Grounding Myth Busted
One of the Most Popular Grounding Myths is “Current goes to ground”. This is a dangerous belief that contributes to the misapplication of Grounding and Bonding which is found in Article 250 of the NEC. In an electrical system, current returns to the source (typically the transformer) and are not trying to return to the ground as highlighted in the article.
In a ground a fault, the earth is not a part of the effective ground-fault path per section 250.4(A)(5). There is very little current that will go to earth during a ground fault because the contact resistance of the grounding electrode(s) is too high when compared to the low impedance ground fault path back to the supply source (typically the transformer) per sections 250.4(A)(3),(4),(5). The effective ground-fault current path is required to open the overcurrent protective device (Circuit Breaker or Fuse).
If the Earth was used as the ground fault path as highlighted in the article, this would create a serious hazard because the overcurrent protective device (circuit breaker or fuse) will not open to clear the fault current and can cause loss of life and or property.
Now we are back to earth from this Grounding Myth. Why Ground? We ground to limit voltage induced by lightning, line surges or unintentional contact by higher voltage lines. Additionally, to reduce arching and electrical shock from lightning.
March 23, 2020, “Grounding and Bonding” Author: David Harsche