or a real problem.
 

sghioto

Joined Dec 31, 2017
5,428
If you are going between the safety ground wire and neutral, then is sounds like the neutral and ground are not connected together at the breaker box as they should be.
That would depend on what year the house was wired and local building dept codes and country.
Mine was on the 2017 electrical code but the neutral and ground only connect at the service pole, a hundred feet from the house.

:confused:
 
Last edited:

crutschow

Joined Mar 14, 2008
34,837
To check if there is indeed a connection, connect a 9V battery in series with an LED and a 1kΩ resistor between the neutral and ground, and see if the LED lights.
 

DickCappels

Joined Aug 21, 2008
10,246
I have a similar situation at my house and I chalk it up to the Neutral and Ground being tied together at the utility pole that has the transformer. Been in the house over 15 years and so far, no problem.
 
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