Fluke Article - Is this accurate?

[us3rnotfound]

I came across this Fluke article on Grounding SDSs: http://www.fluke.com/fluke/usen/com...ding/Grounding-Separately-Derived-Systems.htm

The writer of the article makes this statement:
"The neutral and ground must be connected to the transformer neutral bus. Making the N-G bond at the main panel is not advised in order to segregate normal return currents from ground currents. The transformer neutral bus is the only point on the system where the neutral and ground should be bonded."

This didn't seem right to me, I thought that the N-G bond should indeed be installed in the main panelboard.

Thanks in advance.

 

[GoldDigger]

I came across this Fluke article on Grounding SDSs: http://www.fluke.com/fluke/usen/com...ding/Grounding-Separately-Derived-Systems.htm

The writer of the article makes this statement:
"The neutral and ground must be connected to the transformer neutral bus. Making the N-G bond at the main panel is not advised in order to segregate normal return currents from ground currents. The transformer neutral bus is the only point on the system where the neutral and ground should be bonded."

This didn't seem right to me, I thought that the N-G bond should indeed be installed in the main panelboard.

Thanks in advance.

For a utility service, you have no control of anything toward POCO from the meter and panelboard, so you have to have a bond there to make sure that there is one regardless of what POCO does.
For an SDS, you control the transformer and the panel, and so putting the bond at the transformer is an option for you. Which of the two places is best can be the subject of lots of argument, and the answer will depend in part on whether you are incorporating either Ground Fault Protection or GFCI into the system.
The statement is correct that you do not generally want to do both.

 

[us3rnotfound]

So to transition what you said to an analogy so I can better understand, at my home, I'm sure the N-G bond exists inside the main and only panelboard.

However in the transformer outside where my power comes from, I have no idea as to whether an N-G bond exists or not? Is there effectively a ground loop of some sort if there's bonding at both locations, the source transformer and my house panelboard?

 

[Dennis Alwon]

So to transition what you said to an analogy so I can better understand, at my home, I'm sure the N-G bond exists inside the main and only panelboard.

However in the transformer outside where my power comes from, I have no idea as to whether an N-G bond exists or not? Is there effectively a ground loop of some sort if there's bonding at both locations, the source transformer and my house panelboard?

The utility transformer at your home does not have an equipment grounding conductor running to it. You have 3 wires- 2 hots and a grounded conductor (Neutral). The neutral is bonded to the case at your home along with any equipment grounding conductor's that exist in the main panel from branch circuits or feeders.

 

[Dennis Alwon]

Check out this article from EC&M

 

[don_resqcapt19]

I came across this Fluke article on Grounding SDSs: http://www.fluke.com/fluke/usen/com...ding/Grounding-Separately-Derived-Systems.htm

The writer of the article makes this statement:
"The neutral and ground must be connected to the transformer neutral bus. Making the N-G bond at the main panel is not advised in order to segregate normal return currents from ground currents. The transformer neutral bus is the only point on the system where the neutral and ground should be bonded."

This didn't seem right to me, I thought that the N-G bond should indeed be installed in the main panelboard.

Thanks in advance.

It is not correct as the NEC permits the bond to be made at any point from the secondary of the transformer to the OCPD. There is no electrical difference between the bonding at one point or another. If the system is installed per the NEC rules the "normal return currents and the ground currents" will be segregated. No matter where the bond is installed, there will be a supply side bonding jumper between the transformer and the OCPD. It will be connected to the grounded conductor at the same point where the GEC is connected to the grounded conductor.

That being said there are a number of things in the article that are not very clear. The way he starts the article, it appears that he is taking about utility transformers, but then he changes to SDS.