Supply side Interconnections

[Smart $]

An isolation transformer doesn't change anything. We are talking interconnected systems. Any grid-tied power source cannot be an SDS. It can be connected to an SDS, but it cannot by itself be an SDS.

 

[c_picard]

An isolation transformer doesn't change anything. We are talking interconnected systems. Any grid-tied power source cannot be an SDS. It can be connected to an SDS, but it cannot by itself be an SDS.

+1

 

[jaggedben]

On a strict reading of code definitions, I agree with shortcircuit.

However, I believe that with respect to system grounding, the point is moot. 690.47 supersedes 250.

 

[Smart $]

On a strict reading of code definitions, I agree with shortcircuit.

If any load can draw its power from both the service and the PV system concurrently, the PV system cannot be SDS.

However, I believe that with respect to system grounding, the point is moot. 690.47 supersedes 250.

Not entirely...

But what's relevant for line-side connections is whether you want to call the transition disconnect a service disconnect or a PV system disconnect. There are differences in grounding requirements. If you apply the requirements of 690.47 that supersede Article 250, you cannot call it a service disconnect... JMO

 

[GoldDigger]

If any load can draw its power from both the service and the PV system concurrently, the PV system cannot be SDS....

A very good practical rule, even if it may be hard to derive that from the definitions.


Tapatalk!

 

[Smart $]

A very good practical rule, even if it may be hard to derive that from the definitions.

But technically I should have said current instead of power.

 

[jaggedben]

If any load can draw its power from both the service and the PV system concurrently, the PV system cannot be SDS.

How about the DC PV conductors? What system do they belong to, and do they have direct connection to the rest of the premises wiring?

I agree that SDS rules shouldn't apply to PV systems, but it might take some new language in the code to get everyone else to agree.

 

[jaggedben]

Not entirely...

But what's relevant for line-side connections is whether you want to call the transition disconnect a service disconnect or a PV system disconnect. There are differences in grounding requirements.

The point was that none of the rules that 250 brings up with regard to an SDS apply to a PV system, even if a PV system meets the NEC definition of an SDS. That's because 690.47 tells you how to do system grounding for a PV system, and refers to the relevant sections of 250 as necessary.

If you apply the requirements of 690.47 that supersede Article 250, you cannot call it a service disconnect... JMO

That sentence makes no sense to me. Nothing in 690.47 contradicts the requirements for service disconnecting means in 230 or 250.

 

[Smart $]

How about the DC PV conductors? What system do they belong to, and do they have direct connection to the rest of the premises wiring?

...

Anything on the PV side of the PV system [AC] disconnect is part of the PV system... :roll:

If you have a hybrid PV system, it would be an SDS with respect to the loads that only the PV system power.