Wind Turbine grounding

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wirebender said:
Does the 2008 require a ground rod for the pole of a wind turbine?

It's bolted on a 6'x'6x3'deep concrete mat with 1 1/4" x 32" bolts.


It is a Skystream 3.7.
Click to expand...

Well, it is a seperate structure, or a structure.
 
The turbine would be likely be considered a separate derived system thus grounding of the applicable section in Article 250 would be required.
 
bphgravity said:
The turbine would be likely be considered a separate derived system thus grounding of the applicable section in Article 250 would be required.
Click to expand...

I should have posted this:


windturbine.png



Note the area I highlighted in green says "optional". Elsewhere it says "if required by local codes.

I highlighted the neutral connection in yellow. Since the neutrals are connected (unswitched) it wouldn't be separately derived would it?


Required or not would a ground rod even do any good? Wouldn't the bolts in the concrete mat have considerably less resistance?
 
Yes, you are correct. Grounding at the tower itself would be optional for protection from lightning exclusively.

It doesn't appear this system interconnects with the utility service. Will the back-fed breaker at the service panel be interlocked with the main?
 
Well your diagram does not show an anti-islanding provisions so I imagine bph is concerned about back feeding the grid.

It is my guess this is in fact a grid tied system and there are anti islanding controls somewhere in the system.
 
iwire said:
Well your diagram does not show an anti-islanding provisions so I imagine bph is concerned about back feeding the grid.

It is my guess this is in fact a grid tied system and there are anti islanding controls somewhere in the system.
Click to expand...


That's kinda what I thought Bryan was asking but I wasn't sure.

This is grid tied through the 20A breaker. Loss of utility power causes the blades of the windmill to be locked.
 
From the manual:

In addition to adjusting its operation in response to wind conditions Skystream also monitors the electrical utility grid and its own internal
health. Should the electric utility voltage or frequency differ from Skystream?s voltage, for example due to a power failure, Skystream
will disconnect from the grid and enter a ?braked mode?. While in this mode the blades are held stationary while the Skystream monitors
the utility power. If Skystream determines that the power has returned to within specification, it will re-connect to the grid and
resume normal operation.
Click to expand...
 
Got to see the install of four skystream 3.7's today. Never seen one before today. Install is simple. Not sure what all is happening inside the turbine enclosure.
 
Also noticed the installer used NM cable in buried PVC. You can see the orange 10-3 in the pics. I'm not much of a resi-guy and don't work with NM all that much but I thought buried, even in conduit was a wet location and NM was a no-no - correct?

I also asked the installer how he converted from 1" at the turbines to the 2 1/2" I saw back at the meter location. He said he buried junction boxes. None were visible or marked. Hmmmm - violation of 314.29?
 
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Thanks wirebender. That helps my understanding a bunch.

The owner on the install I saw today was installing a new service with only the 4 turbines backfeeding it. No other load. His home is well back off the road (1000'?) so he is putting the first turbine only roughly 100' from the road, installing a service near it and using this service only as a credit to his home useage in some deal he worked out with the power company.

I mentioned the NM cable to him and he seemed unconcerned. I did not inquiry as to whether he was getting the installation inspected or not. If so I have to think he will be gigged on it.

Thanks again.

bbaumer
 
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