Instructor Question on Zero Ohms Ground Point

[tom baker]

I received a question on the following:
"For a ground rod with 10 ohms to ground. If the zero ohm point is considered to be the neutral conductor then the current path is from the ungrounded conductor through the 10 ohms to earth, then up through the 25 ohm to neutral as they are bonded in main panel. The total resistance is then 35 ohms as they are considered to be in series. The current is then 3.43 amps. If earth is considered to be the zero ohm point then the 10 ohm and the 25 ohm ground are in parallel. This makes the unknown ground rod have a 16.67 ohms on it's own. The ungrounded conductor would then draw 7.2 amps. It looks like I need to know where zero ohms is located. I want to use this in class when I,m trying to explain grounding but need more clarification. Thanks again for your help."

 

[cs409]

Re: Instructor Question on Zero Ohms Ground Point

that is an interesting question...but do you think earth could ever be 0? something else, if your counting earth and the rod, i think you should go ahead and add the wire which connects after all you did mention the panel!..... this is a class room what if situation right? but to get 0 neutral u will need 2 equal loads on one ground(aka neutral now, multi wire, and or service 240v etc)

[ June 19, 2004, 03:17 PM: Message edited by: cs409 ]

 

[bphgravity]

Re: Instructor Question on Zero Ohms Ground Point

I'm confused. Is this question in regard to a ground resistance test or a theoretical fault calculation.