Help demystify the Code - separately derived systems

[ggunn]

Is a grid tied PV system a separately derived system or not? One article in the NEC2008 says it is with no disclaimer. Another says that it "may be" provided it has no direct electrical connection to another source. What is a direct connection? Is a connection through a breaker considered direct? And then there's the language about having "no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system".

The output of a grid tied PV system is by definition connected to the grid. The grounds are connected as well. Does that mean it cannot be considered to be separately derived?

 

[don_resqcapt19]

I don't see how the output of an inverter that is tied to the utility system can ever be SDS.

 

[G._S._Ohm]

Try this
http://www.google.com/search?hl=en&...q="separately+derived"+electrical&btnG=Search
and
http://www.google.com/search?hl=en&...ne+"direct+electrical+connection"&btnG=Search
and I guess the majority rules.

If equally credible sources contradict each other, then you definitely have a problem.

 

[raider1]

I don't see how the output of an inverter that is tied to the utility system can ever be SDS.

I agree.

Chris

 

[Open Neutral]

I don't see how the output of an inverter that is tied to the utility system can ever be SDS.

FWIW: A SMA grid-tie system I am working on will also tag-along with SMA battery inverters {Sunny Island}...