Why are we not allowed to measure voltage from the neutral wire to the ground wire in an electrical system?
Most electrical engineers do not recommend measurement of Voltage with regards to neutral wire and ground wire due to considerations of safety and functionality.
Here are the key reasons:
Safety Concerns
Potential Voltage Difference: At the same time, there may be a small voltage difference between the neutral and ground for various reasons, for example, the presence of the current within the conductor of the neutral-wire. This can then give a wrong perception of identifying a fault or a condition of collapse, which then makes people to undertake unsafe practices or even assume that the Electrical system is safe enough.
Fault Conditions: The ground wire is mainly a protective, which is intended to execute current only during faulty circumstances. If you read voltage between neutral and ground when everything is operating normally, they you may unknowingly put a path for current flow that may lead to electric shock or rack damage.
Operational Issues
Interference with Circuit Function: Measuring voltage between neutral and ground can somehow destruct the standard functioning of the electrical system. It can produce ambiguity on the real working of the circuit specially for circuits where the neutral is connected to the ground at the service entrance. This bond is utilized to attempt at providing some measure of stability to the voltage reference point in the system.
Regulatory Compliance: According to the electrical codes and standards, neutral and ground should be considered being different from one another as far as their functions are concerned. Earthing is meant for safety while neutral is meant for carrying current back. Interchangeability of these purposes may cause violation of safety measures and norms that were adopted for people’s and equipment’s sake.
Therefore, impedance voltage measurements between the neutral and ground wires can endanger lives, give wrong system indications and which is violation of most regulatory codes hence most electrical practices do not permit it.