Forget the neutral. That might be a load current path but in a ground fault its not very important at all for the example which is utility systems.

A little known fact is that the conceptual idea we've been taught that electricity follows the path of least resistance is utterly false. It actually follows all paths proportional to their conductance which is the inverse of resistance. This becomes important when we move from a 1D system to grounding which is clearly 2D. As the ground electrode on say a pole gets further from the substation ground it would seem that resistance increases. On any given path this is true and it's basically linear but the number of paths between the two depends on the area between them so it's increasing with the square of the distance. So when we divide by the number of paths the surprising fact is that Earth resistance is proportional to the inverse of distance. Even though Earth isn't a great conductor usually about a mile away the resistance equals the neutral (which is increasing) and quickly surpasses it within a few miles to where effectively it's almost a dead short to the substation. Thus almost the entire voltage drop is over the hot and the neutral voltage drop is almost zero. You can verify this in the IEEE green book or just look at the formulas in any 3 point ground testing manual where you divide by the distance to get resistance. Within a typical structure there are tons of research papers that show that conduit resistance is far less than the neutral so once again, the neutral sees little to no voltage during a fault. It's only close to the transformer or within a substation, or close to a faulted transmission tower that ground potential rise or GPR actually becomes a serious safety hazard. Even then the danger isn't the fact that say the tower or the Earth is energized. It's the gradient or difference through the ground so foot to foot is the hazard. That's why they teach linemen to keep their feet together and shuffle or bunny hop if they are caught near a downed line and need to escape. So going back to the OP, there is little or no neutral voltage. To the post about SKM output that's at the transformer, not close to the fault.

The original Edison DC distribution systems used a single hot and peg grounding as the return. There were lots of safety reports near these systems, all GPR issues.

Today we use extensive grounding under substation yards and multigrounded and bonded systems everywhere else. Because of GPR line crews are moving to using equipotential grounding as well as ground grid blankets for ground men to reduce or eliminate GPR on work sites.

Sent from my SM-T350 using Tapatalk

A little known fact is that the conceptual idea we've been taught that electricity follows the path of least resistance is utterly false. It actually follows all paths proportional to their conductance which is the inverse of resistance. This becomes important when we move from a 1D system to grounding which is clearly 2D. As the ground electrode on say a pole gets further from the substation ground it would seem that resistance increases. On any given path this is true and it's basically linear but the number of paths between the two depends on the area between them so it's increasing with the square of the distance. So when we divide by the number of paths the surprising fact is that Earth resistance is proportional to the inverse of distance. Even though Earth isn't a great conductor usually about a mile away the resistance equals the neutral (which is increasing) and quickly surpasses it within a few miles to where effectively it's almost a dead short to the substation. Thus almost the entire voltage drop is over the hot and the neutral voltage drop is almost zero. You can verify this in the IEEE green book or just look at the formulas in any 3 point ground testing manual where you divide by the distance to get resistance. Within a typical structure there are tons of research papers that show that conduit resistance is far less than the neutral so once again, the neutral sees little to no voltage during a fault. It's only close to the transformer or within a substation, or close to a faulted transmission tower that ground potential rise or GPR actually becomes a serious safety hazard. Even then the danger isn't the fact that say the tower or the Earth is energized. It's the gradient or difference through the ground so foot to foot is the hazard. That's why they teach linemen to keep their feet together and shuffle or bunny hop if they are caught near a downed line and need to escape. So going back to the OP, there is little or no neutral voltage. To the post about SKM output that's at the transformer, not close to the fault.

The original Edison DC distribution systems used a single hot and peg grounding as the return. There were lots of safety reports near these systems, all GPR issues.

Today we use extensive grounding under substation yards and multigrounded and bonded systems everywhere else. Because of GPR line crews are moving to using equipotential grounding as well as ground grid blankets for ground men to reduce or eliminate GPR on work sites.

Sent from my SM-T350 using Tapatalk

## Comment