Grounding a system.

Status
Not open for further replies.
M

Miguel c

Member
Location
Barranquilla colombia
Occupation
Bilingual agent
Article 100 of the NEC defines ground as “the earth.” Section 250.4(A)(1) states that grounded electrical systems “shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.” The question is,
How does grounding a system stabilize the voltage to earth during normal operation? Who could please translate that in simple terms to me? The code does not explian it deeply.
 
An ungrounded system has a voltage to earth that varies with the capactance of the circuit. A grounded system has a stable voltage to earth under normal operation.
 
When you have ungrounded systems where permitted you can get some pretty wild and unstable voltages due to capacitive effects. This part of why we still bond all non current carrying components even with a non grounded system.

If you have basic 120-0-120 single phase system, that 0 remains stable voltage to earth if it is grounded, and the two 120 legs also remain 120 to earth.
 
kwired said:
When you have ungrounded systems where permitted you can get some pretty wild and unstable voltages due to capacitive effects. This part of why we still bond all non current carrying components even with a non grounded system.

If you have basic 120-0-120 single phase system, that 0 remains stable voltage to earth if it is grounded, and the two 120 legs also remain 120 to earth.
Click to expand...
Thank you very much I got it now, you explained in an easy and efficient way
 
To add: Locally speaking, the earth is not considered to be a good conductor.

However, on a larger scale, earth behaves like it's almost as conductive as wire.
 
LarryFine said:
To add: Locally speaking, the earth is not considered to be a good conductor.

However, on a larger scale, earth behaves like it's almost as conductive as wire.
Click to expand...
My understanding has long been earth is a good conductor. It is difficult to make a low resistance connection to it though.

Utility systems using a MGN do have pretty low resistance to earth simply because of the thousands of electrodes connected to them.
 
Status
Not open for further replies.
Top