Gounding a detached structure

[pv Installs]

Recently we installed a solar system to a detached barn. This barn has no electricity ran to it. We ran the solar lines off the roof through a trench to the house. Inspector failed us because he said the barn now has feeders and needs to be grounded with 2 ground rods.. what are we supposed to tie the ground into? I'm assuming the disconnect for the solar system? But then wouldn't that make a parallel ground?

 

[wwhitney]

Recently we installed a solar system to a detached barn. This barn has no electricity ran to it. We ran the solar lines off the roof through a trench to the house. Inspector failed us because he said the barn now has feeders and needs to be grounded with 2 ground rods.. what are we supposed to tie the ground into?

The EGC at the disconnect on the barn. That would be an AC disconnect if the inverter is on the barn, or a DC disconnect if the inverter is elsewhere.

See 690.47(A), which in the 2017 NEC starts off "A building or structure supporting a PV array shall have a grounding electrode system installed in accordance with Part III of Article 250."

Cheers, Wayne

 

[pv Installs]

The EGC at the barn disconnect.

See 690.47(A), which in the 2017 NEC starts off "A building or structure supporting a PV array shall have a grounding electrode system installed in accordance with Part III of Article 250."

Cheers, Wayne

That dosent answer the question. Where do attach the ground if the structure has no electricity?

 

[pv Installs]

The EGC at the disconnect on the barn. That would be an AC disconnect if the inverter is on the barn, or a DC disconnect if the inverter is elsewhere.

See 690.47(A), which in the 2017 NEC starts off "A building or structure supporting a PV array shall have a grounding electrode system installed in accordance with Part III of Article 250."

Cheers, Wayne

It's a microinver system. Running a ground to the AC disconnect at the barn would create a parallel ground wouldn't it?

 

[winnie]

And yes, this _will_ create parallel paths between the EGC system and soil. In general, this is _not_ a problem.

The issue you are thinking of (which is a problem) is multiple bonds between neutral and soil or neutral and the EGC system. This will inject neutral current into the EGC system or the soil.

Just confirming: you do have a separate EGC and neutral in the feeder to the barn, or you have a 240V feeder with EGC but no neutral, correct? You tie the _EGC_ to the detached structure grounding electrodes.

-Jonathan

 

[LarryFine]

Welcome to the forum.

.. what are we supposed to tie the ground into? I'm assuming the disconnect for the solar system? But then wouldn't that make a parallel ground?

The rods would connect to the grounding conductor of the solar equipment.

You would not connect a neutral to the grounding conductor in the shed.

Earth is not conductive enough to be considered to be a parallel pathway.

 

[wwhitney]

That dosent answer the question. Where do attach the ground if the structure has no electricity?

The structure will have electricity once the panels and microinverters are installed. The AC feeder from/to the panel will be energized by the grid at all times. So the barn will require a 225.31 disconnect. Tie the barn GES to the feeder EGC in the 225.31 disconnect.

Cheers, Wayne

 

[jaggedben]

I agree with Wayne on all points. But if by chance you are getting away with not having a disconnect, you could also connect the rods directly to the solar array, or to the EGC at a junction box.

 

[electrofelon]

Seems kinda like a strange setup. Why didn't you just put a panel in the barn? Don't you need a combiner anyway? How many inverter circuits y'got?