Grounding Panel / Building in Separate Locations

[Keri_WW]

I've got a panelboard being served by the utility transformer, which will be a couple hundred feet away from the actual building to be served. This panelboard will feed a gutter and two or three other panels.

This is a 240V single phase system. As far as grounding goes, I am providing 4#3/0 (2 current carrying conductors, ground, and a grounded neutral) from the xfmr to the panelboard. I am then providing a #4 ground connected to a 10' ground rod. From this panelboard, I am running 3#250 and 1#4 (upsized for VD) to the gutter. At this gutter I am providing another ground rod, and calling for #4 to the metal water pipe, gas piping (if applicable), and an exothermic weld to building steel.

Does this all sound correct? My main areas of confusion are the # and sizes of ground from xfmr to first panel, grounding required at first panel, and grounding required at building gutter.

Thanks for the help!!
Keri:grin::grin:

 

[augie47]

There is normally no need to have a grounding conductor from the transformer to the 1st panel. The grounded conductor serves as you means to ground (bond) the service panel.
From your first service panel to the building the 4 wire system seems correct and you bonding to building steel, water, gas et could be accomplished at the gutter as you state. All these connections would be to your equipment ground from the 1st panel with no grounded conductor connection.

 

[Keri_WW]

Thanks as always Augie. I will show 3 wires from the xfmr to panel. I'm sure I'm in the same boat with most people when I say that I've never been able to wrap my brain around grounding! I need a grounding for dummies book! hah

Keri

 

[augie47]

we all do :grin:

 

[John120/240]

IAEI "SOARES Book On Grounding" is a good source.

 

[Keri_WW]

I actually have the Soares book. I must have fallen asleep getting into chapter 3 or 4 because it really seemed no better at explaining things than the NEC!

Keri